To see the other types of publications on this topic, follow the link: Clathrin-dependent endocytosis.
Journal articles on the topic 'Clathrin-dependent endocytosis'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Clathrin-dependent endocytosis.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
MOUSAVI, Seyed Ali, Lene MALERØD, Trond BERG, and Rune KJEKEN. "Clathrin-dependent endocytosis." Biochemical Journal 377, no. 1 (2004): 1–16. http://dx.doi.org/10.1042/bj20031000.
Full textAbstract:
The process by which clathrin-coated vesicles are produced involves interactions of multifunctional adaptor proteins with the plasma membrane, as well as with clathrin and several accessory proteins and phosphoinositides. Here we review recent findings highlighting new insights into mechanisms underlying clathrin-dependent endocytosis.
2
Torgersen, Maria L., Grethe Skretting, Bo van Deurs, and Kirsten Sandvig. "Internalization of cholera toxin by different endocytic mechanisms." Journal of Cell Science 114, no. 20 (2001): 3737–47. http://dx.doi.org/10.1242/jcs.114.20.3737.
Full textAbstract:
The mechanism of cholera toxin (CT) internalization has been investigated using Caco-2 cells transfected with caveolin to induce formation of caveolae, HeLa cells with inducible synthesis of mutant dynamin (K44A) and BHK cells in which antisense mRNA to clathrin heavy chain can be induced. Here we show that endocytosis and the ability of CT to increase the level of cAMP were unaltered in caveolin-transfected cells grown either in a non-polarized or polarized manner. Treatment of Caco-2 cells with filipin reduced CT-uptake by less than 20%, suggesting that caveolae do not play a major role in the uptake. Extraction of cholesterol by methyl-β-cyclodextrin, which removes caveolae and inhibits uptake from clathrin-coated pits, gave 30-40% reduction of CT-endocytosis. Also, CT-uptake in HeLa K44A cells was reduced by 50-70% after induction of mutant dynamin, which inhibits both caveolae- and clathrin-dependent endocytosis. These cells contain few caveolae, and nystatin and filipin had no effect on CT-uptake, indicating major involvement of clathrin-coated pits in CT-internalization. Similarly, in BHK cells, where clathrin-dependent endocytosis is blocked by induction of antisense clathrin heavy chain, the CT-uptake was reduced by 50% in induced cells. In conclusion, a large fraction of CT can be endocytosed by clathrin-dependent as well as by caveolae- and clathrin-independent endocytosis in different cell types.
3
Stirling, Lee, Michael R. Williams, and Anthony D. Morielli. "Dual Roles for RHOA/RHO-Kinase In the Regulated Trafficking of a Voltage-sensitive Potassium Channel." Molecular Biology of the Cell 20, no. 12 (2009): 2991–3002. http://dx.doi.org/10.1091/mbc.e08-10-1074.
Full textAbstract:
Kv1.2 is a member of the Shaker family of voltage-sensitive potassium channels and contributes to regulation of membrane excitability. The electrophysiological activity of Kv1.2 undergoes tyrosine kinase-dependent suppression in a process involving RhoA. We report that RhoA elicits suppression of Kv1.2 ionic current by modulating channel endocytosis. This occurs through two distinct pathways, one clathrin-dependent and the other cholesterol-dependent. Activation of Rho kinase (ROCK) via the lysophosphatidic acid (LPA) receptor elicits clathrin-dependent Kv1.2 endocytosis and consequent attenuation of its ionic current. LPA-induced channel endocytosis is blocked by the ROCK inhibitor Y27632 or by clathrin RNA interference. In contrast, steady-state endocytosis of Kv1.2 in unstimulated cells is cholesterol dependent. Inhibition of basal ROCK signaling with Y27632 increased surface Kv1.2, an effect that persists in the presence of clathrin small interfering RNA and that is not additive to the increase in surface channel levels elicited by the cholesterol sequestering drug filipin. Temperature block experiments show that ROCK affects cholesterol-dependent trafficking by modulating the recycling of endocytosed channel back to the plasma membrane. Both receptor-stimulated and steady-state Kv1.2 trafficking modulated by RhoA/ROCK required the activation of dynamin as well as the ROCK effector Lim-kinase, indicating a key role for actin remodeling in RhoA-dependent Kv1.2 regulation.
4
Ezratty, Ellen J., Claire Bertaux, Eugene E. Marcantonio, and Gregg G. Gundersen. "Clathrin mediates integrin endocytosis for focal adhesion disassembly in migrating cells." Journal of Cell Biology 187, no. 5 (2009): 733–47. http://dx.doi.org/10.1083/jcb.200904054.
Full textAbstract:
Focal adhesion disassembly is regulated by microtubules (MTs) through an unknown mechanism that involves dynamin. To test whether endocytosis may be involved, we interfered with the function of clathrin or its adaptors autosomal recessive hypercholesteremia (ARH) and Dab2 (Disabled-2) and found that both treatments prevented MT-induced focal adhesion disassembly. Surface labeling experiments showed that integrin was endocytosed in an extracellular matrix–, clathrin-, and ARH- and Dab2-dependent manner before entering Rab5 endosomes. Clathrin colocalized with a subset of focal adhesions in an ARH- and Dab2-dependent fashion. Direct imaging showed that clathrin rapidly accumulated on focal adhesions during MT-stimulated disassembly and departed from focal adhesions with integrin upon their disassembly. In migrating cells, depletion of clathrin or Dab2 and ARH inhibited focal adhesion disassembly and decreased the rate of migration. These results show that focal adhesion disassembly occurs through a targeted mechanism involving MTs, clathrin, and specific clathrin adaptors and that direct endocytosis of integrins from focal adhesions mediates their disassembly in migrating cells.
5
Peng, Tao, Jia-Li Wang, Wei Chen, et al. "Entry of dengue virus serotype 2 into ECV304 cells depends on clathrin-dependent endocytosis, but not on caveolae-dependent endocytosis." Canadian Journal of Microbiology 55, no. 2 (2009): 139–45. http://dx.doi.org/10.1139/w08-107.
Full textAbstract:
Caveolae- and clathrin-mediated endocytosis are major internalization pathways used by several pathogens; however, their distinctive roles in dengue virus (DV) entry have not been addressed. In this study, we compared the involvement of caveolae- and clathrin-mediated endocytosis in the infectious entry of DV serotype 2 (DV2) into human endothelial-like ECV304 cells. Confocal microscopy study on DV2-infected cells showed that viral antigens were co-localized with clathrin heavy chains, epidermal growth factor pathway substrate clone 15 (Eps15), and adaptin-α, but not with caveolin-1. Treatment with chlorpromazine, which inhibits clathrin-dependent endocytosis, led to reduced virus entry into cells, whereas treatment with nystatin, a caveolae inhibitory agent, did not. Furthermore, gene silencing of Eps15 resulted in an average of 75% reduced infection of ECV304 cells by DV2. Our results demonstrated that DV2 enters ECV304 cells by clathrin-dependent endocytosis, not by caveolae-dependent endocytosis.
6
Batchelder, Erika M., and Defne Yarar. "Differential Requirements for Clathrin-dependent Endocytosis at Sites of Cell–Substrate Adhesion." Molecular Biology of the Cell 21, no. 17 (2010): 3070–79. http://dx.doi.org/10.1091/mbc.e09-12-1044.
Full textAbstract:
Clathrin-dependent endocytosis is a major route for the cellular import of macromolecules and occurs at the interface between the cell and its surroundings. However, little is known about the influences of cell–substrate attachment in clathrin-coated vesicle formation. Using biochemical and imaging-based methods, we find that cell–substrate adhesion reduces the rate of endocytosis. Clathrin-coated pits (CCPs) in proximity to substrate contacts exhibit slower dynamics in comparison to CCPs found more distant from adhesions. Direct manipulation of the extracellular matrix (ECM) to modulate adhesion demonstrates that tight adhesion dramatically reduces clathrin-dependent endocytosis and extends the lifetimes of clathrin structures. This reduction is in part mediated by integrin-matrix engagement. In addition, we demonstrate that actin cytoskeletal dynamics are differentially required for efficient endocytosis, with a stronger requirement for actin polymerization in areas of adhesion. Together, these results reveal that cell–substrate adhesion regulates clathrin-dependent endocytosis and suggests that actin assembly facilitates vesicle formation at sites of adhesion.
7
Hansen, S. H., K. Sandvig, and B. van Deurs. "Molecules internalized by clathrin-independent endocytosis are delivered to endosomes containing transferrin receptors." Journal of Cell Biology 123, no. 1 (1993): 89–97. http://dx.doi.org/10.1083/jcb.123.1.89.
Full textAbstract:
We have previously demonstrated that the preendosomal compartment in addition to clathrin-coated vesicles, comprises distinct nonclathrin coated endocytic vesicles mediating clathrin-independent endocytosis (Hansen, S. H., K. Sandvig, and B. van Deurs. 1991. J. Cell Biol. 113:731-741). Using K+ depletion in HEp-2 cells to block clathrin-dependent but not clathrin-independent endocytosis, we have now traced the intracellular routing of these nonclathrin coated vesicles to see whether molecules internalized by clathrin-independent endocytosis are delivered to a unique compartment or whether they reach the same early and late endosomes as encountered by molecules internalized with high efficiency through clathrin-coated pits and vesicles. We find that Con A-gold internalized by clathrin-independent endocytosis is delivered to endosomes containing transferrin receptors. After incubation of K(+)-depleted cells with Con A-gold for 15 min, approximately 75% of Con A-gold in endosomes is colocalized with transferrin receptors. Endosomes containing only Con A-gold may be accounted for either by depletion of existing endosomes for transferrin receptors or by de novo generation of endosomes. Cationized gold and BSA-gold internalized in K(+)-depleted cells are also delivered to endosomes containing transferrin receptors. h-lamp-1-enriched compartments are only reached occasionally within 30 min in K(+)-depleted as well as in control cells. Thus, preendosomal vesicles generated by clathrin-independent endocytosis do not fuse to any marked degree with late endocytic compartments. These data show that in HEp-2 cells, molecules endocytosed without clathrin are delivered to the same endosomes as reached by transferrin receptors internalized through clathrin-coated pits.
8
Delos Santos, Ralph Christian, Stephen Bautista, Stefanie Lucarelli, et al. "Selective regulation of clathrin-mediated epidermal growth factor receptor signaling and endocytosis by phospholipase C and calcium." Molecular Biology of the Cell 28, no. 21 (2017): 2802–18. http://dx.doi.org/10.1091/mbc.e16-12-0871.
Full textAbstract:
Clathrin-mediated endocytosis is a major regulator of cell-surface protein internalization. Clathrin and other proteins assemble into small invaginating structures at the plasma membrane termed clathrin-coated pits (CCPs) that mediate vesicle formation. In addition, epidermal growth factor receptor (EGFR) signaling is regulated by its accumulation within CCPs. Given the diversity of proteins regulated by clathrin-mediated endocytosis, how this process may distinctly regulate specific receptors is a key question. We examined the selective regulation of clathrin-dependent EGFR signaling and endocytosis. We find that perturbations of phospholipase Cγ1 (PLCγ1), Ca2+, or protein kinase C (PKC) impair clathrin-mediated endocytosis of EGFR, the formation of CCPs harboring EGFR, and EGFR signaling. Each of these manipulations was without effect on the clathrin-mediated endocytosis of transferrin receptor (TfR). EGFR and TfR were recruited to largely distinct clathrin structures. In addition to control of initiation and assembly of CCPs, EGF stimulation also elicited a Ca2+- and PKC-dependent reduction in synaptojanin1 recruitment to clathrin structures, indicating broad control of CCP assembly by Ca2+ signals. Hence EGFR elicits PLCγ1-calcium signals to facilitate formation of a subset of CCPs, thus modulating its own signaling and endocytosis. This provides evidence for the versatility of CCPs to control diverse cellular processes.
9
Sauvonnet, Nathalie, Annick Dujeancourt та Alice Dautry-Varsat. "Cortactin and dynamin are required for the clathrin-independent endocytosis of γc cytokine receptor". Journal of Cell Biology 168, № 1 (2004): 155–63. http://dx.doi.org/10.1083/jcb.200406174.
Full textAbstract:
Endocytosis is critical for many cellular functions. We show that endocytosis of the common γc cytokine receptor is clathrin independent by using a dominant-negative mutant of Eps15 or RNA interference to knock down clathrin heavy chain. This pathway is synaptojanin independent and requires the GTPase dynamin. In addition, this process requires actin polymerization. To further characterize the function of dynamin in clathrin-independent endocytosis, in particular its connection with the actin cytoskeleton, we focused on dynamin-binding proteins that interact with F-actin. We compared the involvement of these proteins in the clathrin-dependent and -independent pathways. Thus, we observed that intersectin, syndapin, and mAbp1, which are necessary for the uptake of transferrin (Tf), a marker of the clathrin route, are not required for γc receptor endocytosis. Strikingly, cortactin is needed for both γc and Tf internalizations. These results reveal the ubiquitous action of cortactin in internalization processes and suggest its role as a linker between actin dynamics and clathrin-dependent and -independent endocytosis.
10
Tuli, Amit, Mahak Sharma, Haley Capek, Naava Naslavsky, Steve Caplan, and Joyce Solheim. "APLP2 Diverts MHC-Peptide Complexes to Clathrin-Mediated Endocytosis and Lysosomal Degradation (78.14)." Journal of Immunology 182, no. 1_Supplement (2009): 78.14. http://dx.doi.org/10.4049/jimmunol.182.supp.78.14.
Full textAbstract:
Abstract The amyloid precursor-like protein 2 (APLP2) is a secreted protein that is ubiquitously expressed. We have shown previously that APLP2 associates with peptide-bound forms of H-2Kd, and influences the endocytosis, surface expression, stability, and turnover of Kd. Our new findings indicate that APLP2 is internalized in a clathrin-dependent manner, as a dominant negative dynamin II mutant and the C-terminal tail of AP180 (both inhibitors of clathrin-dependent endocytosis) block its internalization. However, endocytosis of Kd is not blocked by these inhibitors, consistent with findings by others that MHC class I molecules are internalized mainly through a clathrin-independent pathway. Furthermore, the APLP2 cytoplasmic tail contains overlapping tyrosine-based motifs that can potentially bind to adaptor protein AP-2. Mutation of the tyrosine in this sequence severely impaired endocytosis of APLP2. This APLP2 mutant, unlike wild-type APLP2, failed to enhance the endocytosis of Kd molecules. Also, we found that APLP2 and Kd bind at the plasma membrane (PM) and are internalized together. Upon increased APLP2 expression, Kd molecules were predominantly directed to the lysosomes rather than recycled to the PM. These findings suggest a model in which APLP2 binds Kd at the PM, facilitates uptake of Kd in a clathrin-dependent manner, and routes the endocytosed Kd to the lysosomal degradation pathway. Thus, APLP2 has a multi-step trafficking function which influences the expression of MHC-peptide complexes at the PM. [NIH GM57428 & GM74876]
11
Sieczkarski, Sara B., and Gary R. Whittaker. "Influenza Virus Can Enter and Infect Cells in the Absence of Clathrin-Mediated Endocytosis." Journal of Virology 76, no. 20 (2002): 10455–64. http://dx.doi.org/10.1128/jvi.76.20.10455-10464.2002.
Full textAbstract:
ABSTRACT Influenza virus has been described to enter host cells via clathrin-mediated endocytosis. However, it has also been suggested that other endocytic routes may provide additional entry pathways. Here we show that influenza virus may enter and infect HeLa cells that are unable to take up ligands by clathrin-mediated endocytosis. By overexpressing a dominant-negative form of the Eps15 protein to inhibit clathrin-mediated endocytosis, we demonstrate that while transferrin uptake and Semliki Forest virus infection were prevented, influenza virus could enter and infect cells expressing Eps15Δ95/295. This finding is supported by the successful infection of cells with influenza virus in the presence of chemical treatments that block endocytosis, namely, chlorpromazine and potassium depletion. We show also that influenza virus may infect cells incapable of uptake by caveolae. Treatment with the inhibitors nystatin, methyl-β-cyclodextrin, and genistein, as well as transfection of cells with dominant-negative caveolin-1, had no effect on influenza virus infection. By combining inhibitory methods to block both clathrin-mediated endocytosis and uptake by caveolae in the same cell, we demonstrate that influenza virus may infect cells by an additional non-clathrin-dependent, non-caveola-dependent endocytic pathway. We believe this to be the first conclusive analysis of virus entry via such a non-clathrin-dependent pathway, in addition to the traditional clathrin-dependent route.
12
Wu, Xufeng, Xiaohong Zhao, Lauren Baylor, Shivani Kaushal, Evan Eisenberg, and Lois E. Greene. "Clathrin exchange during clathrin-mediated endocytosis." Journal of Cell Biology 155, no. 2 (2001): 291–300. http://dx.doi.org/10.1083/jcb.200104085.
Full textAbstract:
During clathrin-mediated endocytosis, clathrin-coated pits invaginate to form clathrin-coated vesicles (CVs). Since clathrin-coated pits are planar structures, whereas CVs are spherical, there must be a structural rearrangement of clathrin as invagination occurs. This could occur through simple addition of clathrin triskelions to the edges of growing clathrin-coated pits with very little exchange occurring between clathrin in the pits and free clathrin in the cytosol, or it could occur through large scale exchange of free and bound clathrin. In the present study, we investigated this question by studying clathrin exchange both in vitro and in vivo. We found that in vitro clathrin in CVs and clathrin baskets do not exchange with free clathrin even in the presence of Hsc70 and ATP where partial uncoating occurs. However, surprisingly FRAP studies on clathrin-coated pits labeled with green fluorescent protein–clathrin light chains in HeLa cells show that even when endocytosis is blocked by expression of a dynamin mutant or depletion of cholesterol from the membrane, replacement of photobleached clathrin in coated pits on the membrane occurs at almost the same rate and magnitude as when endocytosis is occurring. Furthermore, very little of this replacement is due to dissolution of old pits and reformation of new ones; rather, it is caused by a rapid ATP-dependent exchange of clathrin in the pits with free clathrin in the cytosol. On the other hand, consistent with the in vitro data both potassium depletion and hypertonic sucrose, which have been reported to transform clathrin-coated pits into clathrin cages just below the surface of the plasma membrane, not only block endocytosis but also block exchange of clathrin. Taken together, these data show that ATP-dependent exchange of free and bound clathrin is a fundamental property of clathrin-coated pits, but not clathrin baskets, and may be involved in a structural rearrangement of clathrin as clathrin-coated pits invaginate.
13
Hendricks, Emily L., and Faith L. W. Liebl. "The CHD family chromatin remodeling enzyme, Kismet, promotes both clathrin-mediated and activity-dependent bulk endocytosis." PLOS ONE 19, no. 3 (2024): e0300255. http://dx.doi.org/10.1371/journal.pone.0300255.
Full textAbstract:
Chromodomain helicase DNA binding domain (CHD) proteins, including CHD7 and CHD8, remodel chromatin to enable transcriptional programs. Both proteins are important for proper neural development as heterozygous mutations in Chd7 and Chd8 are causative for CHARGE syndrome and correlated with autism spectrum disorders, respectively. Their roles in mature neurons are poorly understood despite influencing the expression of genes required for cell adhesion, neurotransmission, and synaptic plasticity. The Drosophila homolog of CHD7 and CHD8, Kismet (Kis), promotes neurotransmission, endocytosis, and larval locomotion. Endocytosis is essential in neurons for replenishing synaptic vesicles, maintaining protein localization, and preserving the size and composition of the presynaptic membrane. Several forms of endocytosis have been identified including clathrin-mediated endocytosis, which is coupled with neural activity and is the most prevalent form of synaptic endocytosis, and activity-dependent bulk endocytosis, which occurs during periods of intense stimulation. Kis modulates the expression of gene products involved in endocytosis including promoting shaggy/GSK3β expression while restricting PI3K92E. kis mutants electrophysiologically phenocopy a liquid facets mutant in response to paradigms that induce clathrin-mediated endocytosis and activity-dependent bulk endocytosis. Further, kis mutants do not show further reductions in endocytosis when activity-dependent bulk endocytosis or clathrin-mediated endocytosis are pharmacologically inhibited. We find that Kis is important in postsynaptic muscle for proper endocytosis but the ATPase domain of Kis is dispensable for endocytosis. Collectively, our data indicate that Kis promotes both clathrin-mediated endocytosis and activity-dependent bulk endocytosis possibly by promoting transcription of several endocytic genes and maintaining the size of the synaptic vesicle pool.
14
Laniosz, Valerie, Kirsten A. Holthusen, and Patricio I. Meneses. "Bovine Papillomavirus Type 1: from Clathrin to Caveolin." Journal of Virology 82, no. 13 (2008): 6288–98. http://dx.doi.org/10.1128/jvi.00569-08.
Full textAbstract:
ABSTRACT Viruses may infect cells through clathrin-dependent, caveolin-dependent, or clathrin- and caveolin-independent endocytosis. Bovine papillomavirus type 1 (BPV1) entry into cells has been shown to occur by clathrin-dependent endocytosis, a pathway that involves the formation of clathrin-coated pits and fusion to early endosomes. Recently, it has been demonstrated that the closely related JC virus can enter cells in clathrin-coated vesicles and subsequently traffic to caveolae, the organelle where vesicles of the caveolin-dependent pathway deliver their cargo. In this study, we use immunofluorescence staining of BPV1 pseudovirions to show that BPV1 overlaps with the endosome marker EEA1 early during infection and later colocalizes with caveolin-1. We provide evidence through the colocalization of BPV1 with transferrin and cholera toxin B that BPVl trafficking may not be restricted to the clathrin-dependent pathway. Disrupting the entry of caveolar vesicles did not affect BPV1 infection; however, we show that blocking the caveolar pathway postentry results in a loss of BPV1 infection. These data indicate that BPV1 may enter by clathrin-mediated endocytosis and then utilize the caveolar pathway for infection, a pattern of trafficking that may explain the slow kinetics of BPV1 infection.
15
Tanabe, Kenji, Tetsuo Torii, Waka Natsume, Sten Braesch-Andersen, Toshio Watanabe, and Masanobu Satake. "A Novel GTPase-activating Protein for ARF6 Directly Interacts with Clathrin and Regulates Clathrin-dependent Endocytosis." Molecular Biology of the Cell 16, no. 4 (2005): 1617–28. http://dx.doi.org/10.1091/mbc.e04-08-0683.
Full textAbstract:
ADP-ribosylation factor 6 (Arf6) is a small-GTPase that regulates the membrane trafficking between the plasma membrane and endosome. It is also involved in the reorganization of the actin cytoskeleton. GTPase-activating protein (GAP) is a critical regulator of Arf function as it inactivates Arf. Here, we identified a novel species of GAP denoted as SMAP1 that preferentially acts on Arf6. Although overexpression of SMAP1 did not alter the subcellular distribution of the actin cytoskeleton, it did block the endocytosis of transferrin receptors. Knock down of endogenous SMAP1 also abolished transferrin internalization, which confirms that SMAP1 is needed for this endocytic process. SMAP1 overexpression had no effect on clathrin-independent endocytosis, however. Intriguingly, SMAP1 binds directly to the clathrin heavy chain via its clathrin-box and mutation studies revealed that its GAP domain and clathrin-box both contribute to the role SMAP1 plays in clathrin-dependent endocytosis. These observations suggest that SMAP1 may be an Arf6GAP that specifically regulates one of the multiple functions of Arf6, namely, clathrin-dependent endocytosis, and that it does so by binding directly to clathrin.
16
Glodowski, Doreen R., Carlos Chih-Hsiung Chen, Henry Schaefer, Barth D. Grant, and Christopher Rongo. "RAB-10 Regulates Glutamate Receptor Recycling in a Cholesterol-dependent Endocytosis Pathway." Molecular Biology of the Cell 18, no. 11 (2007): 4387–96. http://dx.doi.org/10.1091/mbc.e07-05-0486.
Full textAbstract:
Regulated endocytosis of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptors (AMPARs) is critical for synaptic plasticity. However, the specific combination of clathrin-dependent and -independent mechanisms that mediate AMPAR trafficking in vivo have not been fully characterized. Here, we examine the trafficking of the AMPAR subunit GLR-1 in Caenorhabditis elegans. GLR-1 is localized on synaptic membranes, where it regulates reversals of locomotion in a simple behavioral circuit. Animals lacking RAB-10, a small GTPase required for endocytic recycling of intestinal cargo, are similar in phenotype to animals lacking LIN-10, a postsynaptic density 95/disc-large/zona occludens-domain containing protein: GLR-1 accumulates in large accretions and animals display a decreased frequency of reversals. Mutations in unc-11 (AP180) or itsn-1 (Intersectin 1), which reduce clathrin-dependent endocytosis, suppress the lin-10 but not rab-10 mutant phenotype, suggesting that LIN-10 functions after clathrin-mediated endocytosis. By contrast, cholesterol depletion, which impairs lipid raft formation and clathrin-independent endocytosis, suppresses the rab-10 but not the lin-10 phenotype, suggesting that RAB-10 functions after clathrin-independent endocytosis. Animals lacking both genes display additive GLR-1 trafficking defects. We propose that RAB-10 and LIN-10 recycle AMPARs from intracellular endosomal compartments to synapses along distinct pathways, each with distinct sensitivities to cholesterol and the clathrin-mediated endocytosis machinery.
17
Hyman, Tehila, Miri Shmuel, and Yoram Altschuler. "Actin Is Required for Endocytosis at the Apical Surface of Madin-Darby Canine Kidney Cells where ARF6 and Clathrin Regulate the Actin Cytoskeleton." Molecular Biology of the Cell 17, no. 1 (2006): 427–37. http://dx.doi.org/10.1091/mbc.e05-05-0420.
Full textAbstract:
In epithelial cell lines, apical but not basolateral clathrin-mediated endocytosis has been shown to be affected by actin-disrupting drugs. Using electron and fluorescence microscopy, as well as biochemical assays, we show that the amount of actin dedicated to endocytosis is limiting at the apical surface of epithelia. In part, this contributes to the low basal rate of clathrin-dependent endocytosis observed at this epithelial surface. ARF6 in its GTP-bound state triggers the recruitment of actin from the cell cortex to the clathrin-coated pit to enable dynamin-dependent endocytosis. In addition, we show that perturbation of the apical endocytic system by expression of a clathrin heavy-chain mutant results in the collapse of microvilli. This phenotype was completely reversed by the expression of an ARF6-GTP-locked mutant. These observations indicate that concomitant to actin recruitment, the apical clathrin endocytic system is deeply involved in the morphology of the apical plasma membrane.
18
Hemalatha, Anupama, Chaitra Prabhakara, and Satyajit Mayor. "Endocytosis of Wingless via a dynamin-independent pathway is necessary for signaling in Drosophila wing discs." Proceedings of the National Academy of Sciences 113, no. 45 (2016): E6993—E7002. http://dx.doi.org/10.1073/pnas.1610565113.
Full textAbstract:
Endocytosis of ligand-receptor complexes regulates signal transduction during development. In particular, clathrin and dynamin-dependent endocytosis has been well studied in the context of patterning of the Drosophila wing disc, wherein apically secreted Wingless (Wg) encounters its receptor, DFrizzled2 (DFz2), resulting in a distinctive dorso-ventral pattern of signaling outputs. Here, we directly track the endocytosis of Wg and DFz2 in the wing disc and demonstrate that Wg is endocytosed from the apical surface devoid of DFz2 via a dynamin-independent CLIC/GEEC pathway, regulated by Arf1, Garz, and class I PI3K. Subsequently, Wg containing CLIC/GEEC endosomes fuse with DFz2-containing vesicles derived from the clathrin and dynamin-dependent endocytic pathway, which results in a low pH-dependent transfer of Wg to DFz2 within the merged and acidified endosome to initiate Wg signaling. The employment of two distinct endocytic pathways exemplifies a mechanism wherein cells in tissues leverage multiple endocytic pathways to spatially regulate signaling.
19
Subtil, A., and A. Dautry-Varsat. "Microtubule depolymerization inhibits clathrin coated-pit internalization in non-adherent cell lines while interleukin 2 endocytosis is not affected." Journal of Cell Science 110, no. 19 (1997): 2441–47. http://dx.doi.org/10.1242/jcs.110.19.2441.
Full textAbstract:
The microtubule cytoskeleton is generally not considered to be essential for the first steps of clathrin-mediated endocytosis of membrane receptors. Its role in clathrin-independent endocytosis has not been investigated. We have previously shown that the cytokine interleukin 2 (IL2) is internalized in lymphoid cells expressing its receptors when clathrin-dependent endocytosis is inhibited. Here we compare the internalization of IL2 and of transferrin, a marker of clathrin-dependent endocytosis, after microtubule disruption. In hemopoietic cell lines, which express IL2 receptors, transferrin receptor entry was inhibited by about 40%. However, in adherent cell lines, transferrin entry was unaffected by microtubule disruption, as previously reported. Unlike the case for transferrin, internalization of IL2 receptors was not affected by depolymerization of the microtubule cytoskeleton in hemopoietic cell lines. These results show that IL2 and transferrin receptors do not have the same endocytic properties and support our previous conclusion that these receptors follow different pathways of endocytosis.
20
Gerhard, Ralf, Eileen Frenzel, Sebastian Goy, and Alexandra Olling. "Cellular uptake of Clostridium difficile TcdA and truncated TcdA lacking the receptor binding domain." Journal of Medical Microbiology 62, no. 9 (2013): 1414–22. http://dx.doi.org/10.1099/jmm.0.057828-0.
Full textAbstract:
The combined repetitive oligopeptides (CROPs) of Clostridium difficile toxins A (TcdA) and B (TcdB) induce clathrin-mediated endocytosis of the toxins. Inconsistently, CROP-truncated TcdA1–1874 is also capable of entering host cells and displaying full cytotoxic properties although with less potency. Pre-incubation of cells with isolated CROPs, however, reconstitutes the reduced uptake of TcdA1–1874 to the level of the full-length toxin. We believe that TcdA exhibits an additional binding motif beyond the C-terminally located CROP domain, which might interact with cellular receptor structures that are associated with alternative internalization pathways. This study therefore evaluated endocytosis routes of CROP-dependent cellular uptake for TcdA and CROP-independent cellular uptake for TcdA1–1874. Clathrin knockdown or inhibition with chlorpromazine affected subsequent internalization of TcdA and TcdA1–1874, although only to some extent, arguing for alternative, clathrin-independent endocytosis routes. Inhibition of dynamin, a GTPase essentially involved in clathrin-mediated endocytosis as well as in various clathrin-independent uptake mechanisms, affected uptake of TcdA to the same extent as clathrin inhibition. In contrast, uptake of TcdA1–1874 was almost completely eliminated in dynamin-inhibited cells. Thus, clathrin-independent uptake of TcdA1–1874 presumably depends on dynamin. These findings demonstrate that the toxins are endocytosed via complex pathways involving clathrin and dynamin, putatively enabling them to adapt to mechanisms of various cell types. With regard to the emergence of C. difficile strains producing C-terminally truncated toxins, this study emphasizes the relevance of elucidating toxin uptake as a prerequisite for the development of toxin intervention strategies.
21
Laniosz, Valerie, Sarah A. Dabydeen, Mallory A. Havens, and Patricio I. Meneses. "Human Papillomavirus Type 16 Infection of Human Keratinocytes Requires Clathrin and Caveolin-1 and Is Brefeldin A Sensitive." Journal of Virology 83, no. 16 (2009): 8221–32. http://dx.doi.org/10.1128/jvi.00576-09.
Full textAbstract:
ABSTRACT Human papillomavirus type 16 (HPV16) has been identified as being the most common etiological agent leading to cervical cancer. Despite having a clear understanding of the role of HPV16 in oncogenesis, details of how HPV16 traffics during infection are poorly understood. HPV16 has been determined to enter via clathrin-mediated endocytosis, but the subsequent steps of HPV16 infection remain unclear. There is emerging evidence that several viruses take advantage of cross talk between routes of endocytosis. Specifically, JCV and bovine papillomavirus type 1 have been shown to enter cells by clathrin-dependent endocytosis and then require caveolin-1-mediated trafficking for infection. In this paper, we show that HPV16 is dependent on caveolin-1 after clathrin-mediated endocytosis. We provide evidence for the first time that HPV16 infection is dependent on trafficking to the endoplasmic reticulum (ER). This novel trafficking may explain the requirement for the caveolar pathway in HPV16 infection because clathrin-mediated endocytosis typically does not lead to the ER. Our data indicate that the infectious route for HPV16 following clathrin-mediated entry is caveolin-1 and COPI dependent. An understanding of the steps involved in HPV16 sorting and trafficking opens up the possibility of developing novel approaches to interfere with HPV16 infection and reduce the burden of papillomavirus diseases including cervical cancer.
22
Rojek, Jillian M., Mar Perez, and Stefan Kunz. "Cellular Entry of Lymphocytic Choriomeningitis Virus." Journal of Virology 82, no. 3 (2007): 1505–17. http://dx.doi.org/10.1128/jvi.01331-07.
Full textAbstract:
ABSTRACT In contrast to most enveloped viruses that enter the host cell via clathrin-dependent endocytosis, the Old World arenavirus lymphocytic choriomeningitis virus (LCMV) enters cells via noncoated vesicles that deliver the virus to endosomes, where pH-dependent membrane fusion occurs. Here, we investigated the initial steps of LCMV infection. We found that the attachment of LCMV to its cellular receptor α-dystroglycan occurs rapidly and is not dependent on membrane cholesterol. However, subsequent virus internalization is sensitive to cholesterol depletion, indicating the involvement of a cholesterol-dependent pathway. We provide evidence that LCMV entry involves an endocytotic pathway that is independent of clathrin and caveolin and that does not require the GTPase dynamin. In addition, neither the structural integrity nor the dynamics of the actin cytoskeleton are required for infection. These findings indicate that the prototypic Old World arenavirus LCMV uses a mechanism of entry that is different from clathrin-mediated endocytosis, which is used by the New World arenavirus Junin virus, and pathways used by other enveloped viruses.
23
Kawasaki, Takumi, Takeshi Kobayashi, Takehiko Ueyama, Yasuhito Shirai та Naoaki Saito. "Regulation of clathrin-dependent endocytosis by diacylglycerol kinase δ: importance of kinase activity and binding to AP2α". Biochemical Journal 409, № 2 (2007): 471–79. http://dx.doi.org/10.1042/bj20070755.
Full textAbstract:
DGKδ (diacylglycerol kinase δ), which phosphorylates DAG (diacylglycerol) and converts it into PA (phosphatidic acid), has an important role in signal transduction. In the present study, we have demonstrated the molecular mechanism of DGKδ-mediated regulation of clathrin-dependent endocytosis that controls the internalization, recycling and degradation of receptors. Involvement of DGKδ in the regulation of clathrin-dependent endocytosis was previously proposed following genome-wide RNAi (RNA interference) screening. Clathrin-coated pits are mainly formed by clathrin and AP-2 (adaptor protein 2) complex. These proteins assemble a polyhedral lattice at the membrane and gather several endocytic accessory proteins. As the intracellular localization of DGKδ2 overlapped with clathrin-coated pits, we predicted the possible regulation of clathrin-dependent endocytosis by DGKδ2 and its interaction with some endocytosis-regulatory proteins. DGKδ2 contained the DXF-type binding motifs, and DGKδ2 bound to AP2α, a subunit of the AP-2 complex. DGKδ2 interacted with the platform subdomain in the AP2α ear domain via F369DTFRIL and D746PF sequences in the catalytic domain of DGKδ2. For further insight into the role for DGKδ2 in clathrin-dependent endocytosis, we measured the transferrin and EGF (epidermal growth factor) uptake-expressing wild-type or mutant DGKδ2 under knockdown of endogenous DGKδ. Mutants lacking binding ability to AP2α as well as kinase-negative mutants could not compensate for the uptake of transferrin inhibited by siRNA (small interfering RNA) treatment, whereas overexpression of wild-type DGKδ2 completely recovered the transferrin uptake. These results demonstrate that binding between DGKδ2 and AP2α is involved in the transferrin internalization and that DGK activity is also necessary for the regulation of the endocytic process.
24
Cheng, Zhi-Jie, Raman Deep Singh, Deepak K. Sharma, et al. "Distinct Mechanisms of Clathrin-independent Endocytosis Have Unique Sphingolipid Requirements." Molecular Biology of the Cell 17, no. 7 (2006): 3197–210. http://dx.doi.org/10.1091/mbc.e05-12-1101.
Full textAbstract:
Sphingolipids (SLs) play important roles in membrane structure and cell function. Here, we examine the SL requirements of various endocytic mechanisms using a mutant cell line and pharmacological inhibitors to disrupt SL biosynthesis. First, we demonstrated that in Chinese hamster ovary cells we could distinguish three distinct mechanisms of clathrin-independent endocytosis (caveolar, RhoA, and Cdc42 dependent) which differed in cargo, sensitivity to pharmacological agents, and dominant negative proteins. General depletion of SLs inhibited endocytosis by each clathrin-independent mechanism, whereas clathrin-dependent uptake was unaffected. Depletion of glycosphingolipids (GSLs; a subgroup of SLs) selectively blocked caveolar endocytosis and decreased caveolin-1 and caveolae at the plasma membrane. Caveolar endocytosis and PM caveolae could be restored in GSL-depleted cells by acute addition of exogenous GSLs. Disruption of RhoA- and Cdc42-regulated endocytosis by SL depletion was shown to be related to decreased targeting of these Rho proteins to the plasma membrane and could be partially restored by exogenous sphingomyelin but not GSLs. Both the in vivo membrane targeting and in vitro binding to artificial lipid vesicles of RhoA and Cdc42 were shown to be dependent upon sphingomyelin. These results provide the first evidence that SLs are differentially required for distinct mechanisms of clathrin-independent endocytosis.
25
Xinhan, Lou, Masafumi Matsushita, Manami Numaza, Akira Taguchi, Keiji Mitsui, and Hiroshi Kanazawa. "Na+/H+ exchanger isoform 6 (NHE6/SLC9A6) is involved in clathrin-dependent endocytosis of transferrin." American Journal of Physiology-Cell Physiology 301, no. 6 (2011): C1431—C1444. http://dx.doi.org/10.1152/ajpcell.00154.2011.
Full textAbstract:
In mammalian cells, nine conserved isoforms of the Na+/H+ exchanger (NHE) are known to be important for pH regulation of the cytoplasm and organellar lumens. NHE1–5 are localized to the plasma membrane, whereas NHE6–9 are localized to distinct organelles. NHE6 is localized predominantly in endosomal compartments but is also found in the plasma membrane. To investigate the role of NHE6 in endocytosis, we established NHE6-knockdown HeLa cells and analyzed the effect of this knockdown on endocytotic events. The expression level of NHE6 in knockdown cells was decreased to ∼15% of the level seen in control cells. Uptake of transferrin was also decreased. No effect was found on the endocytosis of epidermal growth factor or on the cholera toxin B subunit. Moreover, in the NHE6-knockdown cells, transferrin uptake was found to be affected in the early stages of endocytosis. Microscopic analysis revealed that, at 2 min after the onset of endocytosis, colocalization of NHE6, clathrin, and transferrin was observed, which suggests that NHE6 was localized to endocytotic, clathrin-coated vesicles. In addition, in knockdown cells, transferrin-positive endosomes were acidified, but no effect was found on cytoplasmic pH. In cells overexpressing wild-type NHE6, increased transferrin uptake was observed, but no such increase was seen in cells overexpressing mutant NHE6 deficient in ion transport. The luminal pH in transferrin-positive endosomes was alkalized in cells overexpressing wild-type NHE6 but normal in cells overexpressing mutant NHE6. These observations suggest that NHE6 regulates clathrin-dependent endocytosis of transferrin via pH regulation.
26
Hemalatha, Anupama, and Satyajit Mayor. "Recent advances in clathrin-independent endocytosis." F1000Research 8 (January 31, 2019): 138. http://dx.doi.org/10.12688/f1000research.16549.1.
Full textAbstract:
Endocytic pathways are broadly classified into clathrin dependent and independent on the basis of the requirement for the coat protein, clathrin. The molecular pathways and mechanisms underlying the formation of clathrin-independent pathways are still being explored, and this review summarizes recent advances and emerging functional roles of these diverse pathways. In particular, this review will discuss the growing consensus on the role of BAR domain proteins and the actin machinery in different clathrin-independent pathways and its significance to the functions fulfilled by these endocytic pathways.
27
Prosser, Derek C., Theodore G. Drivas, Lymarie Maldonado-Báez, and Beverly Wendland. "Existence of a novel clathrin-independent endocytic pathway in yeast that depends on Rho1 and formin." Journal of Cell Biology 195, no. 4 (2011): 657–71. http://dx.doi.org/10.1083/jcb.201104045.
Full textAbstract:
Yeast is a powerful model organism for dissecting the temporal stages and choreography of the complex protein machinery during endocytosis. The only known mechanism for endocytosis in yeast is clathrin-mediated endocytosis, even though clathrin-independent endocytic pathways have been described in other eukaryotes. Here, we provide evidence for a clathrin-independent endocytic pathway in yeast. In cells lacking the clathrin-binding adaptor proteins Ent1, Ent2, Yap1801, and Yap1802, we identify a second endocytic pathway that depends on the GTPase Rho1, the downstream formin Bni1, and the Bni1 cofactors Bud6 and Spa2. This second pathway does not require components of the better-studied endocytic pathway, including clathrin and Arp2/3 complex activators. Thus, our results reveal the existence of a second pathway for endocytosis in yeast, which suggests similarities with the RhoA-dependent endocytic pathways of mammalian cells.
28
Lundmark, Richard, and Sven R. Carlsson. "Driving membrane curvature in clathrin-dependent and clathrin-independent endocytosis." Seminars in Cell & Developmental Biology 21, no. 4 (2010): 363–70. http://dx.doi.org/10.1016/j.semcdb.2009.11.014.
Full text
29
Moskowitz, Howard S., Charles T. Yokoyama, and Timothy A. Ryan. "Highly Cooperative Control of Endocytosis by Clathrin." Molecular Biology of the Cell 16, no. 4 (2005): 1769–76. http://dx.doi.org/10.1091/mbc.e04-08-0739.
Full textAbstract:
Clathrin assembles into a dynamic two-dimensional lattice on the plasma membrane where it plays a critical role in endocytosis. To probe the regulation of this process, we used siRNA against clathrin, in combination with single cell assays for transferrin uptake as well as total internal reflection microscopy, to examine how endocytic rates and membrane dynamics depend upon cellular clathrin concentration ([Clathrin]). We find that endocytosis is tightly controlled by [Clathrin] over a very narrow dynamic range such that small changes in [Clathrin] can lead to large changes in endocytic rates, indicative of a highly cooperative process (apparent Hill coefficient, n > 6). The number of clathrin assemblies at the cell surface was invariant over a wide range of [Clathrin]; however, both the amount of clathrin in each assembly and the subsequent membrane dynamics were steeply dependent on [Clathrin]. Thus clathrin controls the structural dynamics of membrane internalization via a strongly cooperative process. We used this analysis to show that one important regulator of endocytosis, the actin cytoskeleton, acts noncompetitively as a modulator of clathrin function.
30
Qin, Siying, Xueying Wang, Pan Han, et al. "LRP1-Mediated Endocytosis May Be the Main Reason for the Difference in Cytotoxicity of Curcin and Curcin C on U2OS Osteosarcoma Cells." Toxins 14, no. 11 (2022): 771. http://dx.doi.org/10.3390/toxins14110771.
Full textAbstract:
Curcin and Curcin C, both of the ribosome-inactivating proteins of Jatropha curcas, have apparent inhibitory effects on the proliferation of osteosarcoma cell line U20S. However, the inhibitory effect of the latter is 13-fold higher than that of Curcin. The mechanism responsible for the difference has not been studied. This work aimed to understand and verify whether there are differences in entry efficiency and pathway between them using specific endocytosis inhibitors, gene silencing, and labeling techniques such as fluorescein isothiocyanate (FITC) labeling. The study found that the internalization efficiency of Curcin C was twice that of Curcin for U2OS cells. More than one entering pathway was adopted by both of them. Curcin C can enter U2OS cells through clathrin-dependent endocytosis and macropinocytosis, but clathrin-dependent endocytosis was not an option for Curcin. The low-density lipoprotein receptor-related protein 1 (LRP1) was found to mediate clathrin-dependent endocytosis of Curcin C. After LRP1 silencing, there was no significant difference in the 50% inhibitory concentration (IC50) and endocytosis efficiency between Curcin and Curcin C on U2OS cells. These results indicate that LRP1-mediated endocytosis is specific to Curcin C, thus leading to higher U2OS endocytosis efficiency and cytotoxicity than Curcin.
31
Martín-Acebes, Miguel A., Mónica González-Magaldi, Angela Vázquez-Calvo, Rosario Armas-Portela, and Francisco Sobrino. "Internalization of Swine Vesicular Disease Virus into Cultured Cells: a Comparative Study with Foot-and-Mouth Disease Virus." Journal of Virology 83, no. 9 (2009): 4216–26. http://dx.doi.org/10.1128/jvi.02436-08.
Full textAbstract:
ABSTRACT We performed a comparative analysis of the internalization mechanisms used by three viruses causing important vesicular diseases in animals. Swine vesicular disease virus (SVDV) internalization was inhibited by treatments that affected clathrin-mediated endocytosis and required traffic through an endosomal compartment. SVDV particles were found in clathrin-coated pits by electron microscopy and colocalized with markers of early endosomes by confocal microscopy. SVDV infectivity was significantly inhibited by drugs that raised endosomal pH. When compared to foot-and-mouth disease virus (FMDV), which uses clathrin-mediated endocytosis, the early step of SVDV was dependent on the integrity of microtubules. SVDV-productive endocytosis was more sensitive to plasma membrane cholesterol extraction than that of FMDV, and differential cell signaling requirements for virus infection were also found. Vesicular stomatitis virus, a model virus internalized by clathrin-mediated endocytosis, was included as a control of drug treatments. These results suggest that different clathrin-mediated routes are responsible for the internalization of these viruses.
32
Austin, C. D., D. A. Lawrence, A. A. Peden, et al. "Death-receptor activation halts clathrin-dependent endocytosis." Proceedings of the National Academy of Sciences 103, no. 27 (2006): 10283–88. http://dx.doi.org/10.1073/pnas.0604044103.
Full text
33
Chaineau, Mathilde, Lydia Danglot, Véronique Proux-Gillardeaux, and Thierry Galli. "Role of HRB in Clathrin-dependent Endocytosis." Journal of Biological Chemistry 283, no. 49 (2008): 34365–73. http://dx.doi.org/10.1074/jbc.m804587200.
Full text
34
Potapovich, Alla I., Tatyana O. Suhan, Tatsiana G. Shutava, and Vladimir A. Kostyuk. "Receptor-mediated endocytosis is an important way for gelatin nano-particles penetration into cells." Journal of the Belarusian State University. Biology, no. 1 (February 18, 2020): 3–10. http://dx.doi.org/10.33581/2521-1722-2020-1-3-10.
Full textAbstract:
Experimental data detailing the possibilities of using gelatin nanoparticles obtained by the two-stage desolvation method without the use of surfactants for delivering pharmacologically active substances to cultured normal and human cancer cells are presented. It was shown that clathrin-dependent endocytosis is the main route of entry of such nanoparticles into normal human fibroblasts and cancer cells of the MDA-MB-231 line. Due to this type of endocytosis, more than 50 % of gelatin nanoparticles enter the cells. It was shown that in the process of clathrin-dependent endocytosis, gelatin nanoparticles specifically bind to collagen receptors.
35
Long, Gang, Xiaoyu Pan, Richard Kormelink, and Just M. Vlak. "Functional Entry of Baculovirus into Insect and Mammalian Cells Is Dependent on Clathrin-Mediated Endocytosis." Journal of Virology 80, no. 17 (2006): 8830–33. http://dx.doi.org/10.1128/jvi.00880-06.
Full textAbstract:
ABSTRACT Entry of the budded virus form of baculoviruses into insect and mammalian cells is generally thought to occur through a low-pH-dependent endocytosis pathway, possibly through clathrin-coated pits. This insight is primarily based on (immuno)electron microscopy studies but requires biochemical support to exclude the use of other pathways. Here, we demonstrate using various inhibitors that functional entry of baculoviruses into insect and mammalian cells is primarily dependent on clathrin-mediated endocytosis. Our results further suggest that caveolae are somehow involved in baculovirus entry in mammalian cells. A caveolar endocytosis inhibitor, genistein, enhances baculovirus transduction in these cells considerably.
36
Singh, Raman Deep, Vishwajeet Puri, Jacob T. Valiyaveettil, David L. Marks, Robert Bittman, and Richard E. Pagano. "Selective Caveolin-1–dependent Endocytosis of Glycosphingolipids." Molecular Biology of the Cell 14, no. 8 (2003): 3254–65. http://dx.doi.org/10.1091/mbc.e02-12-0809.
Full textAbstract:
We studied the endocytosis of fluorescent glycosphingolipid (GSL) analogs in various cell types using pathway-specific inhibitors and colocalization studies with endocytic markers and DsRed caveolin-1 (cav-1). Based on inhibitor studies, all GSLs tested were internalized predominantly (>80%) by a clathrin-independent, caveolar-related mechanism, regardless of cell type. In addition, fluorescent lactosylceramide (LacCer) colocalized with DsRed-cav-1 in vesicular structures upon endocytosis in rat fibroblasts. The internalization mechanism for GSLs was unaffected by varying the carbohydrate headgroup or sphingosine backbone chain length; however, a fluorescent phosphatidylcholine analog was not internalized via caveolae, suggesting that the GSL ceramide core may be important for caveolar uptake. Internalization of fluorescent LacCer was reduced 80–90% in cell types with low cav-1, but was dramatically stimulated by cav-1 overexpression. However, even in cells with low levels of cav-1, residual LacCer internalization was clathrin independent. In contrast, cholera toxin B subunit (CtxB), which binds endogenous GM1, was internalized via clathrin-independent endocytosis in cells with high cav-1 expression, whereas significant clathrin-dependent uptake occurred in cells with low cav-1. Fluorescent GM1, normally internalized by clathrin-independent endocytosis in HeLa cells with low cav-1, was induced to partially internalize via the clathrin pathway in the presence of CtxB. These results suggest that GSL analogs are selectively internalized via a caveolar-related mechanism in most cell types, whereas CtxB may undergo “pathway switching” when cav-1 levels are low.
37
Thiery, Jerome, Dennis Keefe, Saviz Saffarian, et al. "Perforin activates clathrin- and dynamin-dependent endocytosis, which is required for plasma membrane repair and delivery of granzyme B for granzyme-mediated apoptosis." Blood 115, no. 8 (2010): 1582–93. http://dx.doi.org/10.1182/blood-2009-10-246116.
Full textAbstract:
Abstract Cytotoxic T lymphocytes and natural killer cells destroy target cells via the polarized exocytosis of lytic effector proteins, perforin and granzymes, into the immunologic synapse. How these molecules enter target cells is not fully understood. It is debated whether granzymes enter via perforin pores formed at the plasma membrane or whether perforin and granzymes are first endocytosed and granzymes are then released from endosomes into the cytoplasm. We previously showed that perforin disruption of the plasma membrane induces a transient Ca2+ flux into the target cell that triggers a wounded membrane repair response in which lysosomes and endosomes donate their membranes to reseal the damaged membrane. Here we show that perforin activates clathrin- and dynamin-dependent endocytosis, which removes perforin and granzymes from the plasma membrane to early endosomes, preserving outer membrane integrity. Inhibiting clathrin- or dynamin-dependent endocytosis shifts death by perforin and granzyme B from apoptosis to necrosis. Thus by activating endocytosis to preserve membrane integrity, perforin facilitates granzyme uptake and avoids the proinflammatory necrotic death of a membrane-damaged cell.
38
Shakor, Abo Bakr Abdel, Makoto Taniguchi, Kazuyuki Kitatani, et al. "Sphingomyelin Synthase 1-generated Sphingomyelin Plays an Important Role in Transferrin Trafficking and Cell Proliferation." Journal of Biological Chemistry 286, no. 41 (2011): 36053–62. http://dx.doi.org/10.1074/jbc.m111.228593.
Full textAbstract:
Transferrin (Tf) endocytosis and recycling are essential for iron uptake and the regulation of cell proliferation. Tf and Tf receptor (TfR) complexes are internalized via clathrin-coated pits composed of a variety of proteins and lipids and pass through early endosomes to recycling endosomes. We investigated the role of sphingomyelin (SM) synthases (SMS1 and SMS2) in clathrin-dependent trafficking of Tf and cell proliferation. We employed SM-deficient lymphoma cells that lacked SMSs and that failed to proliferate in response to Tf. Transfection of SMS1, but not SMS2, enabled these cells to incorporate SM into the plasma membrane, restoring Tf-mediated proliferation. SM-deficient cells showed a significant reduction in clathrin-dependent Tf uptake compared with the parental SM-producing cells. Both SMS1 gene transfection and exogenous short-chain SM treatment increased clathrin-dependent Tf uptake in SM-deficient cells, with the Tf being subsequently sorted to Rab11-positive recycling endosomes. We observed trafficking of the internalized Tf to late/endolysosomal compartments, and this was not dependent on the clathrin pathway in SM-deficient cells. Thus, SMS1-mediated SM synthesis directs Tf-TfR to undergo clathrin-dependent endocytosis and recycling, promoting the proliferation of lymphoma cells.
39
Augustine, G. J., J. R. Morgan, C. A. Villalba-Galea, S. Jin, K. Prasad, and E. M. Lafer. "Clathrin and synaptic vesicle endocytosis: studies at the squid giant synapse." Biochemical Society Transactions 34, no. 1 (2006): 68–72. http://dx.doi.org/10.1042/bst0340068.
Full textAbstract:
The role of clathrin-mediated endocytosis in SV (synaptic vesicle) recycling has been studied by combining molecular biology, physiology and electron microscopy at the squid giant synapse. Procedures that prevent clathrin from assembling into membrane coats, such as impairment of binding of the AP180 and AP-2 adaptor proteins, completely prevent membrane budding during endocytosis. These procedures also reduce exocytosis, presumably an indirect effect of a reduction in the number of SVs following block of endocytosis. Disrupting the binding of auxilin to Hsc70 (heat-shock cognate 70) prevents clathrin-coated vesicles from uncoating and also disrupts SV recycling. Taken together, these results indicate that a clathrin-dependent pathway is the primary means of SV recycling at this synapse under physiological conditions.
40
Popova, N. V., I. E. Deyev, and A. G. Petrenko. "Clathrin-Mediated Endocytosis and Adaptor Proteins." Acta Naturae 5, no. 3 (2013): 62–73. http://dx.doi.org/10.32607/20758251-2013-5-3-62-73.
Full textAbstract:
Macromolecules gain access to the cytoplasm of eukaryotic cells using one of several ways of which clathrin-dependent endocytosis is the most researched. Although the mechanism of clathrin-mediated endocytosis is well understood in general, novel adaptor proteins that play various roles in ensuring specific regulation of the mentioned process are being discovered all the time. This review provides a detailed account of the mechanism of clathrin-mediated internalization of activated G protein-coupled receptors, as well as a description of the major proteins involved in this process.
41
Liu, Jiang, and Joseph I. Shapiro. "Endocytosis and Signal Transduction: Basic Science Update." Biological Research For Nursing 5, no. 2 (2003): 117–28. http://dx.doi.org/10.1177/1099800403256860.
Full textAbstract:
Endocytosis can be separated into the categories of phagocytosis and pinocytosis. Phagocytosis can be distinguished from pinocytosis primarily by the size of particle ingested and by its dependence on actin polymerization as a key step in particle ingestion. Several specific forms of pinocytosis have been identified that can be distinguished based on their dependence on clathrin or caveolin. Both clathrin and caveolin-dependent pinocytosis appear to require the participation of dynamin to internalize the plasma membrane. Other, less well-characterized forms of pinocytosis have also been described. Although endocytosis has long been known to affect receptor density, recent studies have demonstrated that endocytosis through clathrin- and caveolin-dependent processes plays a key role in receptor-mediated signal transduction. In some cases, blockade of these processes attenuates, or even prevents, signal transduction from taking place. This information, coupled with a better understanding of endocytosis mechanisms, will help advance the field of cell biology as well as present new targets for drug development and disease treatment.
42
Bouchard, Beth A., Natalie T. Meisler, Michael E. Nesheim, and Paula B. Tracy. "Uptake of Factor V by Megakaryocytes Requires a Specific Factor V Receptor Linked to a Low-Density Lipoprotein Receptor-Related Protein." Blood 106, no. 11 (2005): 688. http://dx.doi.org/10.1182/blood.v106.11.688.688.
Full textAbstract:
Abstract Factor V is endocytosed by megakaryocytes from plasma to form the platelet-derived factor V/Va pool via a receptor-mediated, clathrin-dependent mechanism. However, the megakaryocyte receptor that mediates the binding and subsequent endocytosis of plasma-derived factor V is unknown. Because of its known ability to interact with proteins involved in coagulation and fibrinolysis, the role of low-density lipoprotein receptor-related protein (LRP) or an LRP-like molecule was examined in factor V endocytosis by the megakaryocyte-like cell line CMK. As endocytosis by such proteins is Ca2+-dependent, binding and endocytosis of factor V ± added Ca2+ were examined. While endocytosis of factor V was absolutely dependent upon the presence of Ca2+, binding of factor V to megakaryocytes was unaffected by its absence allowing for the quantification of 125I-factor V binding in the absence of factor V endocytosis. The time-dependent, specific 125I-factor V binding to megakaryocytes reached a steady-state within 20–25 min and displayed a sigmoidal character. The steady state binding of a plasma concentration of 125I-factor V could be displaced 56.4 ± 7.8% by the addition of a 150-fold molar excess of the LRP ligand, receptor associated protein (RAP). In contrast, nearly all of the 125I-factor V bound could be displaced following the addition of a 50-fold molar excess of factor V alone or by the addition of both factor V and RAP. These observations suggest that factor V binds to two binding sites on megakaryocytes, which consist of a specific factor V receptor and LRP (or an LRP-like molecule). This notion of a two-receptor system was confirmed in steady state, concentration-dependent binding analyses of 125I-factor V in the presence or absence of RAP. Binding of factor V was saturable at a concentration ~15–20 times higher than the plasma concentration of factor V, which is consistent with observations that the platelet-derived factor V concentration is dependent upon and parallels the plasma-derived factor V concentration. Similar to the observations described above, concentration-dependent binding was also inhibited 40–50% by the presence of excess RAP. The binding curves in the presence or absence of RAP remained sigmoidal and were fit with confidence (r ≥ 0.95) to a two-receptor binding model. In support of these observations, AlexaFluor488-labeled factor V and AlexaFluor633-labeled RAP co-localized within the same cells subsequent to their endocytosis by megakaryocytes as demonstrated by confocal microscopy. Flow cytometric analyses of the same cell population confirmed these observations: All of the cells that endocytosed factor V also endocytosed RAP. Based upon the combined observations we propose a binding model where factor V endocytosis is mediated by a two-receptor system consisting of a specific factor V receptor and an LRP co-receptor closely linked on the cell surface. In this model, factor V binds to its specific receptor in a Ca2+-independent manner. Bound factor V is then transferred to LRP (or an LRP-like molecule) to allow for the binding of a second factor V molecule to the unoccupied site on the factor V receptor. Factor V bound to LRP is then endocytosed in Ca2+- and clathrin-dependent manners. As our flow cytometric analyses indicate that all of the cells bind and endocytose RAP, we hypothesize that it is the presence or absence of the specific factor V receptor that defines the megakaryocytes’ ability to endocytose factor V from plasma.
43
Ivanova, Margarita M., Julia Dao, Neil Kasaci, Benjamin Adewale, Jacqueline Fikry та Ozlem Goker-Alpan. "Rapid Clathrin-Mediated Uptake of Recombinant α-Gal-A to Lysosome Activates Autophagy". Biomolecules 10, № 6 (2020): 837. http://dx.doi.org/10.3390/biom10060837.
Full textAbstract:
Enzyme replacement therapy (ERT) with recombinant alpha-galactosidase A (rh-α-Gal A) is the standard treatment for Fabry disease (FD). ERT has shown a significant impact on patients; however, there is still morbidity and mortality in FD, resulting in progressive cardiac, renal, and cerebrovascular pathology. The main pathway for delivery of rh-α-Gal A to lysosome is cation-independent mannose-6-phosphate receptor (CI-M6PR) endocytosis, also known as insulin-like growth factor 2 receptor (IGF2R) endocytosis. This study aims to investigate the mechanisms of uptake of rh-α-Gal-A in different cell types, with the exploration of clathrin-dependent and caveolin assisted receptor-mediated endocytosis and the dynamics of autophagy-lysosomal functions. rh-α-Gal-A uptake was evaluated in primary fibroblasts, urine originated kidney epithelial cells, and peripheral blood mononuclear cells derived from Fabry patients and healthy controls, and in cell lines HEK293, HTP1, and HUVEC. Uptake of rh-α-Gal-A was more efficient in the cells with the lowest endogenous enzyme activity. Chloroquine and monensin significantly blocked the uptake of rh-α-Gal-A, indicating that the clathrin-mediated endocytosis is involved in recombinant enzyme delivery. Alternative caveolae-mediated endocytosis coexists with clathrin-mediated endocytosis. However, clathrin-dependent endocytosis is a dominant mechanism for enzyme uptake in all cell lines. These results show that the uptake of rh-α-Gal-A occurs rapidly and activates the autophagy-lysosomal pathway.
44
Sun, Tian-Xiao, Alfred Van Hoek, Yan Huang, Richard Bouley, Margaret McLaughlin, and Dennis Brown. "Aquaporin-2 localization in clathrin-coated pits: inhibition of endocytosis by dominant-negative dynamin." American Journal of Physiology-Renal Physiology 282, no. 6 (2002): F998—F1011. http://dx.doi.org/10.1152/ajprenal.00257.2001.
Full textAbstract:
Before the identification of aquaporin (AQP) proteins, vasopressin-regulated “water channels” were identified by freeze-fracture electron microscopy as aggregates or clusters of intramembraneous particles (IMPs) on hormonally stimulated target cell membranes. In the kidney collecting duct, these IMP clusters were subsequently identified as possible sites of clathrin-coated pit formation on the plasma membrane, and a clathrin-mediated mechanism for internalization of vasopressin-sensitive water channels was suggested. Using an antibody raised against the extracellular C loop of AQP2, we now provide direct evidence that AQP2 is concentrated in clathrin-coated pits on the apical surface of collecting duct principal cells. Furthermore, by using a fracture-label technique applied to LLC-PK1cells expressing an AQP2- c-myc construct, we show that AQP2 is located in IMP aggregates and is concentrated in shallow membrane invaginations on the surface of forskolin-stimulated cells. We also studied the functional role of clathrin-coated pits in AQP2 trafficking by using a GTPase-deficient dynamin mutation (K44A) to inhibit clathrin-mediated endocytosis. Immunofluorescence labeling and freeze-fracture electron microscopy showed that dominant-negative dynamin 1 and dynamin 2 mutants prevent the release of clathrin-coated pits from the plasma membrane and induce an accumulation of AQP2 on the plasma membrane of AQP2-transfected cells. These data provide the first direct evidence that AQP2 is located in clathrin-coated pits and show that AQP2 recycles between the plasma membrane and intracellular vesicles via a dynamin-dependent endocytotic pathway. We propose that the IMP clusters previously associated with vasopressin action represent sites of dynamin-dependent, clathrin-mediated endocytosis in which AQP2 is concentrated before internalization.
45
Teckchandani, Anjali, Erin E. Mulkearns, Timothy W. Randolph, Natalie Toida та Jonathan A. Cooper. "The clathrin adaptor Dab2 recruits EH domain scaffold proteins to regulate integrin β1 endocytosis". Molecular Biology of the Cell 23, № 15 (2012): 2905–16. http://dx.doi.org/10.1091/mbc.e11-12-1007.
Full textAbstract:
Endocytic adaptor proteins facilitate cargo recruitment and clathrin-coated pit nucleation. The prototypical clathrin adaptor AP2 mediates cargo recruitment, maturation, and scission of the pit by binding cargo, clathrin, and accessory proteins, including the Eps-homology (EH) domain proteins Eps15 and intersectin. However, clathrin-mediated endocytosis of some cargoes proceeds efficiently in AP2-depleted cells. We found that Dab2, another endocytic adaptor, also binds to Eps15 and intersectin. Depletion of EH domain proteins altered the number and size of clathrin structures and impaired the endocytosis of the Dab2- and AP2-dependent cargoes, integrin β1 and transferrin receptor, respectively. To test the importance of Dab2 binding to EH domain proteins for endocytosis, we mutated the EH domain–binding sites. This mutant localized to clathrin structures with integrin β1, AP2, and reduced amounts of Eps15. Of interest, although integrin β1 endocytosis was impaired, transferrin receptor internalization was unaffected. Surprisingly, whereas clathrin structures contain both Dab2 and AP2, integrin β1 and transferrin localize in separate pits. These data suggest that Dab2-mediated recruitment of EH domain proteins selectively drives the internalization of the Dab2 cargo, integrin β1. We propose that adaptors may need to be bound to their cargo to regulate EH domain proteins and internalize efficiently.
46
Bouley, Richard, Naofumi Yui, Abby Terlouw, Pui W. Cheung, and Dennis Brown. "Chlorpromazine Induces Basolateral Aquaporin-2 Accumulation via F-Actin Depolymerization and Blockade of Endocytosis in Renal Epithelial Cells." Cells 9, no. 4 (2020): 1057. http://dx.doi.org/10.3390/cells9041057.
Full textAbstract:
We previously showed that in polarized Madin–Darby canine kidney (MDCK) cells, aquaporin-2 (AQP2) is continuously targeted to the basolateral plasma membrane from which it is rapidly retrieved by clathrin-mediated endocytosis. It then undertakes microtubule-dependent transcytosis toward the apical plasma membrane. In this study, we found that treatment with chlorpromazine (CPZ, an inhibitor of clathrin-mediated endocytosis) results in AQP2 accumulation in the basolateral, but not the apical plasma membrane of epithelial cells. In MDCK cells, both AQP2 and clathrin were concentrated in the basolateral plasma membrane after CPZ treatment (100 µM for 15 min), and endocytosis was reduced. Then, using rhodamine phalloidin staining, we found that basolateral, but not apical, F-actin was selectively reduced by CPZ treatment. After incubation of rat kidney slices in situ with CPZ (200 µM for 15 min), basolateral AQP2 and clathrin were increased in principal cells, which simultaneously showed a significant decrease of basolateral compared to apical F-actin staining. These results indicate that clathrin-dependent transcytosis of AQP2 is an essential part of its trafficking pathway in renal epithelial cells and that this process can be inhibited by selectively depolymerizing the basolateral actin pool using CPZ.
47
Llorente, A., K. Prydz, M. Sprangers, G. Skretting, S. O. Kolset, and K. Sandvig. "Proteoglycan synthesis is increased in cells with impaired clathrin-dependent endocytosis." Journal of Cell Science 114, no. 2 (2001): 335–43. http://dx.doi.org/10.1242/jcs.114.2.335.
Full textAbstract:
Overexpression of a GTPase deficient dynamin mutant in HeLa dynK44A cells causes a block in clathrin-dependent endocytosis. When endocytosis is inhibited, these cells incorporate higher levels of [(35)S]sulfate into both cellular and secreted macromolecules and larger amounts of proteoglycans such as syndecan and perlecan are immunoprecipitated from [(35)S]sulfate-labelled lysates. Gel filtration and ion-exchange chromatography revealed that the increased [(35)S]sulfate incorporation into proteoglycans was not due to significant differences in size or density of negative charge of glycosaminoglycan chains attached to proteoglycan core proteins. On the other hand, measurements of the syndecan-1 mRNA level and of [(3)H]leucine-labelled perlecan after immunoprecipitation supported the idea that the increased [(35)S]sulfate incorporation into proteoglycans was due to a selective increase in the synthesis of proteoglycan core proteins. Interestingly, the activity of protein kinase C was increased in cells expressing mutant dynamin and inhibition of protein kinase C with BIM reduced the differences in [(35)S]sulfate incorporation between cells with normal and impaired clathrin-dependent endocytosis. Thus, the activation of protein kinase C observed upon inhibition of clathrin-dependent endocytosis may be responsible for the increased synthesis of proteoglycans.
48
Boleti, H., A. Benmerah, D. M. Ojcius, N. Cerf-Bensussan, and A. Dautry-Varsat. "Chlamydia infection of epithelial cells expressing dynamin and Eps15 mutants: clathrin-independent entry into cells and dynamin-dependent productive growth." Journal of Cell Science 112, no. 10 (1999): 1487–96. http://dx.doi.org/10.1242/jcs.112.10.1487.
Full textAbstract:
Chlamydiae enter epithelial cells via a mechanism that still remains to be fully elucidated. In this study we investigated the pathway of entry of C. psittaci GPIC and C. trachomatis LGV/L2 into HeLa cells and demonstrated that it does not depend on clathrin coated vesicle formation. We used mutant cell lines defective in clathrin-mediated endocytosis due to overexpression of dominant negative mutants of either dynamin I or Eps15 proteins. When clathrin-dependent endocytosis was inhibited by overexpression of the dynK44A mutant of dynamin I (defective in GTPase activity), Chlamydia entry was not affected. However, in these cells there was a dramatic inhibition in the proliferation of Chlamydia and the growth of the chlamydia vacuole (inclusion). When clathrin-dependent endocytosis was inhibited by overexpression of an Eps15 dominant negative mutant, the entry and growth of Chlamydia was unaltered. These results indicate that the effect on the growth of Chlamydia in the dynK44A cells was not simply due to a deprivation of nutrients taken up by endocytosis. Instead, the dominant-negative mutant of dynamin most likely affects the vesicular traffic between the Chlamydia inclusion and intracellular membrane compartments. In addition, cytochalasin D inhibited Chlamydia entry by more than 90%, indicating that chlamydiae enter epithelial cells by an actin-dependent mechanism resembling phagocytosis. Finally, dynamin is apparently not involved in the formation of phagocytic vesicles containing Chlamydia.
49
Gao, Jin, Ajeet Chaudhary, Prasad Vaddepalli, Marie-Kristin Nagel, Erika Isono, and Kay Schneitz. "The Arabidopsis receptor kinase STRUBBELIG undergoes clathrin-dependent endocytosis." Journal of Experimental Botany 70, no. 15 (2019): 3881–94. http://dx.doi.org/10.1093/jxb/erz190.
Full textAbstract:
AbstractSignaling mediated by cell surface receptor kinases is central to the coordination of growth patterns during organogenesis. Receptor kinase signaling is in part controlled through endocytosis and subcellular distribution of the respective receptor kinase. For the majority of plant cell surface receptors, the underlying trafficking mechanisms are not characterized. In Arabidopsis, tissue morphogenesis requires the atypical receptor kinase STRUBBELIG (SUB). Here, we studied the endocytic mechanism of SUB. Our data revealed that a functional SUB–enhanced green fluorescent protein (EGFP) fusion is ubiquitinated in vivo. We further showed that plasma membrane-bound SUB:EGFP becomes internalized in a clathrin-dependent fashion. We also found that SUB:EGFP associates with the trans-Golgi network and accumulates in multivesicular bodies and the vacuole. Co-immunoprecipitation experiments revealed that SUB:EGFP and clathrin are present within the same protein complex. Our genetic analysis showed that SUB and CLATHRIN HEAVY CHAIN (CHC) 2 regulate root hair patterning. By contrast, genetic reduction of CHC activity ameliorates the floral defects of sub mutants. Taken together, the data indicate that SUB undergoes clathrin-mediated endocytosis, that this process does not rely on stimulation of SUB signaling by an exogenous agent, and that SUB genetically interacts with clathrin-dependent pathways in a tissue-specific manner.
50
Choi, Shinkyu, Ji Aee Kim, Seikwan Oh, Mi Hye Park, Geum Joon Cho, and Suk Hyo Suh. "Internalization and Transportation of Endothelial Cell Surface KCa2.3 and KCa3.1 in Normal Pregnancy and Preeclampsia." Oxidative Medicine and Cellular Longevity 2019 (November 23, 2019): 1–13. http://dx.doi.org/10.1155/2019/5820839.
Full textAbstract:
Altered redox state modulates the expression levels of endothelial KCa2.3 and KCa3.1 (KCas) in normal pregnancy (NP) and preeclampsia (PE), thereby regulating vascular contractility. The mechanisms underlying KCas endocytosis and transportation remain unknown. We investigated the regulation of KCas expression in plasma membrane (PM) during NP and PE. Cultured human uterine artery endothelial cells were incubated in serum from normal nonpregnant women and women with NP or PE, or in oxidized LDL-, or lysophosphatidylcholine- (LPC-) containing a medium for 24 hours. NP serum elevated PM levels of KCas and reduced caveolin-1 and clathrin levels. PE serum, oxidized LDL, or LPC reduced PM levels of KCas and elevated caveolin-1, clathrin, Rab5c, and early endosome antigen-1 (EEA1) levels. Reduced KCas levels by PE serum or LPC were reversed by inhibition of caveolin-1, clathrin, or EEA1. Catalase and glutathione peroxidase 1 (GPX1) knockdown elevated PM-localized KCas levels and reduced caveolin-1 and clathrin levels. Elevated KCa2.3 levels upon catalase and GPX1 knockdown were reversed by PEG-catalase treatment. An H2O2 donor reduced clathrin and Rab5c. In contrast, elevated clathrin, caveolin-1, or colocalization of caveolin-1 with KCa3.1 by PE serum or LPC was reversed by NADPH oxidase inhibitors or antioxidants. A superoxide donor xanthine+xanthine oxidase elevated caveolin-1 or Rab5c levels. We concluded that KCas are endocytosed in a caveola- or a clathrin-dependent manner and transported in a Rab5c- and EEA1-dependent manner during pregnancy. The endocytosis and transportation processes may slow down via H2O2-mediated pathways in NP and may be accelerated via superoxide-mediated pathways in PE.