Academic literature on the topic 'Arginine-glycine-aspartic acid (RGD)'

ABSTRACT The human parechovirus 1 RGD motif in VP1 was studied by mutagenesis. An RGD-to-RGE change gave only revertant viruses with a restored RGD, while deletion of GD was lethal and nonrevertable. Mutations at the +1 and +2 positions had some effect on growth properties and a +1 M-to-P change was lethal. These studies indicate that the RGD motif plays a critical role in infectivity, presumably by interacting with integrins, and that downstream amino acids can have an influence on function.

Understanding the pathogenesis of drug-induced immune thrombocytopenia is the key to better patient management. In this issue of Blood, Bougie and colleagues provide further useful insights into the mechanism of thrombocytopenia caused by arginine-glycine-aspartic acid (RGD) mimetic drugs.1

Several cell surface proteins (Mr=120,000, 90,000, 63,000 and 47,000) apparently integral to embryonic fibroblast plasma membranes were extracted with detergent and isolated by collagen affinity chromatography. Certain of these proteins (Mr=120,000, 90,000 and 47,000) were specifically eluted from collagen affinity columns by synthetic peptides containing the amino acid sequence arginyl-glycyl-aspartic acid (RGD). These data show that a number of collagen binding proteins exist on the embryonic fibroblast cell surface. Some of the proteins may be collagen receptors binding to RGD sequences in the collagen molecule while at least one of the proteins (Mr=63,000) recognizes features other than RGD.

Osteopontin (OPN), a secretory RGD-containing phosphoprotein, has been identified in cow oviductal ephitelium and fluid, but its role in fertilization is unclear. RGD peptide is capable of blocking fertilization, inducing intracellular Ca2+ transients, and initiating parthenogenetic development when present during bovine fertilization in vitro.This study was conducted to determine whether in vitro sperm binding to the zona pellucida (ZP) and fertilization of bovine oocytes were affected by treating the sperm or oocytes with RGD (arginine–glycine–aspartic acid, a sequence recognized by integrins) or non-RGD-containing peptides. In vitro matured oocytes were incubated (39°C, 5% CO2 in air) for 2 hours in fertilization medium with: (1) no peptides;; (2) 50μgmL−1 RGD (Calbiochem®, San Diego, CA, USA); (3) 1000μgmL−1; (4) 50μgmL−1 non-RGD (Calbiochem®); (5) 1000μgmL−1 non-RGD. The bovine sperm from two differents bulle was collected by artificial vagina, pooled, washed twice with MTM at 500g for 10min and incubated (39°C, 5% CO2 in air) for two h at 5×107 concentration in MTM with: (6) no peptides;; (7) 50μgmL−1 RGD;; (8) 1000μgmL−1; (9) 50μgmL−1 non-RGD; (10) 1000μgmL−1 non-RGD. Following incubation, treated and untreated oocytes were washed and inseminated with 1×105 treated or untreated fresh spermatozoa per 10 oocytes;; after the sperm were recovered from a Percoll gradient (45%/90%). After 18–20h, oocytes were removed from co-culture, and washed in TL-HEPES. Oocytes used to assess sperm binding were stained with Hoescht 33342, and the number of sperm bound per ZP counted. The remaining oocytes were fixed in acid alcohol, stained with 1% acetato-orcein and observed for the presence of pronuclei. For the five replicates, 100–120 oocytes were used for fertilization and 150–170 oocytes were used for sperm-egg binding assays. Data were analized by SAS. Treatment of sperm or oocytes with the RGD peptide significantly decreased (P<0.05) fertilization compared to the non-treated controls or those treated with non-RGD peptides: (1) 80%±3.0; (2) 42%±3.0; (3) 30.2%±3.0; (4) 78.5%±3.0; (5) 79.1%±3.0; (6) 78.9%±3.0; (7) 41.3%±3.0; (8) 29.1%±3.0; (9) 79.2%±3.0; (10) 80.2%±3.0. More sperm bound to the ZP of untreated or non-RGD-treated oocytes or sperm than those incubated with the RGD peptide: (1) 71.2±4.1; (2) 33.2±4.2; (3) 24.2±4.1; (4) 69.5±4.1; (5) 70.2±4.2; (6) 71.9±4.2; (7) 29.8±4.2; (8) 19.8±4.2; (9) 68.9±4.2; (10) 70.6±4.2. These studies demonstrated that incubation of bovine oocytes or spermatozoa with a RGD peptide inhibits sperm-egg binding and fertilization in vitro. These findings support the notion that the role of osteopontin in bovine fertilization may involve inteaction with integrins via its RGD sequence.