Academic literature on the topic 'Knockin mouse model'

Abstract CD1d-restricted natural killer T (NKT) cells regulate the immune system in response to a broad range of diseases. The CD1d/NKT antigen presentation pathway is largely conserved between human and mouse, however, there is distinct difference between the two species. To better study human CD1d antigen presentation in an in vivo setting, we have generated a human CD1d knock-in (KI) mouse. We have expressed human CD1d (hCD1d) in place of mouse CD1d (mCD1d). The expression of hCD1d was verified on CD4+CD8+DP thymocytes and thymic dendritic cells, which are involved in NKT cell positive and negative selections, respectively, in thymus. CD1d-α-GalCer tetramer+ invariant NKT (iNKT) cells have been shown in thymus, spleen and liver. However, reduced numbers of iNKT cells were observed in these organs compared to that in wild-type mice. Among these iNKT cells, Vβ8 has been over-represented comparing with wild-type mouse, suggesting hCD1d preferentially selects for mouse Vβ8 chain, which is highly homologous to human Vβ11 chain. In vitro presentation of various glycolipids by BMDCs from hCD1d KI mice showed that hCD1d is functional in presenting different groups of lipids. Furthermore, lipid administration in the KI mice showed that in vivo hCD1d-restricted NKT cells are functional. In summary, our hCD1d KI mouse can be a novel model for in vivo studying hCD1d-specific antigen presentation in antitumor and antimicrobial immunity as well as autoimmune diseases.

Barttin, a gene product of BSND, is one of four genes responsible for Bartter syndrome. Coexpression of barttin with ClC-K chloride channels dramatically induces the expression of ClC-K current via insertion of ClC-K-barttin complexes into plasma membranes. We previously showed that stably expressed R8L barttin, a disease-causing missense mutant, is retained in the endoplasmic reticulum (ER) of Madin-Darby canine kidney (MDCK) cells, with the barttin β-subunit remaining bound to ClC-K α-subunits (Hayama A, Rai T, Sasaki S, Uchida S. Histochem Cell Biol 119: 485–493, 2003). However, transient expression of R8L barttin in MDCK cells was reported to impair ClC-K channel function without affecting its subcellular localization. To investigate the pathogenesis in vivo, we generated a knockin mouse model of Bartter syndrome that carries the R8L mutation. These mice display disease-like phenotypes (hypokalemia, metabolic alkalosis, and decreased NaCl reabsorption in distal tubules) under a low-salt diet. Immunofluorescence and immunoelectron microscopy revealed that the plasma membrane localization of both R8L barttin and the ClC-K channel was impaired in these mice, and transepithelial chloride transport in the thin ascending limb of Henle's loop (tAL) as well as thiazide-sensitive chloride clearance were significantly reduced. This reduction in transepithelial chloride transport in tAL, which is totally dependent on ClC-K1/barttin, correlated well with the reduction in the amount of R8L barttin localized to plasma membranes. These results suggest that the major cause of Bartter syndrome type IV caused by R8L barttin mutation is its aberrant intracellular localization.