Claudin 11 ELISA Kit

Objective: Claudins are a family of membrane proteins which localize to tight junctions (TJs). Recent studies have shown that claudins can form pores for ions in the TJs and regulate the permeability of epithelial paracellular ion transport. The endolymphatic sac (ES) is a part of the inner ear, absorbing the endolymphatic fluid. ES dysfunction may result in endolymphatic hydrops. In this study, we focused on the paracellular transport and examined claudin mRNA expression in the ES epithelia. Materials and methods: Total RNA was isolated from whole ES epithelia of rats by laser capture microdissection. RT-PCR was used to evaluate the expression of claudins. The expression of each claudin mRNA in the epithelial cells of rat ES was confirmed by in situ hybridization. Results: RT-PCR indicated the expression of cldn2, cldn4, cldn6, cldn7, cldn9, cldn11, cldn12, and cldn14. The expression of these claudin mRNAs in the epithelial cells of rat ES was confirmed by in situ hybridization. Conclusion: We demonstrated mRNA expression of multiple claudirs in the rat ES epithelia. These results in the ES epithelia were consistent with a role of claudins in paracellular ion transport. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

It is widely recognized that the claudin (Cldn) family of four tetraspan transmembrane proteins is crucial for tight junction assembly and permeability barrier function; however, the precise role of the tail and loop domains in Cldn function is not understood. We hypothesized that the cytoplasmic tail domain of Cldn6 is crucial for membrane targeting and hence epidermal permeability barrier (EPB) formation. To test this hypothesis via a structure-function approach, we generated a tail deletion of Cldn6 (C Delta 187) and evaluated its role in epidermal differentiation and EPB formation through its forced expression via the involucrin (Inv) promoter in the suprabasal compartment of the transgenic mouse epidermis. Even though a functional barrier formed, Inv-C Delta 187 mice displayed histological and biochemical abnormalities in the epidermal differentiation program and stimulation of epidermal cell proliferation in both the basal and suprabasal compartments of the interfolliclar epidermis, leading to a thickening of the epidermis after 1 week of age that persisted throughout life. Although some membrane localization was evident, our studies also revealed a significant amount of not only Cldn6 but also Cldn10, Cldn11, and Cldn18 in the cytoplasm of transgenic epidermal cells as well as the activation of a protein-unfolding pathway. These findings demonstrate that the overexpression of a tail truncation mutant of Cldn6 mislocalizes Cldn6 and other Cldn proteins to the cytoplasm and triggers a postnatal increase in proliferation and aberrant differentiation of the epidermis, emphasizing the importance of the Cldn tail domain in membrane targeting and function in vivo.