Affiliation:
1. Department of Cardiovascular and Renal Medicine, Saga University Faculty of Medicine, Saga, Japan; and
2. Department of Bioscience and Genetics, National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
Abstract
Tight junctions composed of transmembrane proteins, including claudin, occludin, and tricellulin, and peripheral membrane proteins are a major barrier to endothelial permeability, whereas the role of claudin in the regulation of tight junction permeability in nonneural endothelial cells is unclear. This study demonstrates that claudin-1 is dominantly expressed and depletion of claudin-1 using small interfering RNA (siRNA) increased tight junction permeability in EA hy.926 cells, indicating that claudin-1 is a crucial regulator of endothelial tight junction permeability. The ubiquitin-proteasome system has been implicated in the regulation of endocytotic trafficking of plasma membrane proteins. Therefore, the involvement of proteasomes in the localization of claudin-1 was investigated by pharmacological and genetic inhibition of proteasomes using a proteasome inhibitor, N-acetyl-Leu-Leu-Nle-CHO, and siRNA against the β5-subunit of the 20S proteasome, respectively. Claudin-1 was localized at cell-cell contact sites in control cells. Claudin-1 was localized in the cytoplasm in association with Rab5a and EEA-1, a marker of early endosome, following inhibition of proteasomes. Depletion of Rab5a using siRNA reversed the localization of claudin-1 induced by inhibition of proteasomes. These data suggest that proteasomes regulate claudin-1 localization at the plasma membrane, which changes upon proteasomal inhibition to a Rab5a-mediated endosomal localization.
Publisher
American Physiological Society
Cited by
15 articles.
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