Premium
Different effects of ezrin on apical calcium entry channels
Author(s) -
Jiang Yi,
Peng JiBin
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a350-b
Subject(s) - ezrin , chemistry , microbiology and biotechnology , calcium , cytoskeleton , apical membrane , calcium channel , actin cytoskeleton , biophysics , biology , biochemistry , membrane , cell , organic chemistry
Epithelial calcium channels CaT1 and ECaC, also know as TRPV6 and TRPV5, localize in the apical membrane of the intestine and the distal tubule of the kidney, respectively. Ezrin is a cytoskeletal component beneath the apical membrane of epithelial cells and is an important linker between membrane proteins and F‐actin based cytoskeleton. As there is a potential interaction between ezrin and the apical calcium channels, we examined to what extent the calcium transport activities of the two channels are affected by ezrin using radiotracer calcium uptake assay in Xenopus laevis oocytes. CaT1‐mediated calcium uptake was only modestly inhibited by less than 15% in the presence of ezrin. In contrast, ECaC‐mediated calcium uptake was decreased by 50% in the presence of ezrin. The T567D mutant of ezrin, which mimics the phosphorylated state, exhibited no significant effects on CaT1 and ECaC activity. On the other hand, the nonphosphorylatable T567A mutant of ezrin, which forms oligomers and is poorly associated with cytoskeleton, exhibited inhibitory effects on CaT1 and ECaC to a similar extent as the wild‐type ezrin. TRPV4, which is localized in the basolateral membrane in renal tubules, was also regulated by ezrin and its mutants to an extent similarly to that for ECaC. These results suggest that ezrin inhibit the calcium channels in its oligomer form unassociated with cytoskeleton. The tissue distribution of ezrin overlaps mostly with that of CaT1. The least inhibitory effect of ezrin on CaT1 implies that ezrin does not significantly affect the function of CaT1. Supported in part by American Heart Association.