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Activation of intestinal NHE3 by insulin depends on the coordination of IRBIT, NHERF1, and Ezrin
Author(s) -
He Peijian,
Srinivasan Shanthi,
Yun Chris
Publication year - 2013
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.27.1_supplement.1210.11
Subject(s) - ezrin , insulin , chemistry , microbiology and biotechnology , gene knockdown , endocrinology , medicine , biology , cell , biochemistry , apoptosis , cytoskeleton
Diarrhea is one of the troublesome disorders of diabetic intestine, but the cause is not clear. We have shown that NHE3 activity is reduced in streptozotocin (STZ)‐induced diabetic intestine, and insulin treatment restores NHE3 activity. The goal of this study is to determine the mechanisms by which insulin activates intestinal NHE3. We found that expression of NHE3 and IRBIT, but not NHERF1–3 and Ezrin, was significantly decreased in the bush border membrane (BBM) of STZ‐treated mice. Insulin treatment restored BBM expression of NHE3 and IRBIT. In addition, we found by using Proximity Ligation Assay that insulin increased NHE3‐IRBIT, NHERF1‐IRBIT, and NHE3‐NHERF1 interaction in the apical membrane. Importantly, knockdown of either IRBIT or NHERF1 abrogated NHE3 activation in intestinal epithelial SK‐CO15 cells. Insulin also increased Ezrin phosphorylation and its interaction with NHERF1, IRBIT, and NHE3. Moreover, Ezrin was found in the same macromolecular complex with IRBIT, NHERF1 and NHE3 by blue native PAGE analysis, suggesting a role of Ezrin. In conclusion, insulin activates NHE3 trafficking and activity that depends on the formation of a macroprotein complex with IRBIT, NHERF1, and Ezrin.