A Novel Role for Villin in Intestinal Epithelial Cell Survival and Homeostasis

Yaohong Wang,Kamalakkannan Srinivasan,Mohammad Rizwan Siddiqui,Sudeep P George,Alok Tomar,Seema Khurana

doi:10.1074/jbc.m707962200

Yaohong Wang, Kamalakkannan Srinivasan + Show 4 more

Open Access

https://doi.org/10.1074/jbc.m707962200

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Abstract

Apoptosis is a key regulator for the normal turnover of the intestinal mucosa, and abnormalities associated with this function have been linked to inflammatory bowel disease and colorectal cancer. Despite this, little is known about the mechanism(s) mediating intestinal epithelial cell apoptosis. Villin is an actin regulatory protein that is expressed in every cell of the intestinal epithelium as well as in exocrine glands associated with the gastrointestinal tract. In this study we demonstrate for the first time that villin is an epithelial cell-specific anti-apoptotic protein. Absence of villin predisposes mice to dextran sodium sulfate-induced colitis by promoting apoptosis. To better understand the cellular and molecular mechanisms of the anti-apoptotic function of villin, we overexpressed villin in the Madin-Darby canine kidney Tet-Off epithelial cell line to demonstrate that expression of villin protects cells from apoptosis by maintaining mitochondrial integrity thus inhibiting the activation of caspase-9 and caspase-3. Furthermore, we report that the anti-apoptotic response of villin depends on activation of the pro-survival proteins, phosphatidylinositol 3-kinase and phosphorylated Akt. The results of our studies shed new light on the previously unrecognized function of villin in the regulation of apoptosis in the gastrointestinal epithelium.

Highlights

Villin-null Mice Demonstrate Increased Epithelial Cell Apoptosis and Are More Sensitive to dextran sodium sulfate (DSS)-induced Injury—In an effort to examine the in vivo function of villin in intestinal epithelial cell injury, we elected to treat villin-null mice and their wild-type littermates with established protocols to induce DSSinduced colitis, namely 3% DSS dissolved in sterile, distilled drinking water fed ad libitum
Using homozygous villin-null mice, we show unequivocally that the histopathological and clinical changes induced in vivo following DSS treatment were dependent on villin expression
Our data indicate that the degree of apoptosis early in the DSS treatment in the villin-null mice correlated with the severity of colitis subsequently

Summary

Introduction

There was significant weight loss between days 5 and 7 in villin-null mice compared with wild-type littermates following DSS treatment. Apoptotic cells were noted histologically in hematoxylin and eosin sections of proximal and distal colon of wild-type and villin-null mice and the data correlated with the TUNEL assay.

Results

Conclusion