Src family kinases inhibit differentiation of intestinal epithelial cells through the Hippo effector YAP1

Sepideh Fallah,Jean-François Beaulieu

doi:10.1242/bio.058904

Abstract

ABSTRACTIntestinal cell lineage differentiation is a tightly regulated mechanism that involves several intracellular signaling pathways affecting the expression of a variety of transcription factors, which ultimately regulate cell specific gene expression. Absorptive and goblet cells are the two main epithelial cell types of the intestine. Previous studies from our group using an shRNA knockdown approach have shown that YAP1, one of the main Hippo pathway effectors, inhibits the differentiation of these two cell types. In the present study, we show that YAP1 activity is regulated by Src family kinases (SFKs) in these cells. Inhibition of SFKs led to a sharp reduction in YAP1 expression at the protein level, an increase in CDX2 and the P1 forms of HNF4α and of absorptive and goblet cell differentiation specific markers. Interestingly, in Caco-2/15 cells which express both YAP1 and its paralog TAZ, TAZ was not reduced by the inhibition of SFKs and its specific knockdown rather impaired absorptive cell differentiation indicating that YAP1 and TAZ are not always interchangeable for regulating cell functions.This article has an associated First Person interview with the first author of the paper.

Highlights

The intestinal epithelium which covers the inner layer of the mammalian intestinal lumen is characterized by its rapid renewal properties
We show that Yes associated protein 1 (YAP1) activity is regulated by Src family kinases (SFKs) in these cells
Inhibition of SFKs led to a sharp reduction in YAP1 expression at the protein level, an increase in caudal type homeobox 2 (CDX2) and the P1 forms of HNF4α and of absorptive and goblet cell differentiation specific markers

Summary

Introduction

The intestinal epithelium which covers the inner layer of the mammalian intestinal lumen is characterized by its rapid renewal properties. It is composed of different cell types including crypt base columnar (CBC) stem cells, a subpopulation of quiescent stem cells, proliferating cells and post mitotic differentiated cells, all located in the crypts, which give rise to two distinct cell lineages, absorptive and secretory (Roostaee et al, 2016). Knockdown of YAP1 was accompanied by an increase in the expression of caudal type homeobox 2 (CDX2) transcription factor (Fallah and Beaulieu, 2020), which is one of the master transcription factors for intestinal epithelial cell differentiation. The ectopic expression of CDX2 in undifferentiated normal rat and human crypt cells resulted in impaired proliferation and the generation of absorptive and goblet-like cells (Suh and Traber, 1996; Escaffit et al, 2006)

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