Cell-cell contact and matrix adhesion promote αSMA expression during TGFβ1-induced epithelial-myofibroblast transition via Notch and MRTF-A.

Joseph W O’Connor,Clayton Wang,Krunal Mistry,Esther W Gomez,Dayne Detweiler

doi:10.1038/srep26226

Joseph W O’Connor, Clayton Wang + Show 3 more

Open Access

https://doi.org/10.1038/srep26226

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Journal: Scientific Reports	Publication Date: May 19, 2016
Citations: 31	License type: CC BY 4.0

Affiliation: Pennsylvania State University

Abstract

During epithelial-mesenchymal transition (EMT) epithelial cells lose cell-cell adhesion, exhibit morphological changes, and upregulate the expression of cytoskeletal proteins. Previous studies have demonstrated that complete disruption of cell-cell contact can promote transforming growth factor (TGF)-β1-induced EMT and the expression of the myofibroblast marker alpha smooth muscle actin (αSMA). Furthermore, increased cell spreading mediates TGFβ1-induced αSMA expression during EMT. Here, we sought to examine how the presence of partial cell-cell contacts impacts EMT. A microfabrication approach was employed to decouple the effects of cell-cell contact and cell-matrix adhesion in TGFβ1-induced EMT. When cell spreading is controlled, the presence of partial cell-cell contacts enhances expression of αSMA. Moreover, cell spreading and intercellular contacts together control the subcellular localization of activated Notch1 and myocardin related transcription factor (MRTF)-A. Knockdown of Notch1 or MRTF-A as well as pharmacological inhibition of these pathways abates the cell-cell contact mediated expression of αSMA. These data suggest that the interplay between cell-matrix adhesion and intercellular adhesion is an important determinant for some aspects of TGFβ1-induced EMT.

Highlights

Calcium plays important roles in maintenance of cell junctional complexes and serves as a second messenger in a wide variety of signal transduction pathways including gene transcription and contraction[12,13,14,15]
Normal murine mammary gland (NMuMG) epithelial cells were seeded at densities ranging from 500 to 100,000 cells/cm[2] and were treated with TGFβ1 or control vehicle for 48 hours
Cells plated at high densities were refractive to TGFβ1-induction of Epithelial-mesenchymal transition (EMT) while cells cultured at low densities exhibited reduced expression of the epithelial marker E-cadherin and increased expression of the mesenchymal markers vimentin and αSMA (Fig. 1a,b)

Summary

Introduction

Calcium plays important roles in maintenance of cell junctional complexes and serves as a second messenger in a wide variety of signal transduction pathways including gene transcription and contraction[12,13,14,15]. Our recent studies indicate that cell-ECM adhesion and cell spread area are important regulators of the development of myofibroblasts from epithelial cells during TGFβ1-induced EMT16. Intact cell-cell contacts can limit cell spreading and may impact EMT induction and reduce the expression of αSMA It is not clear how partial cell-cell contacts (such as those experienced by cells along a wound edge) and cell-ECM adhesion act in concert to mediate the expression of cytoskeletal proteins and myofibroblast development from epithelial cells. We identify Notch[1] and MRTF-A as important regulators in intercellular adhesion controlled αSMA expression These data suggest that under certain circumstances cell-cell interactions may promote the expression of myofibroblast markers during TGFβ1-induced EMT

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