Cofilin-1 Is a Mechanosensitive Regulator of Transcription.

Catarina Domingues,André Matos,Artur Paiva,Sandra Isabel Anjo,João Carvalho,Mário Grãos,Bruno Manadas,A Margarida Geraldo,Inês Caramelo,José A Lopes-Da-Silva,Ricardo Pires Das Neves,Cláudio Almeida

doi:10.3389/fcell.2020.00678

Abstract

The mechanical properties of the extracellular environment are interrogated by cells and integrated through mechanotransduction. Many cellular processes depend on actomyosin-dependent contractility, which is influenced by the microenvironment’s stiffness. Here, we explored the influence of substrate stiffness on the proteome of proliferating undifferentiated human umbilical cord-matrix mesenchymal stem/stromal cells. The relative abundance of several proteins changed significantly by expanding cells on soft (∼3 kPa) or stiff substrates (GPa). Many such proteins are associated with the regulation of the actin cytoskeleton, a major player of mechanotransduction and cell physiology in response to mechanical cues. Specifically, Cofilin-1 levels were elevated in cells cultured on soft comparing with stiff substrates. Furthermore, Cofilin-1 was de-phosphorylated (active) and present in the nuclei of cells kept on soft substrates, in contrast with phosphorylated (inactive) and widespread distribution in cells on stiff. Soft substrates promoted Cofilin-1-dependent increased RNA transcription and faster RNA polymerase II-mediated transcription elongation. Cofilin-1 is part of a novel mechanism linking mechanotransduction and transcription.

Highlights

Cells sense and respond to the mechanical properties of the extracellular environment
This study presents a comparative and quantitative proteomics analysis of hUCM-MSCs cultured on stiff tissue culture polystyrene (TCPS) and soft polydimethylsiloxane (PDMS) substrates, which allowed the identification and characterisation of Cofilin-1 as a mechanosensitive protein involved in the regulation of transcription in response to substrate stiffness
Our results demonstrate that the proteome of hUCM-MSCs presents differences between cells cultured on stiff TCPS or on soft PDMS substrates

Summary

Introduction

Cells sense and respond to the mechanical properties of the extracellular environment. If the stiffness of the extracellular matrix (or substrate if in vitro) is high, the reinforcement of FAs occurs, resulting in increased intracellular contractility and mechanical stress exerted on the ECM and the nucleus (Moore et al, 2010; Klapholz and Brown, 2017). The intrinsic or extrinsic forces occurring as the result of actomyosin contractility as a function of ECM/substrate stiffness, or other mechanical cues provided by the microenvironment influence many aspects of cell biology, including proliferation, differentiation and gene expression (Sun et al, 2012; Discher et al, 2017; Kumar et al, 2017; Uhler and Shivashankar, 2017; Vining and Mooney, 2017)

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