TEAD transcription factors are required for normal primary myoblast differentiation in vitro and muscle regeneration in vivo.

Shilpy Joshi,Stéphanie Le Gras,Irwin Davidson,Thomas Braun,Gabrielle Mengus,Guillaume Davidson,Shuichi Watanabe,Gregory S Barsh

doi:10.1371/journal.pgen.1006600

Abstract

The TEAD family of transcription factors (TEAD1-4) bind the MCAT element in the regulatory elements of both growth promoting and myogenic differentiation genes. Defining TEAD transcription factor function in myogenesis has proved elusive due to overlapping expression of family members and their functional redundancy. We show that silencing of either Tead1, Tead2 or Tead4 did not effect primary myoblast (PM) differentiation, but that their simultaneous knockdown strongly impaired differentiation. In contrast, Tead1 or Tead4 silencing impaired C2C12 differentiation showing their different contributions in PMs and C2C12 cells. Chromatin immunoprecipitation identified enhancers associated with myogenic genes bound by combinations of Tead4, Myod1 or Myog. Tead4 regulated distinct gene sets in C2C12 cells and PMs involving both activation of the myogenic program and repression of growth and signaling pathways. ChIP-seq from mature mouse muscle fibres in vivo identified a set of highly transcribed muscle cell-identity genes and sites bound by Tead1 and Tead4. Although inactivation of Tead4 in mature muscle fibres caused no obvious phenotype under normal conditions, notexin-induced muscle regeneration was delayed in Tead4 mutants suggesting an important role in myogenic differentiation in vivo. By combining knockdown in cell models in vitro with Tead4 inactivation in muscle in vivo, we provide the first comprehensive description of the specific and redundant roles of Tead factors in myogenic differentiation.

Highlights

The TEAD(1–4) transcription factors [1, 2] bind to a consensus MCAT (5’-CATTCCA/T-3’) element, originally identified as the SV40 enhancer GT-II motif [3] [4,5,6], through the evolutionarily conserved TEA/ATTS DNA binding domain [7, 8]
Using integrative genomics and knockdowns in cell based models, we show that Tead factors are essential for differentiation of C2C12 cells and primary myoblasts, but make different contributions activating a distinct set of myogenesis genes in each cell type
We previously showed that Tead4 plays an essential role in C2C12 cell differentiation [21]

Summary

Introduction

The TEAD(1–4) transcription factors [1, 2] bind to a consensus MCAT (5’-CATTCCA/T-3’) element, originally identified as the SV40 enhancer GT-II motif [3] [4,5,6], through the evolutionarily conserved TEA/ATTS DNA binding domain [7, 8]. Tead factors act as mediators of the Hippo signalling pathway interacting with the Yap and Wwtr (Taz) transcriptional co-activators to regulate proliferation, oncogenesis, stem cell maintenance and differentiation and control of organ size [9,10,11,12,13,14]. Teads play an important role in skeletal, cardiac, and smooth muscle differentiation and physiology [15,16,17,18]. Blais et al showed that Myod and Myog directly bind the Tead promoter and activate its expression during C2C12 cell differentiation in vitro [20]. While our data described a role for Tead in activating muscle genes during differentiation, we suggested that Tead may repress Ctgf and Ccnd expression contributing to cell cycle exit.

Methods

Results

Conclusion