CREB Is Activated by Muscle Injury and Promotes Muscle Regeneration

Randi Stewart,Marc Montminy,Lawrence Flechner,Rebecca Berdeaux,Laszlo Tora

doi:10.1371/journal.pone.0024714

Abstract

The cAMP response element binding protein (CREB) plays key roles in differentiation of embryonic skeletal muscle progenitors and survival of adult skeletal muscle. However, little is known about the physiologic signals that activate CREB in normal muscle. Here we show that CREB phosphorylation and target genes are induced after acute muscle injury and during regeneration due to genetic mutation. Activated CREB localizes to both myogenic precursor cells and newly regenerating myofibers within regenerating areas. Moreover, we found that signals from damaged skeletal muscle tissue induce CREB phosphorylation and target gene expression in primary mouse myoblasts. An activated CREB mutant (CREBY134F) potentiates myoblast proliferation as well as expression of early myogenic transcription factors in cultured primary myocytes. Consistently, activated CREB-YF promotes myoblast proliferation after acute muscle injury in vivo and enhances muscle regeneration in dystrophic mdx mice. Our findings reveal a new physiologic function for CREB in contributing to skeletal muscle regeneration.

Highlights

Vertebrate myogenesis is controlled by cascades of muscle-specific transcription factors, which dictate myogenic specification and differentiation, as well as repair of damaged adult skeletal muscle [1]
We show that cAMP response element binding protein (CREB) phosphorylation and target genes are activated in response to skeletal muscle injury and that activated CREB drives myoblast proliferation
To monitor CREB transcriptional activity, we quantified mRNAs of two direct CREB target genes in muscle cells, salt inducible kinase 1 (Sik1) and Nr4a2 [7]. Both of these genes have been previously shown to contain consensus CREB binding sites that are occupied by CREB and phospho-CREB in multiple cell types [13,14,15], including C2C12 myoblasts [7]. Acute induction of these genes is blocked in myoblasts and other cell types by the dominant CREB inhibitor A-CREB [7]

Summary

Introduction

Vertebrate myogenesis is controlled by cascades of muscle-specific transcription factors, which dictate myogenic specification and differentiation, as well as repair of damaged adult skeletal muscle [1]. It is currently unknown what signals induce CREB(S133) phosphorylation in myoblasts within adult skeletal muscle, genetic studies in mice have shown that CREB activity is required for muscle development and survival. Consistent with our results showing phosphorylated CREB in injured skeletal muscle tissue, we found that cardiotoxin treatment induced Sik1 and Nr4a2 mRNAs, which peaked 3 days post-injury (Figure 1B and not shown).

Results

Conclusion