p38-dependent phosphorylation of the mRNA decay-promoting factor KSRP controls the stability of select myogenic transcripts

Mol Cell. 2005 Dec 22;20(6):891-903. doi: 10.1016/j.molcel.2005.10.021.


Transcriptional and posttranscriptional processes regulate expression of genetic networks in response to environmental cues. The extracellular signal-activated p38 MAP kinase (p38) pathway plays a fundamental role in conversion of myoblasts to differentiated myocytes. p38 phosphorylates specific transcription factors and chromatin-associated proteins promoting assembly of the myogenic transcriptome. Here, we demonstrate that p38 alpha and beta isoforms also control muscle-gene expression posttranscriptionally, by stabilizing critical myogenic transcripts. KSRP, an important factor for AU-rich element (ARE)-directed mRNA decay, undergoes p38-dependent phosphorylation during muscle differentiation. KSRP phosphorylated by p38 displays compromised binding to ARE-containing transcripts and fails to promote their rapid decay, although it retains the ability to interact with the mRNA degradation machinery. Overexpression of KSRP selectively impairs induction of ARE-containing early myogenic transcripts, without affecting p38-mediated transcriptional responses. Our results uncover an unanticipated role for KSRP in establishing a biochemical link between differentiation-activated p38 signaling and turnover of myogenic mRNAs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation / physiology
  • Cell Line
  • Gene Expression Regulation
  • Isoenzymes / genetics
  • Isoenzymes / metabolism
  • Mice
  • Myoblasts / cytology
  • Myoblasts / physiology*
  • Phosphorylation
  • RNA Stability*
  • RNA, Messenger / metabolism*
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism*


  • Isoenzymes
  • KHSRP protein, human
  • KSRP protein, mouse
  • RNA, Messenger
  • RNA, Small Interfering
  • RNA-Binding Proteins
  • Recombinant Proteins
  • Trans-Activators
  • p38 Mitogen-Activated Protein Kinases