Contribution of serum response factor and myocardin to transcriptional regulation of smoothelins

Sander S.M. Rensen, Petra M.G. Niessen, Xiaochun Long, Pieter A. Doevendans, Joseph M. Miano, Guillaume J.J.M. Van Eys

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

Objective: Smoothelin-A and -B isoforms are highly restricted to contractile smooth muscle cells (SMCs). Serum response factor (SRF) and myocardin are essential for contractile SMC differentiation. We evaluated the contribution of SRF/myocardin to transcriptional regulation of smoothelins. Methods: Rat vascular SMCs were transfected with smoothelin-A and smoothelin-B promoter reporter constructs and promoter activity was analyzed. The effects of mutations in the smoothelin-A promoter CArG-boxes and co-transfections with a myocardin expression plasmid were assessed. Electrophoretic mobility shift assays and chromatin immunoprecipitations were performed to investigate SRF-binding to the smoothelin-A CArG-boxes. Results: Smoothelin promoter activity was detected in vascular SMCs. Comparative sequence analysis revealed two conserved CArG elements in the smoothelin-A promoter that bind SRF as shown by chromatin immunoprecipitation. The proximal CArG-near bound SRF stronger than CArG-far in gel shift assays. Mutagenesis studies also indicated that CArG-near is more important than CArG-far in regulating smoothelin-A promoter activity. Myocardin augmented smoothelin-A promoter activity 2.5-fold in a CArG-near-dependent manner. In contrast, myocardin had little effect on the smoothelin-B promoter. Conclusion: Smoothelin-A expression is controlled by an intragenic promoter whose activity is, in part, dependent on two CArG boxes that bind SRF. Our data show a role for SRF/myocardin in regulating smoothelin-A whereas the higher smoothelin-B expression appears to be SRF/myocardin- independent.

Original languageEnglish (US)
Pages (from-to)136-145
Number of pages10
JournalCardiovascular Research
Volume70
Issue number1
DOIs
StatePublished - Apr 1 2006
Externally publishedYes

Keywords

  • Gene expression
  • Myocardin
  • Serum response factor
  • Smooth muscle cell differentiation
  • Smoothelins

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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