Previous Article | Next Article ![]()
Mol. Cell. Biol., Apr 1997, 2266-2278, Vol 17, No. 4
S Kim, HS Ip, MM Lu, C Clendenin and MS Parmacek
The SM22alpha promoter has been used as a model system to define the
molecular mechanisms that regulate smooth muscle cell (SMC) specific gene
expression during mammalian development. The SM22alpha gene is expressed
exclusively in vascular and visceral SMCs during postnatal development and
is transiently expressed in the heart and somites during embryogenesis.
Analysis of the SM22alpha promoter in transgenic mice revealed that 280 bp
of 5' flanking sequence is sufficient to restrict expression of the lacZ
reporter gene to arterial SMCs and the myotomal component of the somites.
DNase I footprint and electrophoretic mobility shift analyses revealed that
the SM22alpha promoter contains six nuclear protein binding sites
(designated smooth muscle elements [SMEs] -1 to -6, respectively), two of
which bind serum response factor (SRF) (SME-1 and SME-4). Mutational
analyses demonstrated that a two-nucleotide substitution that selectively
eliminates SRF binding to SME-4 decreases SM22alpha promoter activity in
arterial SMCs by approximately 90%. Moreover, mutations that abolish
binding of SRF to SME-1 and SME-4 or mutations that eliminate each SME- 3
binding activity totally abolished SM22alpha promoter activity in the
arterial SMCs and somites of transgenic mice. Finally, we have shown that a
multimerized copy of SME-4 (bp -190 to -110) when linked to the minimal
SM22alpha promoter (bp -90 to +41) is necessary and sufficient to direct
high-level transcription in an SMC lineage-restricted fashion. Taken
together, these data demonstrate that distinct transcriptional regulatory
programs control SM22alpha gene expression in arterial versus visceral
SMCs. Moreover, these data are consistent with a model in which
combinatorial interactions between SRF and other transcription factors that
bind to SME-4 (and that bind directly to SRF) activate transcription of the
SM22alpha gene in arterial SMCs.
Copyright © 1997, American Society for Microbiology
A serum response factor-dependent transcriptional regulatory program identifies distinct smooth muscle cell sublineages
Department of Medicine, University of Chicago, Illinois 60637, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»