Elements of the smooth muscle alpha-actin promoter required in cis for transcriptional activation in smooth muscle. Evidence for cell type-specific regulation.
To assess the role of cis-acting elements within the smooth muscle alpha-actin gene in smooth muscle cells (SMC), we transfected chicken smooth muscle alpha-actin promoter-chloramphenicol acetyltransferase gene fusion plasmids into SMC derived from rat and chicken aortas. In marked contrast to effects in chicken skeletal myoblasts and fibroblasts, p122CAT (positions -122 to +19), containing two conserved CArG elements, elicited a modest increase in chloramphenicol acetyltransferase reporter activity in chicken SMC. Addition of upstream sequences between -122 and -151 (p151CAT) increased activity in adult chicken SMC. Addition of sequence between positions -151 and -257 (p257CAT) resulted in a 7-fold increase in chloramphenicol acetyltransferase activity over that of p151CAT in rat SMC, but not in chicken SMC. A genomic clone encoding the rat smooth muscle alpha-actin gene was isolated, and the 5'-flanking region was partially characterized. Comparison of primary sequence between rat and chicken promoters showed a conserved E box motif at position -214 in the chicken gene and at position -213 in the rat gene. Results of these studies demonstrate that regions upstream of the conserved CArG elements exert potent regulatory effects on transcription and that SMC require different cis-acting elements than other cell types to transcriptionally regulate this gene.
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Department of Physiology, University of Virginia School of Medicine, Charlottesville 22908.
McQuinn
T C
TC
Yin
K C
KC
Thompson
M M
MM
Takeyasu
K
K
Schwartz
R J
RJ
Owens
G K
GK
D000199:Actins / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002478:Cells, Cultured; D002645:Chickens; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D002872:Chromosome Deletion; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D015870:Gene Expression; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000378:metabolism*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D051381:Rats; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D015533:Transcriptional Activation
D000199:Actins; D015500:Chloramphenicol O-Acetyltransferase