Regulation of the SM-20 prolyl hydroxylase gene in smooth muscle cells.
SM-20 encodes an intracellular prolyl hydroxylase that acts on hypoxia inducible factor (HIF)-1alpha, targeting it for proteasomal degradation. By decreasing HIF-alpha, SM-20 is thought to modulate the expression of hypoxia-regulated genes. SM-20 expression in the arterial wall is restricted to smooth muscle cells, which play a critical role in atherosclerosis and arterial injury. To further elucidate the regulation of SM-20 in smooth muscle, we cloned and analyzed the rat SM-20 promoter. In transient transfections, the SM-20 promoter displayed approximately 6-fold greater activity in smooth muscle cells vs. fibroblasts. Deletion analysis and electrophoretic mobility shift assays demonstrated that SM-20 transcription was regulated by two Sp1/Sp3 sites. A shift in binding to the Sp1/Sp3 sites, a decrease in Sp1 and Sp3 protein levels, and the emergence of a lower molecular weight form of Sp1 were seen in serum-deprived or post-confluent SMC, suggesting that SM-20 is regulated during smooth muscle cell differentiation.
Menzies
Keon
K
The Zena and Michael A. Wiener Cardiovascular Institute, Department of Medicine, The Mount Sinai School of Medicine, New York, NY 10029, USA.
Liu
Bin
B
Kim
William J H
WJ
Moschella
Maria C
MC
Taubman
Mark B
MB
D000818:Animals; D001483:Base Sequence; D004247:DNA; D024202:Electrophoretic Mobility Shift Assay; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D009154:Mutation; D011393:Procollagen-Proline Dioxygenase / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051381:Rats; D017207:Rats, Sprague-Dawley
D004247:DNA; D011393:Procollagen-Proline Dioxygenase