Upstream stimulatory factor 1 regulates osteopontin expression in smooth muscle cells.
Vascular smooth muscle cells (SMCs) undergo a dramatic phenotypic transition in response to injury and ex vivo culture that includes enhanced proliferation, migration, matrix deposition, and alterations in gene expression. Osteopontin is a good marker for the injury-induced SMC phenotypic state in vivo and in vitro. To identify transcription factors that might control the regulation of osteopontin expression, we investigated cultured vascular SMCs that express high and low levels of osteopontin. Using nuclear run-on assays, mRNA stability studies, and deletion analysis, we demonstrate that regulation of osteopontin steady-state mRNA levels in SMCs occurs at the transcriptional level. Transient transfection and gel-shift analyses of osteopontin promoter indicated that a region between -123 and +66 was involved in the expression of osteopontin. Supershift EMSAs identified the bHLH-leucine zipper transcription factor upstream stimulatory factor-1 (USF1) as the protein binding to this sequence. Finally, we show that USF1 protein is induced in vivo within 24 h of balloon angioplasty of rat carotids coordinately with osteopontin induction. These data suggest that USF1 governs expression of osteopontin in cultured vascular SMCs and might contribute to initial osteopontin expression observed post carotid injury and in vascular pathologies in vivo.
Department of Pathology, University of Washington, Seattle, Washington, 98195, USA.
U M
UM
Malyankar
R
R
Hanson
S M
SM
Schwartz
A L
AL
Ridall
C M
CM
Giachelli
D000375:Aging; D000800:Angioplasty, Balloon; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D002339:Carotid Arteries / Q000378:metabolism; D020212:Carotid Artery Injuries; D002478:Cells, Cultured; D016384:Consensus Sequence / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D009154:Mutation; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism; D053495:Osteopontin; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020218:Response Elements / Q000235:genetics; D012795:Sialoglycoproteins / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D014162:Transfection; D051720:Upstream Stimulatory Factors
D004268:DNA-Binding Proteins; D009841:Oligonucleotides; D012333:RNA, Messenger; D012795:Sialoglycoproteins; C506897:Spp1 protein, rat; D014157:Transcription Factors; D051720:Upstream Stimulatory Factors; C497182:Usf1 protein, rat; D053495:Osteopontin