Regulation of cyclin D(1) expression and DNA synthesis by phosphatidylinositol 3-kinase in airway smooth muscle cells.
We have shown in bovine tracheal myocytes that extracellular signal-regulated kinase (ERK) and Rac1 function as upstream activators of transcription from the cyclin D(1) promoter. We now examine the role of phosphatidylinositol (PI) 3-kinase in this process. PI 3-kinase activity was increased by platelet-derived growth factor (PDGF) and attenuated by the PI 3-kinase inhibitors wortmannin and LY294002. These inhibitors also decreased cyclin D(1) promoter activity, protein abundance, and DNA synthesis. Overexpression of the active catalytic subunit of PI 3-kinase (p110(PI) (3-K)CAAX) was sufficient to activate the cyclin D(1) promoter. Wortmannin and LY294002 failed to attenuate PDGF-induced ERK activation, and overexpression of p110(PI) (3-K)CAAX was insufficient to activate ERK. p110(PI) (3-K)CAAX-induced cyclin D(1) promoter activity was not blocked by PD98059, an inhibitor of mitogen-activated protein kinase/ERK kinase. We next examined whether PI 3-kinase and the 21-kD guanidine triphosphatase Rac1 regulate cyclin D(1) promoter activity by similar mechanisms. p110(PI) (3-K)CAAX-induced cyclin D(1) promoter activity was decreased by two inhibitors of Rac1-mediated signaling, catalase and diphenylene iodonium. Further, PDGF, PI 3-kinase, and Rac1 each activated the cyclin D(1) promoter at the cyclic adenosine monophosphate response element binding protein (CREB)/activating transcription factor (ATF)-2 binding site, as evidenced by expression of a CREB/ATF-2 reporter plasmid. Finally, PI 3-kinase and Rac1-induced CREB/ATF-2 transactivation were each inhibited by catalase. Together, these data suggest that in airway smooth muscle (ASM) cells, PI 3-kinase regulates transcription from the cyclin D(1) promoter and DNA synthesis in an ERK-independent manner. Further, PI 3-kinase and Rac1 regulate ASM cell cycle traversal via a common cis-regulatory element in the cyclin D(1) promoter.
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Department of Pediatrics, University of Chicago, Chicago, Illinois, USA.
Li
J
J
Wang
Y
Y
Kartha
S
S
Pestell
R G
RG
Hershenson
M B
MB
D051698:Activating Transcription Factor 2; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001665:Binding Sites; D002417:Cattle; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D009130:Muscle, Smooth / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D014132:Trachea / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D051698:Activating Transcription Factor 2; D000975:Antioxidants; D017362:Cyclic AMP Response Element-Binding Protein; D010982:Platelet-Derived Growth Factor; D014157:Transcription Factors; D019938:Cyclin D1; D019869:Phosphatidylinositol 3-Kinases