Blank RS

Granot Y

Johnson EM

Kim JH

Kocher 0

Moss JB

Owens GK

Rao GN

Vasoconstrictors such as arginine vasopressin (AVP) and angiotensin II (Ang II) have been shown to increase protein and mRNA levels of smooth muscle alpha-actin (SM-alpha-actin) in vascular smooth muscle cells. In the same cells, platelet-derived growth factor (PDGF) decreased SM-alpha-actin protein and mRNA. The rat SM-alpha-actin promoter that has recently been isolated contains two E-boxes and three CC(A/T)6GG (CArG) elements. To examine regulation of the SM-alpha-actin promoter, a 765-bp region of the rat SM-alpha-actin gene was ligated into chloramphenicol acetyltransferase (CAT)-containing vectors and transfected into rat aortic vascular smooth muscle cells. Stimulation of cells with either AVP or Ang II increased CAT activity 5- to 10-fold. PDGF was able to completely block the AVP-induced increase in CAT activity. To identify regions of the promoter responsible for both the AVP stimulation and PDGF inhibition of promoter activity, a series of truncation mutants were prepared and transfected into vascular smooth muscle cells. Truncation of both E-boxes and the most distal CArG element did not qualitatively alter either AVP-induced stimulation of CAT activity or PDGF inhibition. However, removal of the middle CArG element resulted in a loss of AVP stimulation. These studies indicate that the AVP-induced elevation and PDGF-induced inhibition of SM-alpha-actin levels in vascular smooth muscle cells are mediated at least in part through regulation of the SM-alpha-actin promoter. The critical region of the promoter mediating this effect involves at a minimum one of the CArG elements.</jats:p

V Van Putten

X Li

J Maselli

R A Nemenoff

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Circulation Research

Regulation of smooth muscle alpha-actin promoter by vasopressin and platelet-derived growth factor in rat aortic vascular smooth muscle cells.

Regulation of smooth muscle alpha-actin promoter by vasopressin and platelet-derived growth factor in rat aortic vascular smooth muscle cells.

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