Angiotensin II-inducible platelet-derived growth factor-D transcription requires specific Ser/Thr residues in the second zinc finger region of Sp1.
Sp1, the first identified and cloned transcription factor, regulates gene expression via multiple mechanisms including direct protein-DNA interactions, protein-protein interactions, chromatin remodeling, and maintenance of methylation-free CpG islands. Sp1 is itself regulated at different levels, for example, by glycosylation, acetylation, and phosphorylation by kinases such as the atypical protein kinase C-zeta. Although Sp1 controls the basal and inducible regulation of many genes, the posttranslational processes regulating its function and their relevance to pathology are not well understood. Here we have used a variety of approaches to identify 3 amino acids (Thr668, Ser670, and Thr681) in the zinc finger domain of Sp1 that are modified by PKC-zeta and have generated novel anti-peptide antibodies recognizing the PKC-zeta-phosphorylated form of Sp1. Angiotensin II, which activates PKC-zeta phosphorylation (at Thr410) via the angiotensin II type 1 receptor, stimulates Sp1 phosphorylation and increases Sp1 binding to the platelet-derived growth factor-D promoter. All 3 residues in Sp1 (Thr668, Ser670, and Thr681) are required for Sp1-dependent platelet-derived growth factor-D activation in response to angiotensin II. Immunohistochemical analysis revealed that phosphorylated Sp1 is expressed in smooth muscle cells of human atherosclerotic plaques and is dynamically expressed together with platelet-derived growth factor-D in smooth muscle cells of the injured rat carotid artery wall. This study provides new insights into the regulatory mechanisms controlling the PKC-zeta-phospho-Sp1 axis and angiotensin II-inducible gene expression.
Tan
Nicole Y
NY
Centre for Vascular Research, School of Medical Sciences, University of New South Wales, Sydney, Australia.
Midgley
Valerie C
VC
Kavurma
Mary M
MM
Santiago
Fernando S
FS
Luo
Xiao
X
Peden
Ryan
R
Fahmy
Roger G
RG
Berndt
Michael C
MC
Molloy
Mark P
MP
Khachigian
Levon M
LM
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002340:Carotid Artery Diseases / Q000378:metabolism / Q000503:physiopathology*; D002404:Catheterization / Q000009:adverse effects; D002478:Cells, Cultured; D004195:Disease Models, Animal; D006801:Humans; D008222:Lymphokines / Q000235:genetics*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016296:Mutagenesis; D010766:Phosphorylation / Q000187:drug effects; D010982:Platelet-Derived Growth Factor / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000378:metabolism; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D012694:Serine / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D013912:Threonine / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D016335:Zinc Fingers / Q000502:physiology; D000099221:Protein Kinase C zeta
D000804:Angiotensin II; D000906:Antibodies; D008222:Lymphokines; D010982:Platelet-Derived Growth Factor; D011493:Protein Kinase C; D012694:Serine; D016329:Sp1 Transcription Factor; D013912:Threonine; D014662:Vasoconstrictor Agents; D000099221:Protein Kinase C zeta; C427493:PDGFD protein, human; C498952:Pdgfd protein, rat