Tan NY, Midgley VC, Kavurma MM, Santiago FS, Luo X, Peden R, Fahmy RG, Berndt MC, Molloy MP, Khachigian LM. Angiotensin II-inducible platelet-derived growth factor-D transcription requires specific Ser/Thr residues in the second zinc finger region of Sp1.
Circ Res 2008;
102:e38-51. [PMID:
18258854 DOI:
10.1161/circresaha.107.167395]
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Abstract
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.
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