Sp1 phosphorylation regulates inducible expression of platelet-derived growth factor B-chain gene via atypical protein kinase C-zeta

• Published in: Nucleic acids research Vol. 29; no. 5; pp. 1027 - 1033
• Main Authors: Rafty, L A, Khachigian, L M
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.03.2001
• Subjects: Animals; anthracyclines; Binding Sites; Cells, Cultured; Chloramphenicol O-Acetyltransferase - drug effects; Chloramphenicol O-Acetyltransferase - genetics; Chloramphenicol O-Acetyltransferase - metabolism; DNA - genetics; DNA - metabolism; Egr-1 protein; Gene Expression Regulation - drug effects; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; nogalamycin; Nogalamycin - pharmacology; Oligonucleotides - genetics; Oligonucleotides - metabolism; Phosphorylation - drug effects; Platelet-Derived Growth Factor - genetics; Promoter Regions, Genetic - genetics; Protein Binding - drug effects; Protein Kinase C - metabolism; Rats; Rats, Inbred WKY; Recombinant Fusion Proteins - drug effects; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; RNA, Messenger - drug effects; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sp1 Transcription Factor - metabolism; Time Factors; Zinc Fingers - genetics
• DOI: 10.1093/nar/29.5.1027
• ISSN: 1362-4962; 0305-1048

Platelet-derived growth factor (PDGF) is a broadly expressed mitogenic and chemotactic factor with diverse roles in a number of physiologic and pathologic settings. The zinc finger transcription factors Sp1, Sp3 and Egr-1 bind to overlapping elements in the proximal PDGF B-chain promoter and activate transcription of this gene. The anthracycline nogalamycin has previously been reported to inhibit the capacity of Egr-1 to bind DNA in vitro. Here we used electrophoretic mobility shift assays to show that nogalamycin added to cells in culture did not alter the interaction of Egr-1 with the PDGF-B promoter. Instead, it enhanced the capacity of Sp1 to bind DNA. Nogalamycin increased PDGF-B mRNA expression at the level of transcription, which was abrogated by mutation of the Sp1 binding site in the PDGF-B promoter or overexpression of mutant Sp1. Rather than increasing total levels of Sp1, nogalamycin altered the phosphorylation state of the transcription factor. Overexpression of dominant-negative PKC-zeta blocked nogalamycin-inducible Sp1 phosphorylation and PDGF-B promoter-dependent expression. Nogalamycin stimulated the phosphorylation of PKC-zeta (on residue Thr(410)). These findings demonstrate for the first time that PKC-zeta and Sp1 phosphorylation mediate the inducible expression of this growth factor.