PDGF induction of alpha 2 integrin gene expression is mediated by protein kinase C-zeta.
Platelet-derived growth factor (PDGF) stimulates fibroblasts to move over collagen and contract three-dimensional collagen gels, processes important in wound repair and fibrocontractive diseases. These processes depend on alpha 2 beta 1 integrin ligation of collagen and PDGF induces the expression of this integrin. Several lines of evidence presented here suggest that PKC-zeta plays a role in alpha 2 integrin gene expression. The induction was blocked by chemical inhibitors for protein tyrosine kinases (PTK), genistein, and protein kinase C (PKC), chelerythrine, and bisindolylmaleimide GF 109203X. Cells depleted of phorbol 12-myristate 13-acetate (PMA)-inducible PKCs by chronic treatment with PMA still demonstrated an alpha 2 response to PDGF indicating that a non-PMA-sensitive PKC isoform was required. PDGF induced kinase activity in PKC-zeta immunoprecipitates. Antisense oligonucleotides complementary to 5' end of PKC-zeta mRNA sequences blocked the PDGF-induced increase of alpha 2 mRNA levels up to 70%, indicating PKC-zeta, a non-PMA-sensitive PKC isoform, is a component of the PDGF stimulatory pathway for alpha 2 mRNA synthesis. A 961-base pair (bp) upstream region of alpha 2 gene/CAT construct transfected into human dermal fibroblasts was positively regulated by PDGF as judged by CAT enzymatic levels. Both PTK and PKC inhibitors blocked PDGF-stimulation of the alpha 2 promoter fragment/CAT construct, indicating that the phosphorylation requirement occurred at alpha 2 promoter-directed transcription level. Therefore, we propose that PDGF-stimulatory pathway of alpha 2 integrin gene expression involves multiple cellular protein kinases, one of which is PKC-zeta.
Xu
J
J
Department of Dermatology, School of Medicine, SUNY at Stony Brook 11794-8165, USA.
Zutter
M M
MM
Santoro
S A
SA
Clark
R A
RA
D000328:Adult; D015703:Antigens, CD / Q000235:genetics*; D001483:Base Sequence; D002478:Cells, Cultured; D015536:Down-Regulation; D004789:Enzyme Activation; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D039421:Integrin alpha2; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000502:physiology*; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic; D000099221:Protein Kinase C zeta
D015703:Antigens, CD; D039421:Integrin alpha2; D016376:Oligonucleotides, Antisense; D010982:Platelet-Derived Growth Factor; D011493:Protein Kinase C; D011505:Protein-Tyrosine Kinases; D012333:RNA, Messenger; D013755:Tetradecanoylphorbol Acetate; D000099221:Protein Kinase C zeta