Increased Sp1 phosphorylation as a mechanism of hepatocyte growth factor (HGF/SF)-induced vascular endothelial growth factor (VEGF/VPF) transcription.
Hepatocyte growth factor (HGF/SF)-induced expression of vascular endothelial growth factor (VEGF/VPF) has been implicated in paracrine amplification of angiogenesis, contributing to angiogenic responses during inflammation, wound healing, collateral formation and tumor growth. We have shown previously that HGF/SF-mediated VEGF/VPF expression by keratinocytes is primarily dependent on transcriptional activation, and we mapped the HGF/SF-responsive element to a GC-rich region between bp -88 and -65. Sp1-like factors bind to this element constitutively; however the VEGF/VPF promoter is transactivated by HGF/SF in the absence of induced binding activity. In experimental approaches to clarify molecular mechanisms of Sp1-dependent VEGF/VPF gene transcription, neither HGF/SF-dependent changes in nuclear expression nor in relative DNA binding activity of Sp family members to the indicated element were observed. Thus, HGF/SF was hypothesized to induce VEGF/VPF gene transcription via increased transactivation activity of Sp1 owing to biochemical modification. In immunoprecipitation studies, HGF/SF was found to increase the amount of serine-phosphorylated Sp1, revealing a likely mechanism of HGF/SF-induced VEGF/VPF expression, as phosphorylation may enhance the transcriptional activity of Sp1. The contribution of different signaling molecules to HGF/SF-induced VEGF/VPF transcription was demonstrated by the use of chemical inhibition, of expression of kinase-deficient signaling proteins, and by the use of antisense oligonucleotides. Herein, we provide evidence that PI 3-kinase, MEK1/2 and PKC-zeta play a significant role in HGF/SF-induced VEGF/VPF promoter activation. Together, our results elucidate a critical pathway of paracrine amplification of angiogenesis, suggesting that HGF/SF-induced Sp1 phosphorylation may activate VEGF/VPF promoter activity that requires the contribution of distinct signaling molecules.
Reisinger
Kerstin
K
Department of Dermatology, Klinikum der J. W. Goethe-Universität, Frankfurt am Main, Germany.
Kaufmann
Roland
R
Gille
Jens
J
D000818:Animals; D002460:Cell Line; D016228:Endothelial Growth Factors / Q000378:metabolism*; D005057:Eukaryotic Cells / Q000378:metabolism*; D005809:Genes, Regulator / Q000235:genetics; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008222:Lymphokines / Q000378:metabolism*; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000378:metabolism* / Q000503:physiopathology; D018919:Neovascularization, Physiologic / Q000502:physiology*; D019899:Paracrine Communication / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D015533:Transcriptional Activation / Q000235:genetics; D015854:Up-Regulation / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000099221:Protein Kinase C zeta
D016228:Endothelial Growth Factors; D017228:Hepatocyte Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D016329:Sp1 Transcription Factor; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000099221:Protein Kinase C zeta; C482125:MAP2K1 protein, human