title: Galpha13 regulates MEF2-dependent gene transcription in endothelial cells: role in angiogenesis.
abstract: The alpha subunit of heterotrimeric G13 protein is required for the embryonic angiogenesis (Offermanns et al., Science 275:533-536, 1997). However, the molecular mechanism of Galpha13-dependent angiogenesis is not understood. Here, we show that myocyte-specific enhancer factor-2 (MEF2) mediates Galpha13-dependent angiogenesis. Our data showed that constitutively activated Galpha13Q226L stimulated MEF2-dependent gene transcription. In addition, downregulation of endogenous Galpha13 inhibited thrombin-stimulated MEF2-dependent gene transcription in endothelial cells. Both Ca(2+)/calmodulin-dependent kinase IV (CaMKIV) and histone deacetylase 5 (HDAC5) were involved in Galpha13-mediated MEF2-dependent gene transcription. Galpha13Q226L also increased Ca(2+)/calmodulin-independent CaMKIV activity, while dominant negative mutant of CaMKIV inhibited MEF2-dependent gene transcription induced by Galpha13Q226L. Furthermore, Galpha13Q226L was able to derepress HDAC5-mediated repression of gene transcription and induce the translocation of HDAC5 from nucleus to cytoplasm. Finally, downregulation of endogenous Galpha13 and MEF2 proteins in endothelial cells reduced cell proliferation and capillary tube formation. Decrease of endothelial cell proliferation that was caused by the Galpha13 downregulation was partially restored by the constitutively active MEF2-VP16. Our studies suggest that MEF2 proteins are an important component in Galpha13-mediated angiogenesis.
authors.affiliation: Department of Pharmacology, University of Illinois, 835 S. Wolcott Ave., Chicago, IL 60612, USA.
authors.forename: Guoquan
authors.initials: G
authors.lastname: Liu
authors.forename: Jingyan
authors.initials: J
authors.lastname: Han
authors.forename: Jasmina
authors.initials: J
authors.lastname: Profirovic
authors.forename: Elena
authors.initials: E
authors.lastname: Strekalova
authors.forename: Tatyana A
authors.initials: TA
authors.lastname: Voyno-Yasenetskaya
mesh_terms: D000818:Animals; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D044365:GTP-Binding Protein alpha Subunits, G12-G13 / Q000378:metabolism*; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D064326:MEF2 Transcription Factors; D051379:Mice; D050505:Mutant Proteins / Q000378:metabolism; D018006:Myogenic Regulatory Factors / Q000378:metabolism*; D041681:NIH 3T3 Cells; D018919:Neovascularization, Physiologic / Q000187:drug effects; D054648:Protein Phosphatase 2 / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D012097:Repressor Proteins / Q000378:metabolism; D013917:Thrombin / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D064326:MEF2 Transcription Factors; D050505:Mutant Proteins; D018006:Myogenic Regulatory Factors; D012097:Repressor Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D054648:Protein Phosphatase 2; D013917:Thrombin; C404500:HDAC5 protein, human; D006655:Histone Deacetylases; D044365:GTP-Binding Protein alpha Subunits, G12-G13