title: Transforming growth factor-beta1 stimulates vascular endothelial growth factor 164 via mitogen-activated protein kinase kinase 3-p38alpha and p38delta mitogen-activated protein kinase-dependent pathway in murine mesangial cells.
abstract: Transforming growth factor-beta1 (TGF-beta1) is a potent inducer of extracellular matrix synthesis leading to progressive glomerular fibrosis. The intracellular signaling mechanisms involved in this process remain incompletely understood. The p38 mitogen-activated protein kinase (MAPK) is a major stress signal transducing pathway that is rapidly activated by TGF-beta1 in mesangial cells. We have previously demonstrated MKK3 as the immediate upstream MAPK kinase required for selective activation of p38 MAPK isoforms, p38alpha and p38delta, and stimulation of pro-alpha1(I) collagen by TGF-beta1 in murine mesangial cells. In this study, we further sought to determine MAPK kinase 3 (MKK3)-dependent TGF-beta1 responses by gene expression profiling analysis utilizing mesangial cells isolated from Mkk3-/- mice compared with Mkk3+/+ controls. Interestingly, vascular endothelial growth factor (VEGF) was identified as a TGF-beta1-induced gene affected by deletion of Mkk3. VEGF is a well known endothelial mitogen, whose actions in nonendothelial cell types are still not well understood. We confirmed that TGF-beta1 increased VEGF mRNA and protein synthesis of VEGF164 and VEGF188 isoforms in wild-type mesangial cells. However, in the Mkk3-/- mesangial cells, both TGF-beta1-induced VEGF mRNA and VEGF164 protein expression were inhibited, whereas TGF-beta1-induced VEGF188 protein expression was unaffected. Furthermore, transfection of dominant negative mutants of p38alpha and p38delta resulted in marked inhibition of TGF-beta1-induced VEGF164 expression but not VEGF188, and treatment with recombinant mouse VEGF164 increased collagen and fibronectin mRNA expression in mesangial cells. Taken together, our findings suggest a critical role for the MKK3-p38alpha and p38delta MAPK pathway in mediating VEGF164 isoform-specific stimulation by TGF-beta1 in mesangial cells. Further, VEGF164 stimulates collagen and fibronectin expression in mesangial cells and thus in turn enhances TGF-beta1-induced extracellular matrix and may play an important role in progressive glomerular fibrosis.
authors.affiliation: Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Joon Hyeok
authors.initials: JH
authors.lastname: Kwak
authors.forename: Sung Il
authors.initials: SI
authors.lastname: Kim
authors.forename: Yanjuan
authors.initials: Y
authors.lastname: He
authors.forename: Mary E
authors.initials: ME
authors.lastname: Choi
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003094:Collagen / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D005353:Fibronectins / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D020869:Gene Expression Profiling; D005920:Glomerular Mesangium / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D048371:MAP Kinase Kinase 3; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D048292:Mitogen-Activated Protein Kinase 13; D048308:Mitogen-Activated Protein Kinase 14; D020929:Mitogen-Activated Protein Kinase Kinases / Q000172:deficiency / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009154:Mutation; D020033:Protein Isoforms / Q000032:analysis; D011505:Protein-Tyrosine Kinases / Q000172:deficiency / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D011994:Recombinant Proteins; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D005353:Fibronectins; D020033:Protein Isoforms; D012333:RNA, Messenger; D011994:Recombinant Proteins; C508960:TGFB1 protein, human; C508961:Tgfb1 protein, mouse; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A; D003094:Collagen; D048292:Mitogen-Activated Protein Kinase 13; D011505:Protein-Tyrosine Kinases; D048308:Mitogen-Activated Protein Kinase 14; D020928:Mitogen-Activated Protein Kinases; D048371:MAP Kinase Kinase 3; C482530:MAP2K3 protein, human; C482531:Map2k3 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases