Hepatocyte growth factor signaling ameliorates podocyte injury and proteinuria.
Hepatocyte growth factor (HGF) is a potent antifibrotic protein that inhibits kidney fibrosis through several mechanisms. To study its role in podocyte homeostasis, injury, and repair in vivo, we generated conditional knockout mice in which the HGF receptor, c-met, was specifically deleted in podocytes using the Cre-LoxP system. Mice with podocyte-specific ablation of c-met (podo-met(-/-)) developed normally. No albuminuria or overt pathologic lesions were detected up to 6 months of age, suggesting that HGF signaling is dispensable for podocyte maturation, survival, and function under normal physiologic conditions. However, after adriamycin treatment, podo-met(-/-) mice developed more severe podocyte injury and albuminuria than their control littermates. Ablation of c-met also resulted in more profound suppression of Wilms tumor 1 (WT1) and nephrin expression, and podocyte apoptosis after injury. When HGF was expressed ectopically in vivo, it ameliorated adriamycin-induced albuminuria, preserved WT1 and nephrin expression, and inhibited podocyte apoptosis. However, exogenous HGF failed to significantly reduce albuminuria in podo-met(-/-) mice, suggesting that podocyte-specific c-met activation by HGF confers renal protection. In vitro, HGF was able to preserve WT1 and nephrin expression in cultured podocytes after adriamycin treatment. HGF also protected podocytes from apoptosis induced by a lethal dose of adriamycin primarily through a phosphoinositide 3-kinase (PI3K)/Akt-dependent pathway. Collectively, these results indicate that HGF/c-met signaling has an important role in protecting podocytes from injury, thereby reducing proteinuria.
Dai
Chunsun
C
Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Saleem
Moin A
MA
Holzman
Lawrence B
LB
Mathieson
Peter
P
Liu
Youhua
Y
D000367:Age Factors; D000419:Albuminuria / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D019610:Cytoprotection; D004195:Disease Models, Animal; D004317:Doxorubicin; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D007674:Kidney Diseases / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D050199:Podocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met / Q000172:deficiency / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors; D025721:WT1 Proteins / Q000378:metabolism
D008565:Membrane Proteins; D025721:WT1 Proteins; C113267:nephrin; D017228:Hepatocyte Growth Factor; D004317:Doxorubicin; D019869:Phosphatidylinositol 3-Kinases; D019859:Proto-Oncogene Proteins c-met; D051057:Proto-Oncogene Proteins c-akt