title: Met activation is required for early cytoprotection after ischemic kidney injury.
abstract: Renal proximal tubule epithelial cells express high levels of the hepatocyte growth factor receptor Met, and both the receptor and ligand are upregulated after ischemic injury. Activation of the Met receptor after hepatocyte growth factor stimulation in vitro promotes activities involved in kidney repair, including cell survival, migration, and proliferation. However, characterizing the in vivo role of these signaling events in proximal tubule responses to kidney injury has been difficult because global Met knockout results in embryonic lethality due to placental and liver abnormalities. Here, we used γGT-Cre to knockout Met receptor expression selectively in the proximal tubules of mice (γGT-Cre;Met(fl/fl)). The kidneys of these mice developed normally, but exhibited increased initial tubular injury, tubular cell apoptosis, and serum creatinine after ischemia/reperfusion compared with γGT-Cre;Met(+/+) kidneys. These changes in γGT-Cre;Met(fl/fl) mice correlated with a selective reduction in PI3K/Akt activation in response to injury and subsequent decreases in inhibitory phosphorylation of the proapoptotic factor Bad and activating phosphorylation of the ribosomal regulatory protein p70-S6 kinase. Moreover, tubular cell proliferation after ischemia/reperfusion was delayed in γGT-Cre;Met(fl/fl) mice. In conclusion, this study identifies Met-dependent phosphoinositide 3-kinase activation in proximal tubules as a critical determinant of initial tubular cell survival and reparative proliferation after ischemic injury.
authors.affiliation: Section of Nephrology, Department of Pediatrics.
authors.forename: Sherene
authors.initials: S
authors.lastname: Mason
authors.forename: Carlos
authors.initials: C
authors.lastname: Hader
authors.forename: Arnaud
authors.initials: A
authors.lastname: Marlier
authors.forename: Gilbert
authors.initials: G
authors.lastname: Moeckel
authors.forename: Lloyd G
authors.initials: LG
authors.lastname: Cantley
mesh_terms: D058186:Acute Kidney Injury / Q000201:enzymology*; D000818:Animals; D017209:Apoptosis; D055785:Gene Knockdown Techniques; D007668:Kidney / Q000098:blood supply* / Q000201:enzymology; D007687:Kidney Tubules, Proximal / Q000201:enzymology / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009928:Organ Specificity; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000502:physiology*; D015427:Reperfusion Injury / Q000201:enzymology*; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D051025:bcl-Associated Death Protein / Q000378:metabolism
chemical_list: C494820:Bad protein, mouse; D051025:bcl-Associated Death Protein; D019869:Phosphatidylinositol 3-Kinases; C080835:RON protein; D020794:Receptor Protein-Tyrosine Kinases; C514862:Akt1 protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa