title: Klotho protein diminishes endothelial apoptosis and senescence via a mitogen-activated kinase pathway.
abstract: OBJECTIVE
  Mice that carry the Klotho mutation (KL(-) (/) (-) ) manifest diverse age-related disorders similar to those observed in humans. Thus, the Klotho protein might function as an anti-aging hormone in mammals. Recently, we reported that Klotho recombinant protein attenuated apoptosis and cellular senescence in endothelial cells, but the mechanism remained unclear. Here, we designed an in vitro study to test whether inhibitors of extracellular signal-regulated kinase and mitogen-activated kinase kinase could affect Klotho regulation of apoptosis and cellular senescence.
  
  
  METHODS
  Cellular senescence was investigated in human umbilical vein endothelial cells treated with or without Klotho recombinant protein, and with or without inhibitors of mitogen-activated kinases. Senescence was quantified by staining with senescence-associated β-galactosidase and by evaluating western blots probed for phosphorylation of mitogen-activated kinases. Apoptosis was assayed on western probed for p53, p21, and caspase-3 and -9.
  
  
  RESULTS
  The Klotho recombinant protein induced transient phosphorylation of mitogen-activated kinases within a few minutes. Application of inhibitors of mitogen-activated kinases attenuated the ability of Klotho to interfere with apoptosis and senescence in endothelial cells.
  
  
  CONCLUSIONS
  This study demonstrated that Klotho attenuated cellular apoptosis and senescence in vascular cells via mitogen-activated kinase kinase and extracellular signal-regulated kinase pathways.
authors.affiliation: Department of Geriatric Medicine, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Maekawa
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Ohishi
authors.forename: Masashi
authors.initials: M
authors.lastname: Ikushima
authors.forename: Koichi
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Osamu
authors.initials: O
authors.lastname: Yasuda
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Oguro
authors.forename: Hiroko
authors.initials: H
authors.lastname: Yamamoto-Hanasaki
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tatara
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Takeya
authors.forename: Hiromi
authors.initials: H
authors.lastname: Rakugi
mesh_terms: D000704:Analysis of Variance; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects*; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology*; D005966:Glucuronidase / Q000494:pharmacology*; D006801:Humans; D000090265:Klotho Proteins; D010766:Phosphorylation; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014471:Umbilical Veins / Q000166:cytology; D001616:beta-Galactosidase / Q000378:metabolism; D054462:p21-Activated Kinases / Q000378:metabolism
chemical_list: D016159:Tumor Suppressor Protein p53; D054462:p21-Activated Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D001616:beta-Galactosidase; D005966:Glucuronidase; D000090265:Klotho Proteins; D020169:Caspases