title: mTORC2 Signaling Regulates Nox4-Induced Podocyte Depletion in Diabetes.
abstract: Podocyte apoptosis is a critical mechanism for excessive loss of urinary albumin that eventuates in kidney fibrosis. Oxidative stress plays a critical role in hyperglycemia-induced glomerular injury. We explored the hypothesis that mammalian target of rapamycin complex 2 (mTORC2) mediates podocyte injury in diabetes.
  
  
  
  High glucose (HG)-induced podocyte injury reflected by alterations in the slit diaphragm protein podocin and podocyte depletion/apoptosis. This was paralleled by activation of the Rictor/mTORC2/Akt pathway. HG also increased the levels of Nox4 and NADPH oxidase activity. Inhibition of mTORC2 using small interfering RNA (siRNA)-targeting Rictor in vitro decreased HG-induced Nox1 and Nox4, NADPH oxidase activity, restored podocin levels, and reduced podocyte depletion/apoptosis. Inhibition of mTORC2 had no effect on mammalian target of rapamycin complex 1 (mTORC1) activation, described by our group to be increased in diabetes, suggesting that the mTORC2 activation by HG could mediate podocyte injury independently of mTORC1. In isolated glomeruli of OVE26 mice, there was a similar activation of the Rictor/mTORC2/Akt signaling pathway with increase in Nox4 and NADPH oxidase activity. Inhibition of mTORC2 using antisense oligonucleotides targeting Rictor restored podocin levels, reduced podocyte depletion/apoptosis, and attenuated glomerular injury and albuminuria.
  
  
  
  Our data provide evidence for a novel function of mTORC2 in NADPH oxidase-derived reactive oxygen species generation and podocyte apoptosis that contributes to urinary albumin excretion in type 1 diabetes.
  
  
  
  mTORC2 and/or NADPH oxidase inhibition may represent a therapeutic modality for diabetic kidney disease. Antioxid. Redox Signal. 25, 703-719.
authors.affiliation: 1 Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut , Beirut, Lebanon .|2 UMR-S 1124 INSERM, Paris Descartes University, Sorbonne Paris Cite University , Centre Interdisciplinaire Chimie Biology, Paris, France .
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Eid
authors.affiliation: 1 Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut , Beirut, Lebanon .
authors.forename: Suzan
authors.initials: S
authors.lastname: Boutary
authors.affiliation: 1 Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut , Beirut, Lebanon .
authors.forename: Kawthar
authors.initials: K
authors.lastname: Braych
authors.affiliation: 3 Department of Pharmacology and Toxicology, Faculty of Medicine and Medical Center, American University of Beirut , Beirut, Lebanon .
authors.forename: Ramzi
authors.initials: R
authors.lastname: Sabra
authors.affiliation: 2 UMR-S 1124 INSERM, Paris Descartes University, Sorbonne Paris Cite University , Centre Interdisciplinaire Chimie Biology, Paris, France .
authors.forename: Charbel
authors.initials: C
authors.lastname: Massaad
authors.affiliation: 4 Department of Nephrology, Hamad Medical Corporation , Doha, Qatar .
authors.forename: Ahmed
authors.initials: A
authors.lastname: Hamdy
authors.affiliation: 4 Department of Nephrology, Hamad Medical Corporation , Doha, Qatar .
authors.forename: Awad
authors.initials: A
authors.lastname: Rashid
authors.affiliation: 1 Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut , Beirut, Lebanon .
authors.forename: Sarah
authors.initials: S
authors.lastname: Moodad
authors.affiliation: 5 Department of Medicine, South Texas Veterans Healthcare System and the University of Texas Health Science Center , San Antonio, Texas.
authors.forename: Karen
authors.initials: K
authors.lastname: Block
authors.affiliation: 5 Department of Medicine, South Texas Veterans Healthcare System and the University of Texas Health Science Center , San Antonio, Texas.
authors.forename: Yves
authors.initials: Y
authors.lastname: Gorin
authors.affiliation: 5 Department of Medicine, South Texas Veterans Healthcare System and the University of Texas Health Science Center , San Antonio, Texas.
authors.forename: Hanna E
authors.initials: HE
authors.lastname: Abboud
authors.affiliation: 1 Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut , Beirut, Lebanon .
authors.forename: Assaad A
authors.initials: AA
authors.lastname: Eid
mesh_terms: D000818:Animals; D017209:Apoptosis; D002352:Carrier Proteins / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000150:complications* / Q000235:genetics / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000150:complications* / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D000076225:Mechanistic Target of Rapamycin Complex 2; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D046912:Multiprotein Complexes / Q000378:metabolism*; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000235:genetics* / Q000378:metabolism; D050199:Podocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D000076226:Rapamycin-Insensitive Companion of mTOR Protein; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D046912:Multiprotein Complexes; C407223:NPHS2 protein; D000076226:Rapamycin-Insensitive Companion of mTOR Protein; D017382:Reactive Oxygen Species; C525637:rictor protein, mouse; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C422943:Nox4 protein, mouse; D000076225:Mechanistic Target of Rapamycin Complex 2; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D005947:Glucose
keywords: NADPH oxidases; diabetic nephropathy; mTORC2; reactive oxygen species