title: A very-low-protein diet ameliorates advanced diabetic nephropathy through autophagy induction by suppression of the mTORC1 pathway in Wistar fatty rats, an animal model of type 2 diabetes and obesity.
abstract: The efficacy of a low-protein diet (LPD) on diabetic nephropathy is controversial. We aimed to investigate the renoprotective effects of an LPD and the underlying molecular mechanism in a rat model of type 2 diabetes and obesity.
  
  
  
  Diabetic male Wistar fatty (fa/fa) rats (WFRs) were treated with a standard diet (23.84% protein) or an LPD (5.77% protein) for 20 weeks from 24 weeks of age. We investigated the effect of the LPD on renal function, fibrosis, tubular cell damage, inflammation, mitochondrial morphology of proximal tubular cells (PTCs), apoptosis, autophagy and activation of mammalian target of rapamycin complex 1 (mTORC1).
  
  
  
  Kidney weight, albuminuria, excretion of urinary liver-type fatty acid binding protein, levels of plasma cystatin C and changes in renal histology, including fibrosis, tubular cell damage and inflammation, were aggravated in WFRs compared with non-diabetic Wistar lean rats (WLRs). Fragmented and swelling mitochondria accumulated in PTCs and apoptosis were enhanced in the kidney of WFRs. Immunohistochemical staining of p62 and p-S6 ribosomal protein (p-S6RP) in the tubular lesions of WFRs was increased compared with WLRs. The LPD intervention clearly ameliorated damage as shown by the assessment of renal function and histology, particularly tubulointerstitial damage in diabetic kidneys. Additionally, the 5.77% LPD, but not the 11.46% LPD, significantly suppressed p-S6RP levels and increased microtubule-associated protein light chain 3-II levels in the renal cortex. The LPD intervention partially decreased HbA1c levels in WFRs, and no differences in mean BP were observed among any of the groups.
  
  
  
  A very-low-protein diet improved advanced diabetic renal injuries, including tubulointerstitial damage, by restoring autophagy through the suppression of the mTORC1 pathway.
authors.affiliation: Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa, Japan. kitta@kanazawa-med.ac.jp.|Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan, 920-0293. kitta@kanazawa-med.ac.jp.
authors.forename: Munehiro
authors.initials: M
authors.lastname: Kitada
authors.affiliation: Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan, 920-0293.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Ogura
authors.affiliation: Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan, 920-0293.
authors.forename: Taeko
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa, Japan.|Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan, 920-0293.
authors.forename: Shi
authors.initials: S
authors.lastname: Sen
authors.affiliation: Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa, Japan.|Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan, 920-0293.
authors.forename: Seon Myeong
authors.initials: SM
authors.lastname: Lee
authors.affiliation: Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa, Japan.|Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan, 920-0293.
authors.forename: Keizo
authors.initials: K
authors.lastname: Kanasaki
authors.affiliation: Department of Medicine, Shiga University of Medical Science, Ōtsu, Shiga, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Kume
authors.affiliation: Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa, Japan. koya0516@kanazawa-med.ac.jp.|Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan, 920-0293. koya0516@kanazawa-med.ac.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Koya
mesh_terms: D000818:Animals; D001343:Autophagy / Q000235:genetics / Q000502:physiology*; D003924:Diabetes Mellitus, Type 2 / Q000178:diet therapy* / Q000378:metabolism* / Q000473:pathology; D003928:Diabetic Nephropathies / Q000178:diet therapy* / Q000378:metabolism* / Q000473:pathology; D018753:Diet, Protein-Restricted; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D008297:Male; D000076222:Mechanistic Target of Rapamycin Complex 1; D046529:Microscopy, Electron, Transmission; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009765:Obesity / Q000178:diet therapy / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D046912:Multiprotein Complexes; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases
keywords: Autophagy; Diabetic nephropathy; Low-protein diet; Mammalian target of rapamycin complex 1; Wistar fatty rat