ATF4-dependent heme-oxygenase-1 attenuates diabetic nephropathy by inducing autophagy and inhibiting apoptosis in podocyte

Ren Fail. 2021 Dec;43(1):968-979. doi: 10.1080/0886022X.2021.1936040.

Abstract

Aim: Podocyte injury plays an important role in diabetic nephropathy (DN), yet the underlying molecular mechanisms of podocyte injury in DN is not clear. Here, we investigated the role of activating transcription factor 4 (ATF4) and HO-1 in DN-induced podocyte injury.

Methods: Protein expression was measured by western blotting (WB) and immunofluorescence. Cellular apoptosis was quantified by flow cytometry. ATF4 siRNA knockdown and HO-1 overexpression in podocyte were employed to evaluate the role of ER stress in DN-induced apoptosis and autophagy response. Urinary protein levels, nephrin expression, serum creatinine and BUN were evaluated and glomerulosclerosis was quantified by Periodic Acid-Schiff staining.

Results: Expression of ATF4 was increased in podocytes exposed to serum from DN mice. ATF4 knockdown enhanced DN-induced podocyte apoptosis. HO-1 overexpression reduced the decline of DN-induced podocyte autophagy and inhibited apoptosis and the beneficial effects of HO-1 overexpression in DN were blocked by ATF4 knockdown. The diabetic mice were significantly ameliorated by HO-1 agonist hemin treatment.

Conclusions: ATF4 induces autophagy by enhancing the expression of HO-1, and inhibits podocyte apoptosis in DN. Treatment with the HO-1 agonist reduced proteinuria, apoptosis, and enhanced autophagy response, and thus improved renal function in DN mice.

Keywords: ATF4; HO-1; Podocyte; autophagy; diabetic nephropathy.

MeSH terms

  • Activating Transcription Factor 4 / genetics
  • Activating Transcription Factor 4 / metabolism*
  • Animals
  • Apoptosis / drug effects
  • Autophagy / drug effects*
  • Diabetes Mellitus, Experimental / metabolism
  • Diabetic Nephropathies / metabolism
  • Glucose / pharmacology*
  • Heme Oxygenase-1 / antagonists & inhibitors
  • Heme Oxygenase-1 / genetics
  • Heme Oxygenase-1 / metabolism*
  • Male
  • Mice
  • Podocytes / drug effects
  • Podocytes / enzymology
  • Podocytes / pathology*
  • Proteinuria / drug therapy
  • RNA, Small Interfering / genetics
  • Signal Transduction / drug effects

Substances

  • Atf4 protein, mouse
  • RNA, Small Interfering
  • Activating Transcription Factor 4
  • Heme Oxygenase-1
  • Glucose

Grants and funding

This work was supported by the Construction of Key Projects by Zhejiang Provincial Ministry under Grant [Number WKJ-ZJ-1915, WKJ-ZJ-2017]; The Zhejiang Province Chinese Medicine Modernization Program under Grant [Number 2020ZX001]; The General Project of Zhejiang Education Department under Grant [Number Y201942823]; and Clinical and Experimental Research of YSHS Granule.