Abstract

The pathogenic mechanisms underlying the progression of non-alcoholic fatty liver disease (NAFLD) are not fully understood. In this study, we aimed to assess the relationship between endoplasmic reticulum (ER) stress and autophagy in human and mouse hepatocytes during NAFLD. ER stress and autophagy markers were analyzed in livers from patients with biopsy-proven non-alcoholic steatosis (NAS) or non-alcoholic steatohepatitis (NASH) compared with livers from subjects with histologically normal liver, in livers from mice fed with chow diet (CHD) compared with mice fed with high fat diet (HFD) or methionine-choline-deficient (MCD) diet and in primary and Huh7 human hepatocytes loaded with palmitic acid (PA). In NASH patients, significant increases in hepatic messenger RNA levels of markers of ER stress (activating transcription factor 4 (ATF4), glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP)) and autophagy (BCN1) were found compared with NAS patients. Likewise, protein levels of GRP78, CHOP and p62/SQSTM1 (p62) autophagic substrate were significantly elevated in NASH compared with NAS patients. In livers from mice fed with HFD or MCD, ER stress-mediated signaling was parallel to the blockade of the autophagic flux assessed by increases in p62, microtubule-associated protein 2 light chain 3 (LC3-II)/LC3-I ratio and accumulation of autophagosomes compared with CHD fed mice. In Huh7 hepatic cells, treatment with PA for 8 h triggered activation of both unfolding protein response and the autophagic flux. Conversely, prolonged treatment with PA (24 h) induced ER stress and cell death together with a blockade of the autophagic flux. Under these conditions, cotreatment with rapamycin or CHOP silencing ameliorated these effects and decreased apoptosis. Our results demonstrated that the autophagic flux is impaired in the liver from both NAFLD patients and murine models of NAFLD, as well as in lipid-overloaded human hepatocytes, and it could be due to elevated ER stress leading to apoptosis. Consequently, therapies aimed to restore the autophagic flux might attenuate or prevent the progression of NAFLD.

Autore Pugliese

• Fimia Gian Maria

Tutti gli autori

• González-Rodríguez A. , Mayoral R. , Agra N. , Valdecantos M. P. , Pardo V. , Miquilena-Colina M. E. , Vargas-Castrillón J. , Lo Iacono O. , Corazzari M. , Fimia G .M. , Piacentini M. , Muntané J. , Boscá L. , García-Monzón C. , Martín-Sanz P. , Valverde Á. M.

Titolo volume/Rivista

CELL DEATH & DISEASE

Anno di pubblicazione

2014

ISSN

2041-4889

ISBN

Non Disponibile

Numero di citazioni Wos

73

Ultimo Aggiornamento Citazioni

25/04/2018

Numero di citazioni Scopus

102

Ultimo Aggiornamento Citazioni

26/04/2018

Settori ERC

Non Disponibile

Codici ASJC

Non Disponibile