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Mol Cell Biol. 2014 Sep;34(17):3305-20. doi: 10.1128/MCB.00677-14. Epub 2014 Jun 23.

Susceptibility of Nrf2-null mice to steatohepatitis and cirrhosis upon consumption of a high-fat diet is associated with oxidative stress, perturbation of the unfolded protein response, and disturbance in the expression of metabolic enzymes but not with insulin resistance.

Author information

1
Medical Research Institute, Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom.
2
Division of Cancer Research, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom.
3
Department of Pathology, Ninewells Hospital and Medical School, Tayside NHS Trust, Dundee, Scotland, United Kingdom.
4
Division of Cancer Research, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom m.l.j.ashford@dundee.ac.uk j.d.hayes@dundee.ac.uk.
5
Medical Research Institute, Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, United Kingdom m.l.j.ashford@dundee.ac.uk j.d.hayes@dundee.ac.uk.

Abstract

Mice lacking the transcription factor NF-E2 p45-related factor 2 (Nrf2) develop more severe nonalcoholic steatohepatitis (NASH), with cirrhosis, than wild-type (Nrf2(+/+)) mice when fed a high-fat (HF) diet for 24 weeks. Although NASH is usually associated with insulin resistance, HF-fed Nrf2(-/-) mice exhibited better insulin sensitivity than HF-fed Nrf2(+/+) mice. In livers of HF-fed mice, loss of Nrf2 resulted in greater induction of lipogenic genes, lower expression of β-oxidation genes, greater reduction in AMP-activated protein kinase (AMPK) levels, and diminished acetyl coenzyme A (CoA) carboxylase phosphorylation than in the wild-type livers, which is consistent with greater fatty acid (FA) synthesis in Nrf2(-/-) livers. Moreover, primary Nrf2(-/-) hepatocytes displayed lower glucose and FA oxidation than Nrf2(+/+) hepatocytes, with FA oxidation partially rescued by treatment with AMPK activators. The unfolded protein response (UPR) was perturbed in control regular-chow (RC)-fed Nrf2(-/-) mouse livers, and this was associated with constitutive activation of NF-κB and JNK, along with upregulation of inflammatory genes. The HF diet elicited an antioxidant response in Nrf2(+/+) livers, and as this was compromised in Nrf2(-/-) livers, they suffered oxidative stress. Therefore, Nrf2 protects against NASH by suppressing lipogenesis, supporting mitochondrial function, increasing the threshold for the UPR and inflammation, and enabling adaptation to HF-diet-induced oxidative stress.

PMID:
24958099
PMCID:
PMC4135558
DOI:
10.1128/MCB.00677-14
[Indexed for MEDLINE]
Free PMC Article

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