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Suppression of insulin-induced gene 1 (INSIG1) function promotes hepatic lipid remodelling and restrains NASH progression.

Published version
Peer-reviewed

Type

Article

Change log

Authors

Azzu, Vian 
Vacca, Michele 
Kamzolas, Ioannis 
Hall, Zoe 
Leslie, Jack 

Abstract

OBJECTIVE: Non-alcoholic fatty liver disease (NAFLD) is a silent pandemic associated with obesity and the metabolic syndrome, and also increases cardiovascular- and cirrhosis-related morbidity and mortality. A complete understanding of adaptive compensatory metabolic programmes that modulate non-alcoholic steatohepatitis (NASH) progression is lacking. METHODS AND RESULTS: Transcriptomic analysis of liver biopsies in patients with NASH revealed that NASH progression is associated with rewiring of metabolic pathways, including upregulation of de novo lipid/cholesterol synthesis and fatty acid remodelling. The modulation of these metabolic programmes was achieved by activating sterol regulatory element-binding protein (SREBP) transcriptional networks; however, it is still debated whether, in the context of NASH, activation of SREBPs acts as a pathogenic driver of lipotoxicity, or rather promotes the biosynthesis of protective lipids that buffer excessive lipid accumulation, preventing inflammation and fibrosis. To elucidate the pathophysiological role of SCAP/SREBP in NASH and wound-healing response, we used an Insig1 deficient (with hyper-efficient SREBPs) murine model challenged with a NASH-inducing diet. Despite enhanced lipid and cholesterol biosynthesis, Insig1 KO mice had similar systemic metabolism and insulin sensitivity to Het/WT littermates. Moreover, activating SREBPs resulted in remodelling the lipidome, decreased hepatocellular damage, and improved wound-healing responses. CONCLUSIONS: Our study provides actionable knowledge about the pathways and mechanisms involved in NAFLD pathogenesis, which may prove useful for developing new therapeutic strategies. Our results also suggest that the SCAP/SREBP/INSIG1 trio governs transcriptional programmes aimed at protecting the liver from lipotoxic insults in NASH.

Description

Keywords

Carbon tetrachloride (CCl(4)), De novo lipogenesis (DNL), Lipid remodelling, Liver regeneration, Non-alcoholic fatty liver disease (NAFLD), Western diet, Animals, Biomarkers, Cholesterol, Diet, Western, Disease Progression, Female, Humans, Insulin Resistance, Intracellular Signaling Peptides and Proteins, Lipogenesis, Liver Cirrhosis, Male, Membrane Proteins, Mice, Mice, Inbred C57BL, Mice, Knockout, Middle Aged, Non-alcoholic Fatty Liver Disease, Transcriptome

Journal Title

Mol Metab

Conference Name

Journal ISSN

2212-8778
2212-8778

Volume Title

48

Publisher

Elsevier BV
Sponsorship
Medical Research Council (G0600717)
European Commission Horizon 2020 (H2020) Societal Challenges (634413)
Medical Research Council (MC_PC_13030)
MRC (MC_UU_00014/2)
MRC (MC_UU_00014/5)
British Heart Foundation (RG/18/7/33636)
British Heart Foundation (None)
Medical Research Council (MC_UU_12012/5)
Medical Research Council (G0802051)
Medical Research Council (MC_G0802535)
Medical Research Council (G0400192)
Medical Research Council (MC_UU_12012/2)
British Heart Foundation (FS/17/61/33473D)
Medical Research Council (MC_PC_12012)
Medical Research Council (G0600717/1)
NIHR Cambridge Biomedical Research Centre EU Horizon2020 (Grant Agreement 634413 – EpoS) Evelyn Trust