Depletion of Essential Isoprenoids and ER Stress Induction Following Acute Liver-Specific Deletion of HMG-CoA Reductase

Authors

Marco De Giorgi
Kelsey E Jarrett
Jason C Burton
Alexandria M Doerfler
Ayrea Hurley
Ang Li
Rachel H Hsu
Mia Furgurson
Kalyani R Patel
Jun Han
Christoph H Borchers
William R Lagor

Publication Date

12-1-2020

Journal

Journal of Lipid Research

DOI

10.1194/jlr.RA120001006

PMID

33109681

PMCID

PMC7707164

PubMedCentral® Posted Date

10-27-2020

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

Hydroxymethylglutaryl CoA Reductases, Animals, Endoplasmic Reticulum Stress, Mice, Liver, Terpenes, Hepatocytes, Gene Deletion, Apoptosis, CRISPR-Cas Systems, Mevalonic Acid, Mice, Knockout, Dolichols, cholesterol synthesis and regulation, liver, endoplasmic reticulum, animal models, 3-hydroxy-3-methylglutaryl-coenzyme A, adeno-associated virus, dolichol, dehydrodolichyl diphosphate synthase subunit, clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9

Abstract

HMG-CoA reductase (Hmgcr) is the rate-limiting enzyme in the mevalonate pathway and is inhibited by statins. In addition to cholesterol, Hmgcr activity is also required for synthesizing nonsterol isoprenoids, such as dolichol, ubiquinone, and farnesylated and geranylgeranylated proteins. Here, we investigated the effects of Hmgcr inhibition on nonsterol isoprenoids in the liver. We have generated new genetic models to acutely delete genes in the mevalonate pathway in the liver using AAV-mediated delivery of Cre-recombinase (AAV-Cre) or CRISPR/Cas9 (AAV-CRISPR). The genetic deletion of Hmgcr by AAV-Cre resulted in extensive hepatocyte apoptosis and compensatory liver regeneration. At the biochemical level, we observed decreased levels of sterols and depletion of the nonsterol isoprenoids, dolichol and ubiquinone. At the cellular level, Hmgcr-null hepatocytes showed ER stress and impaired N-glycosylation. We further hypothesized that the depletion of dolichol, essential for N-glycosylation, could be responsible for ER stress. Using AAV-CRISPR, we somatically disrupted dehydrodolichyl diphosphate synthase subunit (Dhdds), encoding a branch point enzyme required for dolichol biosynthesis. Dhdds-null livers showed ER stress and impaired N-glycosylation, along with apoptosis and regeneration. Finally, the combined deletion of Hmgcr and Dhdds synergistically exacerbated hepatocyte ER stress. Our data show a critical role for mevalonate-derived dolichol in the liver and suggest that dolichol depletion is at least partially responsible for ER stress and apoptosis upon potent Hmgcr inhibition.

Comments

Associated Data