Accumulation of PNPLA3 on lipid droplets is the basis of associated hepatic steatosis

Soumik BasuRay, Yang Wang, Eriks Smagris, Jonathan C Cohen, Helen H Hobbs

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Fatty liver disease (FLD) is a disorder in which accumulation of triglycerides (TGs) in the liver can lead to inflammation, fibrosis, and cirrhosis. Previously, we identified a variant (I148M) in patatin-like phospholipase domain-containing protein 3 (PNPLA3) that is strongly associated with FLD, but the mechanistic basis for the association remains elusive. Although PNPLA3 has TG hydrolase activity in vitro, inactivation or overexpression of the WT protein in mice does not cause steatosis. In contrast, expression of two catalytically defective forms of PNPLA3 (I148M or S47A) in sucrose-fed mice causes accumulation of both PNPLA3 and TGs on hepatic lipid droplets (LDs). To determine if amassing PNPLA3 on LDs is a cause or consequence of steatosis, we engineered a synthetic isoform of PNPLA3 that uncouples protein accumulation from loss of enzymatic activity. Expression of a ubiquitylation-resistant form of PNPLA3 in mice caused accumulation of PNPLA3 on hepatic LDs and development of FLD. Lowering PNPLA3 levels by either shRNA knockdown or proteolysis-targeting chimera (PROTAC)-mediated degradation reduced liver TG content in mice overexpressing PNPLA3(148M). Taken together, our results show that the steatosis associated with PNPLA3(148M) is caused by accumulation of PNPLA3 on LDs.

Original languageEnglish (US)
Pages (from-to)9521-9526
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume116
Issue number19
DOIs
StatePublished - May 7 2019

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Phospholipases
Liver
Triglycerides
Fatty Liver
Liver Diseases
Lipid Droplets
Protein Domains
Fibrosis
Ubiquitination
Hydrolases
Small Interfering RNA
Proteolysis
Sucrose
Protein Isoforms
Proteins

Keywords

  • Autophagy
  • Fatty liver disease
  • Lipid droplet
  • PNPLA3
  • Proteasome

ASJC Scopus subject areas

  • General

Cite this

Accumulation of PNPLA3 on lipid droplets is the basis of associated hepatic steatosis. / BasuRay, Soumik; Wang, Yang; Smagris, Eriks; Cohen, Jonathan C; Hobbs, Helen H.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 116, No. 19, 07.05.2019, p. 9521-9526.

Research output: Contribution to journalArticle

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