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Photo: KG Pressfoto

Marju Orho-Melander

Professor

Photo: KG Pressfoto

Patatin-like phospholipase domain-containing 3 (PNPLA3) I148M (rs738409) affects hepatic VLDL secretion in humans and in vitro

Author

  • Carlo Pirazzi
  • Martin Adiels
  • Maria Antonella Burza
  • Rosellina Margherita Mancina
  • Malin Levin
  • Marcus Stahlman
  • Marja-Riitta Taskinen
  • Marju Orho-Melander
  • Jeanna Perman
  • Arturo Pujia
  • Linda Andersson
  • Cristina Maglio
  • Tiziana Montalcini
  • Olov Wiklund
  • Jan Boren
  • Stefano Romeo

Summary, in English

Background & Aims: The robust association between non-alcoholic fatty liver disease (NAFLD) and the genetic variant I148M (rs738409) in PNPLA3 has been widely replicated. The aim of this study was to investigate the effect of the PNPLA3 I148M mutation on: (1) hepatic secretion of very low density lipoproteins (VLDL) in humans; and (2) secretion of apolipoprotein B (apoB) from McA-RH 7777 cells, which secrete VLDL-sized apoB-containing lipoproteins. Methods: VLDL kinetics was analyzed after a bolus infusion of stable isotopes in 55 overweight/obese men genotyped for the PNPLA3 I148M variant. Intracellular lipid content, apoB secretion and glycerolipid metabolism were studied in McA-RH 7777 cells overexpressing the human 1481 wild type or 148M mutant PNPLA3 protein. Results: In humans, carriers of the PNPLA3 148M allele had increased liver fat compared to 1481 homozygotes, and kinetic analysis showed a relatively lower secretion of the large, triglyceride-rich VLDL (VLDL1) in 148M carriers vs. 1481 homozygotes for the same amount of liver fat. McA-RH 7777 cells overexpressing the 148M mutant protein showed a higher intracellular triglyceride content with a lower apoB secretion and fatty acid efflux, compared to cells overexpressing the 1481 wild type protein. The responses with 148M matched those observed in cells expressing the empty vector, indicating that the mutation results in loss of function. Conclusions: We have shown that PNPLA3 affects the secretion of apoB-containing lipoproteins both in humans and in vitro and that the 148M protein is a loss-of-function mutation. We propose that PNPLA3 148M promotes intracellular lipid accumulation in the liver by reducing the lipidation of VLDL. (C) 2012 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

Department/s

  • Diabetes - Cardiovascular Disease
  • EXODIAB: Excellence of Diabetes Research in Sweden
  • EpiHealth: Epidemiology for Health

Publishing year

2012

Language

English

Pages

1276-1282

Publication/Series

Journal of Hepatology

Volume

57

Issue

6

Document type

Journal article

Publisher

Elsevier

Topic

  • Gastroenterology and Hepatology

Keywords

  • Genetic variant
  • Patatin-like phospholipase domain-containing 3
  • Liver
  • fat content
  • VLDL secretion
  • Apolipoprotein B
  • Lipolysis

Status

Published

Research group

  • Diabetes - Cardiovascular Disease

ISBN/ISSN/Other

  • ISSN: 0168-8278