A sequence variation (I148M) in PNPLA3 associated with nonalcoholic fatty liver disease disrupts triglyceride hydrolysis

Shaoqing He, Christopher McPhaul, John Zhong Li, Rita Garuti, Lisa Kinch, Nick V. Grishin, Jonathan C. Cohen, Helen H. Hobbs

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Abstract

Obesity and insulin resistance are associated with deposition of triglycerides in tissues other than adipose tissue. Previously, we showed that a missense mutation (I148M) in PNPLA3 (patatin-like phospholipase domain-containing 3 protein) is associated with increased hepatic triglyceride content in humans. Here we examined the effect of the I148M substitution on the enzymatic activity and cellular location of PNPLA3. Structural modeling predicted that the substitution of methionine for isoleucine at residue 148 would restrict access of substrate to the catalytic serine at residue 47. In vitro assays using recombinant PNPLA3partially purified from Sf9 cells confirmed that the wild type enzyme hydrolyzes emulsified triglyceride and that the I148M substitution abolishes this activity. Expression of PNPLA3-I148M, but not wild type PNPLA3, in cultured hepatocytes or in the livers of mice increased cellular triglyceride content. Cell fractionation studies revealed that ∼90% of wild type PNPLA3 partitioned between membranes and lipid droplets; substitution of isoleucine for methionine at position 148 did not alter the subcellular distribution of the protein. These data are consistent with PNPLA3-I148M promoting triglyceride accumulation by limiting triglyceride hydrolysis.

Original languageEnglish (US)
Pages (from-to)6706-6715
Number of pages10
JournalJournal of Biological Chemistry
Volume285
Issue number9
DOIs
StatePublished - Feb 26 2010

Fingerprint

Liver
Hydrolysis
Triglycerides
Substitution reactions
Isoleucine
Methionine
Tissue
Cell Fractionation
Sf9 Cells
Phospholipases
Missense Mutation
Membrane Lipids
Fractionation
Serine
Insulin Resistance
Non-alcoholic Fatty Liver Disease
Adipose Tissue
Hepatocytes
Assays
Proteins

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology
  • Medicine(all)

Cite this

A sequence variation (I148M) in PNPLA3 associated with nonalcoholic fatty liver disease disrupts triglyceride hydrolysis. / He, Shaoqing; McPhaul, Christopher; Li, John Zhong; Garuti, Rita; Kinch, Lisa; Grishin, Nick V.; Cohen, Jonathan C.; Hobbs, Helen H.

In: Journal of Biological Chemistry, Vol. 285, No. 9, 26.02.2010, p. 6706-6715.

Research output: Contribution to journalArticle

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