Metabolic profiling reveals that PNPLA3 induces widespread effects on metabolism beyond triacylglycerol remodeling in Huh-7 hepatoma cells.
PNPLA3 was recently associated with the susceptibility to nonalcoholic fatty liver disease, a common cause of chronic liver disease characterized by abnormal triglyceride accumulation. Although it is established that PNPLA3 has both triacylglycerol lipase and acylglycerol O-acyltransferase activities, is still unknown whether the gene has any additional role in the modulation of the human liver metabolome. To uncover the functional role of PNPLA3 on liver metabolism, we performed high-throughput metabolic profiling of PNPLA3 siRNA-silencing and overexpression of wild-type and mutant Ile148Met variants (isoleucine/methionine substitution at codon 148) in Huh-7 cells. Metabolomic analysis was performed by using GC/MS and LC/MS platforms. Silencing of PNPLA3 was associated with a global perturbation of Huh-7 hepatoma cells that resembled a catabolic response associated with protein breakdown. A significant decrease in amino- and γ-glutamyl-amino acids and dipeptides and a significant increase in cysteine sulfinic acid, myo-inositol, lysolipids, sphingolipids, and polyunsaturated fatty acids were observed. Overexpression of the PNPLA3 Met148 variant mirrored many of the metabolic changes observed during gene silencing, but in the opposite direction. These findings were replicated by the exploration of canonical pathways associated with PNPLA3 silencing and Met148 overexpression. Overexpression of the PNPLA3 Met148 variant was associated with a 1.75-fold increase in lactic acid, suggesting a shift to anaerobic metabolism and mitochondrial dysfunction. Together, these results suggest a critical role of PNPLA3 in the modulation of liver metabolism beyond its classical participation in triacylglycerol remodeling.
Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, Virginia; and.
Hae-Ki
HK
Min
Department of Clinical and Molecular Hepatology and Molecular Genetics and Biology of Complex Diseases, Institute of Medical Research, IDIM, University of Buenos Aires-National Scientific and Technical Research Council (CONICET), Ciudad Autónoma de Buenos Aires, Argentina.
Silvia
S
Sookoian
Department of Clinical and Molecular Hepatology and Molecular Genetics and Biology of Complex Diseases, Institute of Medical Research, IDIM, University of Buenos Aires-National Scientific and Technical Research Council (CONICET), Ciudad Autónoma de Buenos Aires, Argentina.
Carlos J
CJ
Pirola
Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, Virginia; and.
Jianfeng
J
Cheng
Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, Virginia; and.
Faridoddin
F
Mirshahi
Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, Virginia; and asanyal@mcvh-vcu.edu.
Arun J
AJ
Sanyal
D015415:Biomarkers / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid; D008401:Gas Chromatography-Mass Spectrometry; D057166:High-Throughput Screening Assays; D006801:Humans; D008049:Lipase / Q000235:genetics / Q000378:metabolism*; D008113:Liver Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D055432:Metabolomics / Q000379:methods; D009154:Mutation; D009997:Osmotic Pressure; D034622:RNA Interference; D049490:Systems Biology; D053719:Tandem Mass Spectrometry; D014162:Transfection; D014280:Triglycerides / Q000378:metabolism*; D000217:Acyltransferases; D054512:Phospholipases A2, Calcium-Independent
D015415:Biomarkers; D008049:Lipase; D008565:Membrane Proteins; D014280:Triglycerides; C533682:PNPLA3 protein, human; D000217:Acyltransferases; D054512:Phospholipases A2, Calcium-Independent
Huh-7 cells; Ile148Met variant; PNPLA3; metabolome; nonalcoholic fatty liver disease; systems biology