Liver-specific loss of lipin-1-mediated phosphatidic acid phosphatase activity does not mitigate intrahepatic TG accumulation in mice

George G. Schweitzer, Zhouji Chen, Connie Gan, Kyle S. McCommis, Nisreen Soufi, Roman Chrast, Mayurranjan S. Mitra, Kui Yang, Richard W. Gross, Brian N. Finck

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Lipin proteins (lipin 1, 2, and 3) regulate glycerolipid homeostasis by acting as phosphatidic acid phosphohydrolase (PAP) enzymes in the TG synthesis pathway and by regulating DNA-bound transcription factors to control gene transcription. Hepatic PAP activity could contribute to hepatic fat accumulation in response to physiological and pathophysiological stimuli. To examine the role of lipin 1 in regulating hepatic lipid metabolism, we generated mice that are deficient in lipin-1-encoded PAP activity in a liver-specific manner (Alb-Lpin1-/- mice). This allele of lipin 1 was still able to transcriptionally regulate the expression of its target genes encoding fatty acid oxidation enzymes, and the expression of these genes was not affected in Alb- Lpin1-/- mouse liver. Hepatic PAP activity was significantly reduced in mice with liver-specific lipin 1 deficiency. However, hepatocytes from Alb-Lpin1-/- mice had normal rates of TG synthesis, and steady-state hepatic TG levels were unaffected under fed and fasted conditions. Furthermore, Alb- Lpin1-/- mice were not protected from intrahepatic accumulation of diacylglyerol and TG after chronic feeding of a diet rich in fat and fructose. Collectively, these data demonstrate that marked deficits in hepatic PAP activity do not impair TG synthesis and accumulation under acute or chronic conditions of lipid overload.

Original languageEnglish
Pages (from-to)848-858
Number of pages11
JournalJournal of lipid research
Volume56
Issue number4
DOIs
StatePublished - Apr 1 2015

Keywords

  • Diacylglycerol
  • Fatty acid metabolism
  • Insulin signaling
  • Lipid
  • Phospholipids
  • Triglyceride

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