title: PLD1 regulates adipogenic differentiation through mTOR - IRS-1 phosphorylation at serine 636/639.
abstract: Phospholipase D1 (PLD1) plays a known role in several differentiation processes, but its role in adipogenic differentiation remains unknown. In the present study, we identified PLD1 as a negative regulator of adipogenic differentiation. We showed that PLD activity was downregulated by both 3-Isobutyl-1-methylxanthine (IBMX) and insulin upon induction of differentiation in 3T3-L1 adipogenic cells. In line with this observation, PLD activity decreased in both high fat diet (HFD)-fed mice and ob/ob mice. We also found that differentiation of 3T3-L1 preadipocytes was enhanced by the depletion of PLD1 levels or inhibition of PLD1 activity by VU0155069, a PLD1-specific inhibitor. Conversely, treatment with phosphatidic acid (PA), a PLD product, and overexpression of PLD1 both caused a decrease in adipogenic differentiation. Moreover, the elevated differentiation in PLD1-knockdown 3T3-L1 cells was reduced by either PA treatment or PLD1 expression, confirming negative roles of PLD1 and PA in adipogenic differentiation. Further investigation revealed that PA displaces DEP domain-containing mTOR-interacting protein (DEPTOR) from mTORC1, which subsequently phosphorylates insulin receptor substrate-1 (IRS-1) at serine 636/639 in 3T3-L1 cells. Taken together, our findings provide convincing evidence for a direct role of PLD1 in adipogenic differentiation by regulating IRS-1 phosphorylation at serine 636/639 through DEPTOR displacement and mTOR activation.
authors.affiliation: Department of Molecular Medicine, School of Medicine, Gachon University, Incheon 406-840, Republic of Korea.
authors.forename: Hae-In
authors.initials: HI
authors.lastname: Song
authors.affiliation: Department of Molecular Medicine, School of Medicine, Gachon University, Incheon 406-840, Republic of Korea.
authors.forename: Mee-Sup
authors.initials: MS
authors.lastname: Yoon
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D050156:Adipogenesis / Q000187:drug effects; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010712:Phosphatidic Acids / Q000494:pharmacology; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010880:Piperidines / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D001562:Benzimidazoles; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; C585271:N-(1-(4-(5-chloro-2-oxo-2,3-dihydro-1H-benzo(d)imidazol-1-yl)piperidin-1-yl)propan-2-yl)-2-naphthamide; D010712:Phosphatidic Acids; D010880:Piperidines; D034741:RNA, Small Interfering; C570841:deptor protein, mouse; D012694:Serine; D058570:TOR Serine-Threonine Kinases; D010739:Phospholipase D; C106801:phospholipase D1