Trans-10,cis-12 CLA increases adipocyte lipolysis and alters lipid droplet-associated proteins: role of mTOR and ERK signaling

J Lipid Res. 2005 May;46(5):885-95. doi: 10.1194/jlr.M400476-JLR200. Epub 2005 Feb 16.

Abstract

Lipid droplet-associated proteins play an important role in adipocyte triglyceride (TG) metabolism. Here, we show that trans-10,cis-12 conjugated linoleic acid (CLA), but not cis-9,trans-11 CLA, increased lipolysis and altered human adipocyte lipid droplet morphology. Before this change in morphology, there was a rapid trans-10,cis-12 CLA-induced increase in the accumulation of perilipin A in the cytosol, followed by the disappearance of perilipin A protein. In contrast, protein levels of adipose differentiation-related protein (ADRP) were increased in cultures treated with trans-10,cis-12 CLA. Immunostaining revealed that ADRP localized to the surface of small lipid droplets, displacing perilipin. Intriguingly, trans-10,cis-12 CLA increased ADRP protein expression to a much greater extent than ADRP mRNA without affecting stability, suggesting translational control of ADRP. To this end, we found that trans-10,cis-12 CLA increased activation of the mammalian target of rapamycin/p70 S6 ribosomal protein kinase/S6 ribosomal protein (mTOR/p70S6K/S6) pathway. Collectively, these data demonstrate that the trans-10,cis-12 CLA-mediated reduction of human adipocyte TG content is associated with the differential localization and expression of lipid droplet-associated proteins. This process involves both the translational control of ADRP through the activation of mTOR/p70S6K/S6 signaling and transcriptional control of perilipin A.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adipocytes / drug effects*
  • Adipocytes / enzymology
  • Adipocytes / metabolism
  • Adolescent
  • Adult
  • Base Sequence
  • Carrier Proteins
  • DNA Primers
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Female
  • Humans
  • Linoleic Acids, Conjugated / pharmacology*
  • Lipolysis*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Microscopy, Fluorescence
  • Middle Aged
  • Perilipin-1
  • Perilipin-2
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism
  • Polymerase Chain Reaction
  • Protein Kinases / metabolism*
  • Signal Transduction*
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases

Substances

  • Carrier Proteins
  • DNA Primers
  • Linoleic Acids, Conjugated
  • Membrane Proteins
  • PLIN2 protein, human
  • Perilipin-1
  • Perilipin-2
  • Phosphoproteins
  • Protein Kinases
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Extracellular Signal-Regulated MAP Kinases
  • Sirolimus