Journal
BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR AND CELL BIOLOGY OF LIPIDS
Volume 1761, Issue 1, Pages 83-90Publisher
ELSEVIER
DOI: 10.1016/j.bbalip.2005.12.005
Keywords
perilipin; ubiquitination; proteasome; degradation; lipid droplet; fatty acid; triacylglycerol; adipose differentiation-related protein
Funding
- NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES [ZIADK015505, Z01DK015505] Funding Source: NIH RePORTER
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Perilipin protein coats the surface of intracellular lipid droplets and plays fundamental roles in lipid droplet formation and triacylglycerol hydrolysis. Perilipin is transcriptionally regulated through peroxisome proliferator-activated receptor and post-translationally stabilized by stored intracellular neutral lipids. In this study, we show that perilipin protein accumulates in transfected Chinese hamster ovary cells cultured in the presence of fatty acids but in turn is destabilized when lipid precursors for triacylglycerol synthesis are removed from culture serum. Adding fatty acids in the culture medium prevents the degradation of perilipin. Moreover, specific proteasome inhibitors, MG132, lactacystin, and ALLN, block the degradation, whereas inhibitors of other proteases are ineffective. Pulse-chase experiments confirm that perilipin is degraded through proteasome, a process that is inhibited by MG132 or ALLN and blunted by the addition of oleic acid. We have detected the coimmunoprecipitation of perilipin and ubiquitin, thus confirming that perilipin is conjugated to poly-ubiquitin and targeted for proteasomal degradation. Treatment with MG132 increases the expression of perilipin associated with lipid droplets as well as modestly throughout the cytosol. We conclude that the degradation of perilipin is mediated through all ubiquitination-proteasome pathway, which suggests another mode for the post-translational regulation of perilipin. Published by Elsevier B.V.
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