Post-translational regulation of adipose differentiation-related protein by the ubiquitin/proteasome pathway.
Adipose differentiation-related protein (ADRP) is localized to lipid droplets in most mammalian cells. ADRP, proposed to regulate fatty acid mobilization and lipid droplet formation, is linked to lipid accumulation in foam cells of human atherosclerotic lesions. In this report, we show that ADRP protein accumulates in Chinese hamster ovary fibroblastic cells cultured in the presence of oleic acid but is destabilized when fatty acid sources are removed from culture serum. The latter effect was blocked by the proteasome inhibitor MG132, whereas inhibitors of other proteolytic processes were ineffective. Pulse-chase experiments confirmed that ADRP degradation is inhibited by MG132. Conditions that stimulate ADRP degradation also promoted the covalent modification of ADRP by ubiquitin, whereas the addition of oleic acid to culture media, which promotes triacylglycerol deposition, blunted the appearance of ubiquitinated-ADRP. Treatment with MG132 increased the levels of ADRP associated with lipid droplets, as well as throughout the cytosol. Finally, we demonstrate that the disappearance of ADRP protein after the onset of perilipin expression during adipocyte differentiation is due to degradation by proteasomes Thus, proteolytic degradation of ADRP mediated through the ubiquitin/proteasome pathway appears to be a major mode for the post-translational regulation of ADRP.
Xu
Guoheng
G
Department of Physiology and Pathophysiology, Health Science Center of Peking University and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing 100083, China.
Sztalryd
Carole
C
Lu
Xinyue
X
Tansey
John T
JT
Gan
Jaiwei
J
Dorward
Heidi
H
Kimmel
Alan R
AR
Londos
Constantine
C
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology; D000818:Animals; D015152:Blotting, Northern; D016466:CHO Cells; D002352:Carrier Proteins; D002454:Cell Differentiation; D006224:Cricetinae; D003470:Culture Media / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D015151:Immunoblotting; D047468:Immunoprecipitation; D007976:Leupeptins / Q000494:pharmacology; D008055:Lipids / Q000737:chemistry; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D019301:Oleic Acid / Q000737:chemistry; D000070778:Perilipin-1; D000070780:Perilipin-2; D010750:Phosphoproteins / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D013997:Time Factors; D014162:Transfection; D014280:Triglycerides / Q000737:chemistry / Q000378:metabolism; D025801:Ubiquitin / Q000737:chemistry / Q000378:metabolism*
D002352:Carrier Proteins; D003470:Culture Media; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D005227:Fatty Acids; D007976:Leupeptins; D008055:Lipids; D008565:Membrane Proteins; C000602982:PLIN2 protein, human; D000070778:Perilipin-1; D000070780:Perilipin-2; D010750:Phosphoproteins; C000602983:Plin2 protein, mouse; D014280:Triglycerides; D025801:Ubiquitin; D019301:Oleic Acid; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde