title: CGI-58 facilitates lipolysis on lipid droplets but is not involved in the vesiculation of lipid droplets caused by hormonal stimulation.
abstract: A lipid droplet (LD)-associated protein, perilipin, is a critical regulator of lipolysis in adipocytes. We previously showed that Comparative Gene Identification-58 (CGI-58), a product of the causal gene of Chanarin-Dorfman syndrome, interacts with perilipin on LDs. In this study, we investigated the function of CGI-58 using RNA interference. Notably, CGI-58 knockdown caused an abnormal accumulation of LDs in both 3T3-L1 preadipocytes and Hepa1 hepatoma cells. CGI-58 knockdown did not influence the differentiation of 3T3-L1 adipocytes but reduced the activity of both basal and cAMP-dependent protein kinase-stimulated lipolysis. In vitro studies showed that CGI-58 itself does not have lipase/esterase activity, but it enhanced the activity of adipose triglyceride lipase. Upon lipolytic stimulation, endogenous CGI-58 was rapidly dispersed from LDs into the cytosol along with small particulate structures. This shift in localization depends on the phosphorylation of perilipin, because phosphorylated perilipin lost the ability to bind CGI-58. During lipolytic activation, LDs in adipocytes vesiculate into micro-LDs. Using coherent anti-Stokes Raman scattering microscopy, we pursued the formation of micro-LDs in single cells, which seemed to occur in cytoplasmic regions distant from the large central LDs. CGI-58 is not required for this process. Thus, CGI-58 facilitates lipolysis in cooperation with perilipin and other factors, including lipases.
authors.affiliation: Graduate School of Life Science, University of Hyogo, 3-2-1, Koto, Kamigori, Hyogo 678-1297, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Naoto
authors.initials: N
authors.lastname: Omatsu
authors.forename: Emi
authors.initials: E
authors.lastname: Morimoto
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakashima
authors.forename: Kanki
authors.initials: K
authors.lastname: Ueno
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Tanaka
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Satouchi
authors.forename: Fumiko
authors.initials: F
authors.lastname: Hirose
authors.forename: Takashi
authors.initials: T
authors.lastname: Osumi
mesh_terms: D051103:1-Acylglycerol-3-Phosphate O-Acyltransferase; D041721:3T3-L1 Cells; D000217:Acyltransferases; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D004950:Esterases / Q000235:genetics / Q000378:metabolism*; D006728:Hormones / Q000494:pharmacology*; D008049:Lipase / Q000235:genetics / Q000378:metabolism*; D050356:Lipid Metabolism / Q000187:drug effects; D008066:Lipolysis / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D000070778:Perilipin-1; D000070780:Perilipin-2; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D034622:RNA Interference; D051381:Rats
chemical_list: C520594:Abhd5 protein, rat; D002352:Carrier Proteins; D006728:Hormones; D008565:Membrane Proteins; D000070778:Perilipin-1; D000070780:Perilipin-2; D010750:Phosphoproteins; D000217:Acyltransferases; D051103:1-Acylglycerol-3-Phosphate O-Acyltransferase; C439972:ABHD5 protein, human; C492986:Abhd5 protein, mouse; D017868:Cyclic AMP-Dependent Protein Kinases; D004950:Esterases; D008049:Lipase