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J Biol Chem. 2005 Dec 30;280(52):43109-20. Epub 2005 Oct 21.

Perilipin targets a novel pool of lipid droplets for lipolytic attack by hormone-sensitive lipase.

Author information

1
Center for Integrative Metabolic and Endocrine Research, the Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI 48201, USA.

Abstract

Adipocytes serve as the principal energy reservoir of the body; however, the subcellular organization of the machinery regulating lipid trafficking and metabolism is poorly understood. Mobilization of stored triglyceride is thought be controlled by interactions among intracellular lipases and proteins that coat lipid storage droplets. A major limitation of previous studies of hormone-mediated lipolysis, however, is the use of cultured model adipocytes whose three-dimensional architectures do not resemble those in real adipose tissue. To address this limitation, we investigated the intracellular targeting of perilipin, a major lipid coat protein, and hormone-sensitive lipase in three preparations that exhibit more appropriate morphologies: 3T3-L1 adipocytes grown in three-dimensional matrix, dissociated mature adipocytes from mouse adipose tissue, and adipocytes within intact fat pads. High resolution imaging of native and fluorescently tagged proteins indicate that: 1) perilipin preferentially targets a special class of peripheral lipid storage droplets, but not the major or central lipid storage droplets, 2) the peripheral droplets are the sites of attack by hormone-sensitive lipase, and 3) perilipin and hormone-sensitive lipase are continuously colocalized following lipolytic activation. These results indicate that in white adipose tissue, lipolysis takes place in a specialized subcellular domain that is distinct from the major lipid storage site and is defined by perilipin.

PMID:
16243839
DOI:
10.1074/jbc.M506336200
[Indexed for MEDLINE]
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