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Cecilia Holm

Professor

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Activation of Hormone-sensitive Lipase Requires Two Steps, Protein Phosphorylation and Binding to the PAT-1 Domain of Lipid Droplet Coat Proteins

Author

  • Hong Wang
  • Liping Hu
  • Knut Dalen
  • Heidi Dorward
  • Amy Marcinkiewicz
  • Deanna Russell
  • Dawei Gong
  • Constantine Londos
  • Tomohiro Yamaguchi
  • Cecilia Holm
  • Mark A. Rizzo
  • Dawn Brasaemle
  • Carole Sztalryd

Summary, in English

Lipolysis is an important metabolic pathway controlling energy homeostasis through degradation of triglycerides stored in lipid droplets and release of fatty acids. Lipid droplets of mammalian cells are coated with one or more members of the PAT protein family, which serve important functions in regulating lipolysis. In this study, we investigate the mechanisms by which PAT family members, perilipin A, adipose differentiation-related protein (ADFP), and LSDP5, control lipolysis catalyzed by hormone-sensitive lipase (HSL), a major lipase in adipocytes and several non-adipose cells. We applied fluorescence microscopic tools to analyze proteins in situ in cultured Chinese hamster ovary cells using fluorescence recovery after photo-bleaching and anisotropy Forster resonance energy transfer. Fluorescence recovery after photobleaching data show that ADFP and LSDP5 exchange between lipid droplet and cytoplasmic pools, whereas perilipin A does not. Differences in protein mobility do not correlate with PAT protein-mediated control of lipolysis catalyzed by HSL or endogenous lipases. Forster resonance energy transfer and co-immunoprecipitation experiments reveal that each of the three PAT proteins bind HSL through interaction of the lipase with amino acids within the highly conserved amino-terminal PAT-1 domain. ADFP and LSDP5 bind HSL under basal conditions, whereas phosphorylation of serine residues within three amino-terminal protein kinase A consensus sequences of perilipin A is required for HSL binding and maximal lipolysis. Finally, protein kinase A-mediated phosphorylation of HSL increases lipolysis in cells expressing ADFP or LSDP5; in contrast, phosphorylation of perilipin A exerts the major control over HSL-mediated lipolysis when perilipin is the main lipid droplet protein.

Department/s

  • Molecular Endocrinology

Publishing year

2009

Language

English

Pages

32116-32125

Publication/Series

Journal of Biological Chemistry

Volume

284

Issue

46

Document type

Journal article

Publisher

ASBMB

Topic

  • Endocrinology and Diabetes

Status

Published

Research group

  • Molecular Endocrinology

ISBN/ISSN/Other

  • ISSN: 1083-351X