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Eva Degerman

Eva Degerman

Professor

Eva Degerman

Differential regulation of adipocyte PDE3B in distinct membrane compartments by insulin and the beta(3)-adrenergic receptor agonist CL316243: effects of caveolin-1 knockdown on formation/maintenance of macromolecular signalling complexes

Author

  • Faiyaz Ahmad
  • Rebecka Lindh
  • Yan Tang
  • Iida Ruishalme
  • Anita Ost
  • Bobby Sahachartsiri
  • Peter Stralfors
  • Eva Degerman
  • Vincent C. Manganiello

Summary, in English

In adipocytes, PDE3B (phosphodiesterase 3B) is an important regulatory effector in signalling pathways controlled by insulin and cAMP-increasing hormones. Stimulation of 3T3-L1 adipocytes with insulin or the beta(3)-adrenergic receptor agonist CL316243 (termed CL) indicated that insulin preferentially phosphorylated/activated PDE3B associated with internal membranes (endoplasmic reticulum/Golgi), whereas CL preferentially phosphorylated/activated PDE3B associated with caveolae. siRNA (small interfering RNA)-mediated KD (knockdown) of CAV-1 (caveolin-1) in 3T3-L1 adipocytes resulted in down-regulation of expression of membrane-associated PDE3B. Insulin-induced activation of PDE3B was reduced, whereas CL-mediated activation was almost totally abolished. Similar results were obtained in adipocytes from Cav-1-deficient mice. siRNA-mediated KID of CAV-1 in 3T3-L1 adipocytes also resulted in inhibition of CL-stimulated phosphorylation of HSL (hormone-sensitive lipase) and perilipin A, and of lipolysis. Superose 6 gel-filtration chromatography of solubilized membrane proteins from adipocytes stimulated with insulin or CL demonstrated the reversible assembly of distinct macromolecular complexes that contained P-32-phosphorylated PDE3B and signalling molecules thought to be involved in its activation. Insulin- and CL-induced macromolecular complexes were enriched in cholesterol, and contained certain common signalling proteins [14-3-3, PP2A (protein phosphatase 2A) and cav-1]. The complexes present in insulin-stimulated cells contained tyrosine-phosphorylated IRS-1 (insulin receptor substrate 1) and its downstream signalling proteins, whereas CL-activated complexes contained beta(3)-adrenergic receptor, PKA-RII [PKA (cAMP-dependent protein kinase)-regulatory subunit] and HSL. Insulin- and CL-mediated macromolecular complex formation was significantly inhibited by CAV-1 KID. These results suggest that cav-1 acts as a molecular chaperone or scaffolding molecule in cholesterol-rich lipid rafts that may be necessary for the proper stabilization and activation of PDE3B in response to CL and insulin.

Department/s

  • Insulin Signal Transduction

Publishing year

2009

Language

English

Pages

399-410

Publication/Series

Biochemical Journal

Volume

424

Document type

Journal article

Publisher

Portland Press

Topic

  • Biochemistry and Molecular Biology

Keywords

  • kinase A (PKA)
  • protein
  • insulin
  • caveolin-1
  • adipocyte
  • beta(3)-adrenergic receptor
  • phosphodiesterase 3 (PDE3)

Status

Published

Research group

  • Insulin Signal Transduction

ISBN/ISSN/Other

  • ISSN: 0264-6021