Orthovanadate decreases the leptin content in isolated mouse fat pads via proteasome activation
| Autor: | Aya Yoshida, Tetsuo Morita, Hiroshi Ueki, Ken Hirano, Toshio Motoyashiki |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Leptin
Male Proteasome Endopeptidase Complex medicine.medical_specialty Leupeptins Biophysics 8-Bromo Cyclic Adenosine Monophosphate Adipose tissue Mice Inbred Strains Cysteine Proteinase Inhibitors Biology Biochemistry Mice chemistry.chemical_compound Endopeptidase activity Multienzyme Complexes Internal medicine medicine Animals Insulin Vanadate Enzyme Inhibitors Molecular Biology Sodium orthovanadate Adenosine Triphosphatases Epididymis Sulfonamides Ubiquitin Isoquinolines Enzyme Activation Cysteine Endopeptidases Endocrinology Adipose Tissue chemistry Bupranolol Proteasome inhibitor Rabbits Vanadates Intracellular medicine.drug |
| Zdroj: | Archives of Biochemistry and Biophysics. 406:253-260 |
| ISSN: | 0003-9861 |
| Popis: | When isolated mouse fat pads were incubated with insulin or sodium orthovanadate (vanadate) for up to 4 h, the intracellular leptin content was increased by insulin, while it was decreased by vanadate. Bupranolol, a β 3 -adrenergic receptor antagonist, prevented both effects of vanadate, i.e., the decrease in intracellular leptin and increase in cellular cAMP content, while BRL 37344, a β 3 -adrenergic receptor antagonist mimicked the action of vanadate. H-89 prevented the vanadate-induced decrease in intracellular leptin, suggesting the involvement of a cAMP-dependent protein kinase (PKA). No detectable difference in the incorporation of [ 3 H]leucine into leptin was observed between incubations of the fat pads with and without vanadate, suggesting that the action of vanadate is independent of decreasing synthesis. Similar concentrations of MG-132, a membrane-permeable proteasome inhibitor, prevented the vanadate-induced decrease in both intracellular leptin content and leptin secretion, suggesting the involvement of the proteasome in the vanadate action. The proteasome fraction separated from the vanadate-treated fat pads increased the degradation of exogenous [ 125 I]leptin in the presence of an ATP-regenerating system together with an ubiqutination system. The endopeptidase activity against Cbz–Leu–Leu–Glu–β-naphthylamine also was increased by the proteasome fraction. MG-132 prevented both increased effects. The 8-Br–cAMP-treated proteasome fraction increased the degradation of the exogenous leptin. H-89 prevented the effect of 8-Br–cAMP. These results indicate that vanadate decreases the intracellular leptin content by increased degradation via a cAMP/PKA-dependent process involving proteasome activation. |
| Databáze: | OpenAIRE |
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