Regulation of FSP27 protein stability by AMPK and HSC70
| Autor: | Alicia M. Saarinen, Jun Liu, Xiaodong Zhang, Xitao Xie, Bradlee L. Heckmann |
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| Rok vydání: | 2014 |
| Předmět: |
Male
medicine.medical_specialty Physiology Protein catabolic process Ubiquitin-Protein Ligases Endocrinology Diabetes and Metabolism AMP-Activated Protein Kinases Cycloheximide Mice chemistry.chemical_compound AMP-activated protein kinase Ubiquitin 3T3-L1 Cells Physiology (medical) Internal medicine Adipocytes medicine Animals Protein kinase A biology Binding protein HSC70 Heat-Shock Proteins Proteins AMPK Articles Ribonucleotides Aminoimidazole Carboxamide Ubiquitin ligase Enzyme Activation Mice Inbred C57BL Endocrinology Biochemistry chemistry Gene Knockdown Techniques biology.protein |
| Zdroj: | American Journal of Physiology-Endocrinology and Metabolism. 307:E1047-E1056 |
| ISSN: | 1522-1555 0193-1849 |
| DOI: | 10.1152/ajpendo.00125.2014 |
| Popis: | Fat-specific protein 27 (FSP27) plays a pivotal role in controlling the formation of large lipid droplet and energy metabolism. The cellular levels of FSP27 are tightly regulated through the proteasomal ubiquitin-mediated degradation. However, the upstream signals that trigger FSP27 degradation and the underlying mechanism(s) have yet to be identified. Here we show that AMP-activated protein kinase (AMPK) activation by AICAR (5-amino-1-β-d-ribofuranosyl-imidazole-4-carboxamide) or phenformin induced the ubiquitination of FSP27 and promoted its degradation in 3T3-L1 adipocytes. The levels of FSP27 protein could be maintained by either knocking down AMPKα1 or blocking proteasomal pathway. Moreover, AICAR treatment induced multilocularization of LDs in 3T3-L1 adipocytes, reminiscent of the morphological changes in cells depleted of FSP27. Furthermore, mass spectrometry-based proteomic analysis identified heat shock cognate 70 (HSC70) as a novel binding protein of FSP27. The specific interaction was confirmed by co-immunoprecipitation of both ectopically expressed and endogenous proteins. Importantly, knockdown of HSC70 by small interference RNA resulted in increased half-life of FSP27 in cells treated with a protein synthesis inhibitor cycloheximide (CHX) or AICAR. However, silencing of the E3 ubiquitin ligase CHIP (COOH terminus of HSC70-interacting protein) failed to alter the stability of FSP27 protein under both conditions. Taken together, our data indicate that AMPK is a negative regulator of FSP27 stability through the proteasomal ubiquitin-dependent protein catabolic process. Promotion of FSP27 degradation may be an important factor responsible for the beneficial effect of AMPK activators on energy metabolism. |
| Databáze: | OpenAIRE |
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