| 1. |
- Ahmad, Faiyaz, et al.
(författare)
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Regulation of SERCA2 activity by PDE3A in human myocardium: Phosphorylation-dependent interaction of PDE3A1 with SERCA2.
- 2015
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 290:11, s. 6763-6776
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Tidskriftsartikel (refereegranskat)abstract
- PDE3 regulates cAMP-mediated signaling in the heart, and PDE3 inhibitors augment contractility in patients with heart failure. Studies in mice showed that PDE3A, not PDE3B, is the subfamily responsible for these inotropic effects, and that murine PDE3A1 associates with SERCA2, PLB and AKAP18 in a multi-protein signalosome in human SR. Immunohistochemical staining demonstrated that PDE3A co-localizes in Z-bands of human cardiac myocytes with desmin, SERCA2, PLB and AKAP18. In human SR fractions, cAMP increased PLB phosphorylation and SERCA2 activity; this was potentiated by PDE3 inhibition but not by PDE4 inhibition. During gel-filtration chromatography of solubilized SR membranes, PDE3 activity was recovered in distinct HMW and LMW peaks. HMW peaks contained PDE3A1 and PDE3A2, while LMW peaks contained PDE3A1, PDE3A2 and PDE3A3. Western blotting showed that endogenous HMW PDE3A1 was the principal PKA-phosphorylated isoform. Phosphorylation of endogenous PDE3A by rPKAc increased cAMP-hydrolytic activity, correlated with shift of PDE3A from LMW to HMW peaks, and increased co-immumoprecipitation of SERCA2, cav3, PKARII, PP2A and AKAP18 with PDE3A. In experiments with recombinant proteins, phosphorylation of rhPDE3A isoforms by rPKAc increased co-immumoprecipitation with rSERCA2 and rAKAP18. Deletion of the rhPDE3A1/PDE3A2 N-terminus blocked interactions with rSERCA2. Serine-to-alanine substitutions identified S292/S293, a site unique to hPDE3A1, as the principal site regulating its interaction with SERCA2. These results indicate that phosphorylation of hPDE3A1 at a PKA site in its unique N-terminal extension promotes its incorporation into SERCA2/AKAP18 signalosomes, where it regulates a discrete cAMP pool that controls contractility by modulating phosphorylation-dependent protein-protein interactions, PLB phosphorylation and SERCA2 activity.
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| 2. |
- Chung, Youn Wook, et al.
(författare)
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White to beige conversion in PDE3B KO adipose tissue through activation of AMPK signaling and mitochondrial function
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Understanding mechanisms by which a population of beige adipocytes is increased in white adipose tissue (WAT) reflects a potential strategy in the fight against obesity and diabetes. Cyclic adenosine monophosphate (cAMP) is very important in the development of the beige phenotype and activation of its thermogenic program. To study effects of cyclic nucleotides on energy homeostatic mechanisms, mice were generated by targeted inactivation of cyclic nucleotide phosphodiesterase 3b (Pde3b) gene, which encodes PDE3B, an enzyme that catalyzes hydrolysis of cAMP and cGMP and is highly expressed in tissues that regulate energy homeostasis, including adipose tissue, liver, and pancreas. In epididymal white adipose tissue (eWAT) of PDE3B KO mice on a SvJ129 background, cAMP/protein kinase A (PKA) and AMP-activated protein kinase (AMPK) signaling pathways are activated, resulting in "browning" phenotype, with a smaller increases in body weight under high-fat diet, smaller fat deposits, increased β-oxidation of fatty acids (FAO) and oxygen consumption. Results reported here suggest that PDE3B and/or its downstream signaling partners might be important regulators of energy metabolism in adipose tissue, and potential therapeutic targets for treating obesity, diabetes and their associated metabolic disorders.
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