AKAP6 and phospholamban colocalize and interact in HEK-293T cells and primary murine cardiomyocytes.

Phospholamban (PLN) is an important Ca2+ modulator at the sarcoplasmic reticulum (SR) of striated muscles. It physically interacts and inhibits sarcoplasmic reticulum Ca2+ ATPase (SERCA2) function, whereas a protein kinase A (PKA)-dependent phosphorylation at its serine 16 reverses the inhibition. The underlying mechanism of this post-translational modification, however, remains not fully understood. Using publicly available databases, we identified A-kinase anchoring protein 6 (AKAP6) as a candidate that might play some roles in PLN phosphorylation. Immunofluorescence showed colocalization between GFP-AKAP6 and PLN in transfected HEK-293T cells and cultured mouse neonatal cardiomyocytes (CMNCs). Co-immunoprecipitation confirmed the functional interaction between AKAP6 and PLN in HEK-293T and isolated adult rat cardiomyocytes in response to isoproterenol stimulation. Functionally, AKAP6 promoted Ca2+ uptake activity of SERCA1 in cotransfected HEK-293T cells despite the presence of PLN. These results were further confirmed in adult rat cardiomyocytes. Immunofluorescence showed colocalization of both proteins around the perinuclear region, while protein-protein interaction was corroborated by immunoprecipitation of the nucleus-enriched fraction of rat hearts. Our findings suggest AKAP6 as a novel interacting partner to PLN in HEK-293T and murine cardiomyocytes. © 2019 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Citation

Farigol Hakem Zadeh, Allen C T Teng, Uros Kuzmanov, Paige J Chambers, Allan R Tupling, Anthony O Gramolini. AKAP6 and phospholamban colocalize and interact in HEK-293T cells and primary murine cardiomyocytes. Physiological reports. 2019 Jul;7(14):e14144

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PMID: 31325238

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