AKAP6 and phospholamban colocalize and interact in HEK‐293T cells and primary murine cardiomyocytes. Issue 14 (19th July 2019)

• Record Type: Journal Article
• Authors: Hakem Zadeh, Farigol; Teng, Allen C. T.; Kuzmanov, Uros; Chambers, Paige J.; Tupling, Allan R.; Gramolini, Anthony O.
• Is Part Of: Physiological reports. Volume 7:Issue 14(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-07-19
• Subjects: A‐kinase anchoring protein (AKAP) -- Ca2+ transport -- heart -- protein kinase A (PKA) -- sarcoplasmic reticulum (SR); Physiology -- Periodicals; 571
• DOI: 10.14814/phy2.14144
• Languages: English
• ISSNs: 2051-817X

Abstract

Abstract: Phospholamban (PLN) is an important Ca 2+ modulator at the sarcoplasmic reticulum (SR) of striated muscles. It physically interacts and inhibits sarcoplasmic reticulum Ca 2+ 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 Ca 2+ 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. Abstract : We identified muscle‐specific A‐kinase anchoring protein (mAKAP) as a candidate that might have a critical role in regulating PLN phosphorylation.