The role of SERCA2a/PLN complex, Ca(2+) homeostasis, and anti-apoptotic proteins in determining cell fate
Vafiadaki E, Papalouka V, Arvanitis DA, Kranias EG, Sanoudou D. The role of SERCA2a/PLN complex, Ca(2+) homeostasis, and anti-apoptotic proteins in determining cell fate. Pflugers ArchPflugers ArchPflugers Arch. 2009;457:687-700.
Intracellular calcium is a major coordinator of numerous aspects of cellular physiology, including muscle contractility and cell survival. In cardiac muscle, aberrant Ca(2+) cycling has been implicated in a range of pathological conditions including cardiomyopathies and heart failure. The sarco(endo)plasmic reticulum Ca(2+) transport adenosine triphosphatase (SERCA2a) and its regulator phospholamban (PLN) have a central role in modulating Ca(2+) homeostasis and, therefore, cardiac function. Herein, we discuss the mechanisms through which SERCA2a and PLN control cardiomyocyte function in health and disease. Emphasis is placed on our newly identified PLN-binding partner HS-1-associated protein X-1 (HAX-1), which has an anti-apoptotic function and presents with numerous similarities to Bcl-2. Recent evidence indicates that proteins of the Bcl-2 family can influence ER Ca(2+) content, a critical determinant of cellular sensitivity to apoptosis. The discovery of the PLN/HAX-1 interaction therefore unveils an important new link between Ca(2+) homeostasis and cell survival, with significant therapeutic potential.