Alteration of expression of Ca²⁺ signaling proteins and adaptation of Ca²⁺ signaling in SERCA2^+/- mouse parotid acini

Purpose: The sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA), encoded by ATP2A2, is an essential component for G-protein coupled receptor (GPCR)-dependent Ca²⁺ signaling. However whether the changes in Ca²⁺ signaling and Ca²⁺ signaling proteins in parotid acinor cells are affected by a partial loss of SERCA2 are not known. Materials and Methods: In SERCA2^+/- mouse parotid gland acinar cells, Ca²⁺ signaling, expression levels of Ca²⁺ signaling proteins, and amylase secretion were investigated. Results: SERCA2^+/- mice showed decreased SERCA2 expression and an upregulation of the plasma membrane Ca²⁺ ATPase. A partial loss of SERCA2 changed the expression level of 1, 4, 5-tris-inositolphosphate receptors (IP₃Rs), but the localization and activities of IP₃Rs were not altered. In SERCA2^+/- mice, muscarinic stimulation resulted in greater amylase release, and the expression of synaptotagimin was increased compared to wild type mice. Conclusion. These results suggest that a partial loss of SERCA2 affects the expression and activity of Ca²⁺ signaling proteins in the parotid gland acini, however, overall Ca²⁺ signaling is unchanged.