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

Abstract

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 acinar 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 synaptotagmin 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.