Regucalcin (RGN/SMP30) alters agonist- and thapsigargin-induced cytosolic [Ca2+] transients in cells by increasing SERCA Ca(2+)ATPase levels.

Regucalcin (RGN), also reported as senescence marker protein-30 (SMP30), plays a role in Ca(2+) homeostasis by modulating a number of Ca(2+)-dependent proteins. RGN also plays a cyto-protective role and its decrease is linked to age-related diseases and cell death. This study shows that RGN reduces agonist (histamine)-induced Ca(2+) transients in RGN(+) transfected COS-7 cells (RGN(+)) and also increases their Ca(2+) storage capacity. These observations are explained by RGN(+) cells having increased mRNA and protein expression levels of sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA). Therefore down-regulation of RGN expression may contribute to characteristics of age-dependent Ca(2+) homeostasis dis-regulation, by decreasing SERCA levels.