Effects of estrogen on PMCA 2 and 4 in human fibroblast-like synovial cells and mouse macrophage-like cells

We investigated the possible roles of estrogen on plasma membrane Ca 2+-ATPase (PMCA) in human fibroblast-like synovial cells (HELS) and mouse macrophage-like cells (RAW 264.7). Western blots revealed the expression of PMCA 2 and 4 in both cells. In vitro treatments with 17β-estradiol for 24 hours resulted in a concentration dependent decrease in PMCA expression. Moreover, Ca2+-ATPase specific activity was similarly decreased with estrogen treatments. However, treatments for 1 hour in the presence or absence of cycloheximide demonstrated non-significant effects. These results suggest that estrogen has a modulatory role on Ca2+ homeostasis through decreasing PMCA expression and abating their activity.