Calmodulin effects on steroids‐regulated plasma membrane calcium pump activity

Abstract

It is now generally accepted that non-genomic steroids action precedes their genomic effects by modulation of intracellular signaling pathways within seconds after application. Ca(2+) is a very potent and ubiquitous ion in all cells, and its concentration is precisely regulated. The most sensitive on Ca(2+) increase is ATP-consuming plasma membrane calcium pump (PMCA). The enzyme is coded by four genes, but isoforms diversity was detected in excitable and non-excitable cells. It is the only ion pump stimulated directly by calmodulin (CaM). We examined the role of PMCA isoforms composition and CaM effect in regulation of Ca(2+) uptake by estradiol, dehydroepiandrosterone (DHEA), pregnenolone (PREG), and their sulfates in a concentration range from 10(-9) to 10(-6) M, using the membranes from rat cortical synaptosomes, differentiated PC12 cells, and human erythrocytes. In excitable membranes with full set of PMCAs steroids apparently increased Ca(2+) uptake, although to a variable extent. In most of the cases, CaM decreased transport by 30-40% below controls. Erythrocyte PMCA was regulated by the steroids somewhat differently than excitable cells. CaM strongly increased the potency for Ca(2+) extrusion in membranes incubated with 17-beta-estradiol and PREG. Our results indicated that steroids may sufficiently control cytoplasmic calcium concentration within physiological and therapeutic range. The response depended on the cell type, PMCA isoforms expression profile, CaM presence, and the steroids structure.

Peripheral regulation by ecdysteroids of olfactory responsiveness in male Egyptian cotton leaf worms, Spodoptera littoralis

“…In vertebrates, CaM plays a role in olfactory adaptation of ORNs (Zheng et al, 2003;Pifferi et al, 2006;Spehr et al, 2009) and is modulated by steroids (Zylinska et al, 2009). In insect ORNs, repolarization depends on extracellular Ca 2þ and likely involves a Ca 2þ -and voltage-dependent K þ current (Pézier et al, 2007).…”

Nature, Calcigender, Nurture: Sex-dependent differential Ca2+ homeostasis as the undervalued third pillar

“…PMCAs of which four isoforms occur, keep the free Ca 2+ concentration in the nanomolar range. Zylinska et al [24]. also found that in excitable membranes (rat cortical synaptosomes) with a full set of PMCAs, estradiol, pregnenolone, dehydroepiandrosterone apparently increased Ca 2+ uptake.…”