Estrogens diversely affect various physiological processes by genomic or non-genomic mechanisms, in both excitable and non-excitable cells. Additional to the trophic effects of estrogens promoting cell growth and differentiation, recent experimental evidence highlights their involvement in the regulation of intracellular Ca2+ homeostasis. The effects of estrogens on excitable cells are well documented. However, these steroids also influence numerous physiological events in non-excitable cells, such as fibroblasts or vascular endothelial cells. We have focused our attention on an immortalized endothelial-like cell line derived from fetal bovine cerebellum. Estradiol (E2) effects on intracellular Ca2+ homeostasis were tested by varying the exposure time to the hormone (8, 24, 48 h). Calcium measurements were performed with genetically encoded Ca2+ probes (Cameleons) targeted to the main subcellular compartments involved in intracellular Ca2+ homeostasis (cytosol, endoplasmic reticulum, mitochondria). Mitochondrial Ca2+ uptake significantly decreased after 48-h exposure to E2, whereas cytosolic and endoplasmic reticulum responses were unaffected. The effect of E2 on mitochondrial Ca2+ handling was blocked by ICI 182,780, a pure estrogen receptor antagonist, suggesting that the effect was estrogen-receptor– mediated. To evaluate whether the decrease of Ca2+ uptake affected mitochondrial membrane potential (ΔΨm), cells were monitored in the presence of tetra-methyl-rhodamine methylester; no significant changes were seen between cells treated with E2 and controls. To investigate a mechanism of action, we assessed the possibile involvement of the permeability transition pore (PTP), an inner mitochondrial membrane channel influencing energy metabolism and cell viability. We treated cells with CyclosporinA (CsA), which binds to the matrix chaperone cyclophilin-D and regulates PTP opening. CsA reversed the effects of a 48-h treatment with E2, suggesting a possible transcriptional modulation of proteins involved in the mitochondrial permeability transition process.
Estradiol effects on intracellular Ca2+ homeostasis in bovine brain-derived endothelial cells
SUMAN, MATTEO;GIACOMELLO, MARTA;CORAIN, LIVIO;BALLARIN, CRISTINA;MONTELLI, STEFANO;COZZI, BRUNO;PERUFFO, ANTONELLA
2012
Abstract
Estrogens diversely affect various physiological processes by genomic or non-genomic mechanisms, in both excitable and non-excitable cells. Additional to the trophic effects of estrogens promoting cell growth and differentiation, recent experimental evidence highlights their involvement in the regulation of intracellular Ca2+ homeostasis. The effects of estrogens on excitable cells are well documented. However, these steroids also influence numerous physiological events in non-excitable cells, such as fibroblasts or vascular endothelial cells. We have focused our attention on an immortalized endothelial-like cell line derived from fetal bovine cerebellum. Estradiol (E2) effects on intracellular Ca2+ homeostasis were tested by varying the exposure time to the hormone (8, 24, 48 h). Calcium measurements were performed with genetically encoded Ca2+ probes (Cameleons) targeted to the main subcellular compartments involved in intracellular Ca2+ homeostasis (cytosol, endoplasmic reticulum, mitochondria). Mitochondrial Ca2+ uptake significantly decreased after 48-h exposure to E2, whereas cytosolic and endoplasmic reticulum responses were unaffected. The effect of E2 on mitochondrial Ca2+ handling was blocked by ICI 182,780, a pure estrogen receptor antagonist, suggesting that the effect was estrogen-receptor– mediated. To evaluate whether the decrease of Ca2+ uptake affected mitochondrial membrane potential (ΔΨm), cells were monitored in the presence of tetra-methyl-rhodamine methylester; no significant changes were seen between cells treated with E2 and controls. To investigate a mechanism of action, we assessed the possibile involvement of the permeability transition pore (PTP), an inner mitochondrial membrane channel influencing energy metabolism and cell viability. We treated cells with CyclosporinA (CsA), which binds to the matrix chaperone cyclophilin-D and regulates PTP opening. CsA reversed the effects of a 48-h treatment with E2, suggesting a possible transcriptional modulation of proteins involved in the mitochondrial permeability transition process.
Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
