title: Modulation of mitochondrial Ca(2+) uptake by estrogen receptor agonists and antagonists.
abstract: Ca(2+) uptake by mitochondria is a key element in the control of cellular Ca(2+) homeostasis and Ca(2+)-dependent phenomena. It has been known for many years that this Ca(2+) uptake is mediated by the mitochondrial Ca(2+) uniporter, a specific Ca(2+) channel of the inner mitochondrial membrane. We have shown previously that this channel is strongly activated by a series of natural phytoestrogenic flavonoids. We show here that several agonists and antagonists of estrogen receptors (ERs) also modulate the activity of the uniporter. The specific alpha-ER agonist 4,4',4''-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT) was the strongest activator, increasing the rate of mitochondrial Ca(2+) uptake in permeabilized HeLa cells by 10-fold at 2 microM. Consistently, PPT largely increased the histamine-induced mitochondrial [Ca(2+)] peak and reduced the cytosolic one. Diethylstilbestrol and 17-beta-estradiol (but not 17-alpha-estradiol) were active at pharmacological concentrations while the beta-estrogen-receptor agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN) was little effective. The ER modulators tamoxifen and 4-hydroxy-tamoxifen inhibited mitochondrial Ca(2+) uptake (IC(50) 2.5+/-1.5 and 2.5+/-1.4 microM, mean+/-s.d., respectively) both in the presence and in the absence of PPT, but raloxifene and the pure estrogen antagonist ICI 182,780 produced no effect. Activation by PPT was immediate and inhibition by tamoxifen or 4-hydroxy-tamoxifen required only 5 min to reach maximum. Tamoxifen did not modify mitochondrial membrane potential and PPT induced a slow mitochondrial depolarization at higher concentrations than those required to activate mitochondrial Ca(2+) uptake. These results suggest that some kind of ER or related protein located in mitochondria controls the activity of the Ca(2+) uniporter by a nongenomic mechanism. This novel mechanism of action of estrogen agonists and antagonists can provide a new interpretation for several previously reported effects of these compounds.
authors.affiliation: Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Departamento de Bioquímica y Biología Molecular y Fisiología, Facultad de Medicina, Ramón y Cajal 7, E-47005 Valladolid, Spain.
authors.forename: Carmen D
authors.initials: CD
authors.lastname: Lobatón
authors.forename: Laura
authors.initials: L
authors.lastname: Vay
authors.forename: Esther
authors.initials: E
authors.lastname: Hernández-Sanmiguel
authors.forename: Jaime
authors.initials: J
authors.lastname: Santodomingo
authors.forename: Alfredo
authors.initials: A
authors.lastname: Moreno
authors.forename: Mayte
authors.initials: M
authors.lastname: Montero
authors.forename: Javier
authors.initials: J
authors.lastname: Alvarez
mesh_terms: D000331:Aequorin / Q000096:biosynthesis / Q000235:genetics; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects*; D045744:Cell Line, Tumor; D004054:Diethylstilbestrol / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology; D005260:Female; D006367:HeLa Cells; D006801:Humans; D049408:Luminescent Agents; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009942:Organometallic Compounds; D010636:Phenols / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology*; D011960:Receptors, Estrogen / Q000819:agonists* / Q000037:antagonists & inhibitors; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology*; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D014162:Transfection
chemical_list: D015220:Calcium Channels; D004965:Estrogen Antagonists; D004968:Estrogens, Non-Steroidal; D049408:Luminescent Agents; D009942:Organometallic Compounds; D010636:Phenols; D011720:Pyrazoles; D011960:Receptors, Estrogen; D020845:Selective Estrogen Receptor Modulators; C034703:mitochondrial calcium uniporter; C110932:tetramethyl rhodamine ethyl ester; D013629:Tamoxifen; C486184:4,4',4''-(4-propyl-((1)H)-pyrazole-1,3,5-triyl) tris-phenol; C016601:afimoxifene; D004958:Estradiol; D000331:Aequorin; D004054:Diethylstilbestrol; D002118:Calcium