Dose-dependent inhibition of mitochondrial ATP synthase by 17 beta-estradiol.
Mitochondria produce energy through oxidative phosphorylation. A key enzyme in this pathway is F0F1-ATP synthase, catalyzing ATP production from ADP and inorganic phosphate. Recently a subunit of F0F1-ATP synthase, oligomycin sensitivity-conferring protein, was identified as a new estradiol-binding protein. Estradiol could directly modulate mitochondrial ATP synthase activity through this subunit. In addition, intracellular ATP levels play a role in apoptotic death, which is an energy-dependent process requiring functioning mitochondria. Here we examined the effect of 17 beta-estradiol on F0F1-ATP synthase directly (in permeabilized cells) and in intact osteoclastic FLG 29.1 cells, a model of inducible apoptosis. The baseline F0F1-ATP synthase activity of FLG 29.1 cells was 4.485 nmol/min per mg. Estradiol rapidly inhibited F0F1-ATP synthase activity in the physiological range (half-inhibition concentration, IC50, of 30 nmol/l). With 1 nmol/l of estradiol, the inhibition was already significant (8-10% inhibition, p < 0.01) and with 100 nmol/l residual enzyme activity was only 15% (85% inhibition, p < 0.01). In addition, the effect of estradiol appeared to be directed towards F0F1-ATP synthase, since succinate-sustained respiration, uncoupled from the electron transport chain, was unaffected by estradiol. We assayed F0F1-ATP synthase activity in FLG 29.1 cells during inducible apoptosis. No significant difference of ATP synthesis was detected in apoptotic cells versus controls. In conclusion, we showed a new non-genomic effect of estradiol on a key mitochondrial enzyme, which thereby directly modulates cellular energy metabolism.
Massart
F
F
Scuola Superiore di Studi Universitari e di Perfezionamento S. Anna, Pisa, Italy.
Paolini
S
S
Piscitelli
E
E
Brandi
M L
ML
Solaini
G
G
D000255:Adenosine Triphosphate / Q000096:biosynthesis; D017209:Apoptosis; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000187:drug effects; D004072:Digitonin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000008:administration & dosage*; D004958:Estradiol / Q000008:administration & dosage*; D000091344:Filaggrin Proteins; D006801:Humans; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology*; D009840:Oligomycins / Q000494:pharmacology; D010010:Osteoclasts / Q000201:enzymology; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors* / Q000378:metabolism
D004791:Enzyme Inhibitors; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D009840:Oligomycins; D004958:Estradiol; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases; D004072:Digitonin