Stimulation of motility and respiration of intact fowl spermatozoa by calyculin A, a specific inhibitor of protein phosphatase-1 and -2A, via a Ca2+-dependent mechanism.
Intact fowl spermatozoa became almost immotile at 40 degrees C. In contrast, the presence of 10-1000 nmol calyculin A l-1, a specific inhibitor of protein phosphatase-1 (PP1) and -2A (PP2A), permitted activation of sperm motility in a dose-dependent manner. Calyculin A also stimulated the rate of oxygen consumption by spermatozoa, and induced a concomitant decrease in ATP concentrations, suggesting a coupling of ATP hydrolysis to the rate of oxidative phosphorylation. However, the motility and oxygen consumption of spermatozoa loaded with an intracellular Ca2+ chelator, 1,2-bis (2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, tetraacetoxymethyl ester (BAPTA/AM), were not stimulated by calyculin A alone, but only after the subsequent addition of 2 mmol CaCl2 l-1. These results suggest that inhibition of the activities of endogenous PP1 and PP2A may stimulate the motility and metabolic activity of fowl spermatozoa at 40 degrees C via a mechanism that requires intracellular free Ca2+.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002122:Calcium Chloride / Q000494:pharmacology; D002478:Cells, Cultured; D002645:Chickens; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism; D008297:Male; D008387:Marine Toxins; D010080:Oxazoles / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D054645:Protein Phosphatase 1; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects* / Q000502:physiology
D008387:Marine Toxins; D010080:Oxazoles; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; C059041:calyculin A; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D002122:Calcium Chloride; D002118:Calcium