TY - JOUR
T1 - Guanylyl cyclase and cGMP-specific phosphodiesterase participate in the acrosome reaction of starfish sperm
AU - Kawase, Osamu
AU - Ueno, Seiichi
AU - Minakata, Hiroyuki
AU - Hoshi, Motonori
AU - Matsumoto, Midori
PY - 2004/11/1
Y1 - 2004/11/1
N2 - In the starfish, Asterias amurensis, the cooperation of three components of the egg jelly, i.e. ARIS (acrosome reaction-inducing substance), Co-ARIS and asterosap, is responsible for inducing the acrosome reaction. Experimentally, ARIS and asterosap are sufficient for the induction. However, when sperm are treated only with asterosap, they become unresponsive to the egg jelly to undergo the reaction. In this study, we analysed the mechanism of the acrosome reaction, using sperm inactivation by asterosap as a clue. Asterosap causes a rapid and transient increase in intracellular cGMP through the activation of the asterosap receptor, a guanylyl cyclase, and causes an increase in intracellular Ca2+. When sperm were pretreated with asterosap, the guanylyl cyclase seemed to be inactivated irreversibly by dephosphorylation. They were still responsive to ARIS but no longer to asterosap. However, in the presence of IBMX or zaprinast, inhibitors against phosphodiesterases (PDEs), they retained their capacity to undergo the acrosome reaction in response to the egg jelly or ARIS alone. IBMX and zaprinast suppressed the intracellular catabolism of cGMP, but not of cAMP. These results suggest that guanylyl cyclase and cGMP-specific, IBMX- and zaprinast-susceptible PDEs are involved in the regulation of the acrosome reaction.
AB - In the starfish, Asterias amurensis, the cooperation of three components of the egg jelly, i.e. ARIS (acrosome reaction-inducing substance), Co-ARIS and asterosap, is responsible for inducing the acrosome reaction. Experimentally, ARIS and asterosap are sufficient for the induction. However, when sperm are treated only with asterosap, they become unresponsive to the egg jelly to undergo the reaction. In this study, we analysed the mechanism of the acrosome reaction, using sperm inactivation by asterosap as a clue. Asterosap causes a rapid and transient increase in intracellular cGMP through the activation of the asterosap receptor, a guanylyl cyclase, and causes an increase in intracellular Ca2+. When sperm were pretreated with asterosap, the guanylyl cyclase seemed to be inactivated irreversibly by dephosphorylation. They were still responsive to ARIS but no longer to asterosap. However, in the presence of IBMX or zaprinast, inhibitors against phosphodiesterases (PDEs), they retained their capacity to undergo the acrosome reaction in response to the egg jelly or ARIS alone. IBMX and zaprinast suppressed the intracellular catabolism of cGMP, but not of cAMP. These results suggest that guanylyl cyclase and cGMP-specific, IBMX- and zaprinast-susceptible PDEs are involved in the regulation of the acrosome reaction.
KW - Acrosome reaction
KW - Guanylyl cyclase
KW - Phosphodiesterase
KW - Starfish
KW - cGMP
UR - http://www.scopus.com/inward/record.url?scp=14844310273&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=14844310273&partnerID=8YFLogxK
U2 - 10.1017/S0967199404002977
DO - 10.1017/S0967199404002977
M3 - Article
C2 - 15751545
AN - SCOPUS:14844310273
VL - 12
SP - 345
EP - 355
JO - Zygote
JF - Zygote
SN - 0967-1994
IS - 4
ER -