TY - JOUR
T1 - Development of Ca2+-release mechanisms during oocyte maturation of the starfish Asterina pectinifera
AU - Takahashi, Isao
AU - Kyozuka, Keiichiro
N1 - Funding Information:
We thank Dr Ritsu Kuraishi (Keio University) for supply of animals from Tokyo and Drs Luigia Santella and Jong Tai Chun (Stazione Zoologica Anton Dohrn) for useful discussions and comments on the manuscript.
Publisher Copyright:
© Cambridge University Press 2016.
PY - 2016/12/1
Y1 - 2016/12/1
N2 - An important step for successful fertilization and further development is the increase in intracellular Ca2+ in the activated oocyte. It has been known that starfish oocytes become increasingly sensitive to inositol 1,4,5-trisphosphate (IP3) during meiotic maturation to exhibit highly efficient IP3-induced Ca2+ release (IICR) by the time of germinal vesicle breakdown (GVBD). However, we noted that the peak level of intracellular Ca2+ increase after insemination is already high in the maturing oocytes before GVBD. Using maturing oocytes before GVBD, we investigated Ca2+ release mechanisms other than IICR. We report here that Ca2+-release mechanisms dependent on nicotinic acid adenine dinucleotide phosphate (NAADP) and nicotinamide adenine dinucleotide (NADP), the precursor of NAADP, became functional prior to the development of IICR mechanisms. As with IP3, but unlike NAADP, the Ca2+ stores responsive to NADP are sensitized during the meiotic maturation induced by 1-methyladenine (1-MA). This suggests that the process may represent a physiological response to the maturation hormone. NADP-dependent Ca2+ release in immature oocytes, however, did not induce oocyte maturation by itself, but was enhanced by the conditions mimicking the increases of intracellular Ca2+ and pH that take place in the maturing oocytes of starfish.
AB - An important step for successful fertilization and further development is the increase in intracellular Ca2+ in the activated oocyte. It has been known that starfish oocytes become increasingly sensitive to inositol 1,4,5-trisphosphate (IP3) during meiotic maturation to exhibit highly efficient IP3-induced Ca2+ release (IICR) by the time of germinal vesicle breakdown (GVBD). However, we noted that the peak level of intracellular Ca2+ increase after insemination is already high in the maturing oocytes before GVBD. Using maturing oocytes before GVBD, we investigated Ca2+ release mechanisms other than IICR. We report here that Ca2+-release mechanisms dependent on nicotinic acid adenine dinucleotide phosphate (NAADP) and nicotinamide adenine dinucleotide (NADP), the precursor of NAADP, became functional prior to the development of IICR mechanisms. As with IP3, but unlike NAADP, the Ca2+ stores responsive to NADP are sensitized during the meiotic maturation induced by 1-methyladenine (1-MA). This suggests that the process may represent a physiological response to the maturation hormone. NADP-dependent Ca2+ release in immature oocytes, however, did not induce oocyte maturation by itself, but was enhanced by the conditions mimicking the increases of intracellular Ca2+ and pH that take place in the maturing oocytes of starfish.
KW - Inositol 1,4,5-trisphosphate (IP3)
KW - Intracellular Ca and pH
KW - Maturing oocyte
KW - Nicotinamide adenine dinucleotide (NADP)
KW - Nicotinic acid adenine dinucleotide phosphate (NAADP)
UR - http://www.scopus.com/inward/record.url?scp=84989818326&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84989818326&partnerID=8YFLogxK
U2 - 10.1017/S0967199416000186
DO - 10.1017/S0967199416000186
M3 - Article
C2 - 27692029
AN - SCOPUS:84989818326
VL - 24
SP - 857
EP - 868
JO - Zygote
JF - Zygote
SN - 0967-1994
IS - 6
ER -