CaV3.2 T-type channels mediate Ca²⁺ entry during oocyte maturation and following fertilization.
Initiation of mouse embryonic development depends upon a series of fertilization-induced rises in intracellular Ca(2+). Complete egg activation requires influx of extracellular Ca(2+); however, the channels that mediate this influx remain unknown. Here, we tested whether the α1 subunit of the T-type channel CaV3.2, encoded by Cacna1h, mediates Ca(2+) entry into oocytes. We show that mouse eggs express a robust voltage-activated Ca(2+) current that is completely absent in Cacna1h(-/-) eggs. Cacna1h(-/-) females have reduced litter sizes, and careful analysis of Ca(2+) oscillation patterns in Cacna1h(-/-) eggs following in vitro fertilization (IVF) revealed reductions in first transient length and oscillation persistence. Total and endoplasmic reticulum (ER) Ca(2+) stores were also reduced in Cacna1h(-/-) eggs. Pharmacological inhibition of CaV3.2 in wild-type CF-1 strain eggs using mibefradil or pimozide reduced Ca(2+) store accumulation during oocyte maturation and reduced Ca(2+) oscillation persistence, frequency and number following IVF. Overall, these data show that CaV3.2 T-type channels have prev8iously unrecognized roles in supporting the meiotic-maturation-associated increase in ER Ca(2+) stores and mediating Ca(2+) influx required for the activation of development.
Reproductive and Developmental Biology Laboratory, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Miranda L
ML
Bernhardt
Reproductive and Developmental Biology Laboratory, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Yingpei
Y
Zhang
Neurobiology Laboratory, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Christian F
CF
Erxleben
Reproductive and Developmental Biology Laboratory, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Elizabeth
E
Padilla-Banks
Reproductive and Developmental Biology Laboratory, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Caitlin E
CE
McDonough
Key Laboratory of Animal Genetics, Breeding, and Reproduction of Ministry of Education, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
Yi-Liang
YL
Miao
Neurobiology Laboratory, National Institutes of Health, Research Triangle Park, NC 27709, USA.
David L
DL
Armstrong
Reproductive and Developmental Biology Laboratory, National Institutes of Health, Research Triangle Park, NC 27709, USA williamsc5@niehs.nih.gov.
Carmen J
CJ
Williams
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020747:Calcium Channels, T-Type / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism; D005260:Female; D005306:Fertilization / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*
C504883:Cacna1h protein, mouse; D020747:Calcium Channels, T-Type; D002118:Calcium
Ca2+; Egg activation; Fertilization; Meiosis; Oocyte; T-type channel