Phospholipase Cdelta4 is required for Ca2+ mobilization essential for acrosome reaction in sperm.
Zona pellucida (ZP)-induced acrosome reaction in sperm is a required step for mammalian fertilization. However, the precise mechanism of the acrosome reaction remains unclear. We previously reported that PLCdelta4 is involved in the ZP-induced acrosome reaction in mouse sperm. Here we have monitored Ca2+ responses in single sperm, and we report that the [Ca2+]i increase in response to ZP, which is essential for driving the acrosome reaction in vivo, is absent in PLCdelta4-/- sperm. Progesterone, another physiological inducer of the acrosome reaction, failed to induce sustained [Ca2+]i increases in PLCdelta4-/- sperm, and consequently the acrosome reaction was partially inhibited. In addition, we observed oscillatory [Ca2+]i increases in wild-type sperm in response to these acrosome inducers. Calcium imaging studies revealed that the [Ca2+]i increases induced by exposure to ZP and progesterone started at different sites within the sperm head, indicating that these agonists induce the acrosome reaction via different Ca2+ mechanisms. Furthermore, store-operated channel (SOC) activity was severely impaired in PLCdelta4-/- sperm. These results indicate that PLCdelta4 is an important enzyme for intracellular [Ca2+]i mobilization in the ZP-induced acrosome reaction and for sustained [Ca2+]i increases through SOC induced by ZP and progesterone in sperm.
Fukami
Kiyoko
K
Division of Biochemistry, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan. kfukami@ims.u-tokyo.ac.jp
Yoshida
Manabu
M
Inoue
Takafumi
T
Kurokawa
Manabu
M
Fissore
Rafael A
RA
Yoshida
Nobuaki
N
Mikoshiba
Katsuhiko
K
Takenawa
Tadaomi
T
D000177:Acrosome / Q000201:enzymology* / Q000648:ultrastructure; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000235:genetics; D019556:COS Cells; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D004527:Egg Proteins / Q000378:metabolism / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005306:Fertilization / Q000187:drug effects / Q000235:genetics*; D007527:Isoenzymes / Q000172:deficiency* / Q000235:genetics; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D054803:Phospholipase C delta; D011374:Progesterone / Q000378:metabolism / Q000494:pharmacology; D011956:Receptors, Cell Surface; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000172:deficiency* / Q000235:genetics; D000072216:Zona Pellucida Glycoproteins
D015220:Calcium Channels; D004527:Egg Proteins; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D000072216:Zona Pellucida Glycoproteins; D011374:Progesterone; D019284:Thapsigargin; D010738:Type C Phospholipases; D054803:Phospholipase C delta; C518031:Plcd4 protein, mouse; D002118:Calcium