Mammalian phospholipase Czeta induces oocyte activation from the sperm perinuclear matrix.
Mammalian sperm-borne oocyte activating factor (SOAF) induces oocyte activation from a compartment that engages the oocyte cytoplasm, but it is not known how. A SOAF-containing extract (SE) was solubilized from the submembrane perinuclear matrix, a domain that enters the egg. SE initiated activation sufficient for full development. Microinjection coupled to tandem mass spectrometry enabled functional correlation profiling of fractionated SE without a priori assumptions about its chemical nature. Phospholipase C-zeta (PLCzeta) correlated absolutely with activating ability. Immunoblotting confirmed this and showed that the perinuclear matrix is the major site of 72-kDa PLCzeta. Oocyte activation was efficiently induced by 1.25 fg of sperm PLCzeta, corresponding to a fraction of one sperm equivalent (approximately 0.03). Immunofluorescence microscopy localized sperm head PLCzeta to a post-acrosomal region that becomes rapidly exposed to the ooplasm following gamete fusion. This multifaceted approach suggests a mechanism by which PLCzeta originates from an oocyte-penetrating assembly--the sperm perinuclear matrix--to induce mammalian oocyte activation at fertilization.
Fujimoto
Satoko
S
Laboratory of Mammalian Molecular Embryology, RIKEN Center for Developmental Biology, Chuo-ku, Kobe 650-0047, Japan.
Yoshida
Naoko
N
Fukui
Tomoyuki
T
Amanai
Manami
M
Isobe
Toshiaki
T
Itagaki
Chiharu
C
Izumi
Tomonori
T
Perry
Anthony C F
AC
D000818:Animals; D002458:Cell Fractionation; D005260:Female; D005306:Fertilization / Q000502:physiology; D006801:Humans; D008297:Male; D051379:Mice; D008845:Microinjections; D008969:Molecular Sequence Data; D015530:Nuclear Matrix / Q000737:chemistry / Q000201:enzymology; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D054801:Phosphoinositide Phospholipase C; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000737:chemistry / Q000166:cytology / Q000201:enzymology*; D013552:Swine; D010738:Type C Phospholipases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D010738:Type C Phospholipases; C499235:PLCZ1 protein, human; D054801:Phosphoinositide Phospholipase C; C499234:Plcz1 protein, mouse