SNAP-25 is essential for cortical granule exocytosis in mouse eggs.
Synaptosome-associated protein of 25 kDa (SNAP-25) has been shown to play an important role in Ca2+-dependent exocytosis in neurons and endocrine cells. During fertilization, sperm-egg fusion induces cytosolic Ca2+ mobilization and subsequently Ca2+-dependent cortical granule (CG) exocytosis in eggs. However, it is not yet clear whether SNAP-25 is involved in this process. In this study, we determined the expression and function of SNAP-25 in mouse eggs. mRNA and SNAP-25 were detected in metaphase II (MII) mouse eggs by RT-PCR and immunoblot analysis, respectively. Next, to determine the function of SNAP-25, we evaluated the change in CG exocytosis with a membrane dye, tetramethylammonium-1,6-diphenyl-1,3,5-hexatriene, after microinjection of a botulinum neurotoxin A (BoNT/A), which selectively cleaves SNAP-25 in MII eggs. Sperm-induced CG exocytosis was significantly inhibited in the BoNT/A-treated eggs. The inhibition was attenuated by coinjection of SNAP-25. These results suggest that SNAP-25 may be involved in Ca2+-dependent CG exocytosis during fertilization in mouse eggs.
Department of Obstetrics and Gynecology, Osaka University Medical School, Japan.
Y
Y
Ikebuchi
N
N
Masumoto
T
T
Matsuoka
T
T
Yokoi
M
M
Tahara
K
K
Tasaka
A
A
Miyake
Y
Y
Murata
D000818:Animals; D019274:Botulinum Toxins, Type A / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000502:physiology*; D004247:DNA / Q000032:analysis; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D005306:Fertilization / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism / Q000502:physiology*; D010063:Ovum / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D050825:Synaptosomal-Associated Protein 25; D014158:Transcription, Genetic
D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C494209:Snap25 protein, mouse; D050825:Synaptosomal-Associated Protein 25; D000001:Calcimycin; D004247:DNA; D019274:Botulinum Toxins, Type A