title: Localization of ubiquitin C-terminal hydrolase L1 in mouse ova and its function in the plasma membrane to block polyspermy.
abstract: Protein degradation is essential for oogenesis and embryogenesis. The ubiquitin-proteasome system regulates many cellular processes via the rapid degradation of specific proteins. Ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) is exclusively expressed in neurons, testis, ovary, and placenta, each of which has unique biological activities. However, the functional role of UCH-L1 in mouse oocytes remains unknown. Here, we report the expression pattern of UCH-L1 and its isozyme UCH-L3 in mouse ovaries and embryos. Using immunocytochemistry, UCH-L1 was selectively detected on the plasma membrane, whereas UCH-L3 was mainly detected in the cytoplasm, suggesting that these isozymes have distinct functions in mouse eggs. To further investigate the functional role of UCH-L1 in mouse eggs, we analyzed the fertilization rate of UCH-L1-deficient ova of gad female mice. Female gad mice had a significantly increased rate of polyspermy in in vitro fertilization assays, although the rate of fertilization did not differ significantly from wild-type mice. In addition, the litter size of gad female mice was significantly reduced compared with wild-type mice. These results may identify UCH-L1 as a candidate for a sperm-oocyte interactive binding or fusion protein on the plasma membrane that functions during the block to polyspermy in mouse oocytes.
authors.affiliation: Department of Biomedical Science, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Tokyo 113-8657, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sekiguchi
authors.forename: Jungkee
authors.initials: J
authors.lastname: Kwon
authors.forename: Etsuko
authors.initials: E
authors.lastname: Yoshida
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hamasaki
authors.forename: Shizuko
authors.initials: S
authors.lastname: Ichinose
authors.forename: Makoto
authors.initials: M
authors.lastname: Hideshima
authors.forename: Mutsuki
authors.initials: M
authors.lastname: Kuraoka
authors.forename: Akio
authors.initials: A
authors.lastname: Takahashi
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ishii
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kyuwa
authors.forename: Keiji
authors.initials: K
authors.lastname: Wada
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yoshikawa
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000201:enzymology; D001947:Breeding; D002462:Cell Membrane / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D010053:Ovary / Q000166:cytology; D010060:Ovulation / Q000502:physiology; D010063:Ovum / Q000166:cytology* / Q000201:enzymology* / Q000648:ultrastructure; D021381:Protein Transport; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology*; D025801:Ubiquitin / Q000378:metabolism; D043222:Ubiquitin Thiolesterase / Q000378:metabolism*
chemical_list: D025801:Ubiquitin; D043222:Ubiquitin Thiolesterase; C496976:Uchl1 protein, mouse