Journal article
An oocyte-specific astacin family protease, alveolin, is released from cortical granules to trigger egg envelope hardening during fertilization in medaka (Oryzias latipes)
Developmental biology, Vol.372(2), pp.239-248
12/15/2012
Handle:
https://hdl.handle.net/2376/116528
PMID: 23022660
Abstract
It has long been hypothesized that in fishes the contents of cortical granules are involved in the hardening of egg envelope following fertilization. We previously purified the egg envelope hardening initiation factor from the exudates released from activated medaka (Oryzias latipes) eggs and tentatively termed this protein alveolin. Alveolin is a member of the astacin metalloprotease family and was proposed to be a protease which hydrolyzes ZPB at one restricted position to allow starting cross-linking with ZPC. Here, we investigated the complete pathway from biosynthesis and accumulation to secretion of alveolin. A single alveolin transcript was detected only in ovarian preparations, confirming the specific expression of alveolin in the ovary. In situ hybridization indicated that the alveolin mRNA is already expressed in the very early previtellogenic oocytes. However, immunocytochemical studies revealed that the appearance of alveolin protein was delayed until the beginning of the vitellogenic stage. The cortical granules isolated from unfertilized eggs contained a high molecular weight form of glycosylated alveolin with a 50kDa relative molecular mass. Hypotonic treatment burst isolated granules in vitro and transformed alveolin to a 21.5kDa form, which is the same size as that of natural alveolin released from eggs upon fertilization. This transformation was inhibited in the presence of leupeptin and 4-(2-aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF), suggesting that a serine protease is involved in alveolin activation upon fertilization. Furthermore, the phylogenetic relationship of alveolin with other vertebrate astacin family members was analyzed. The result shows that alveolin and its teleostean homologs make a new group which is separate from either the hatching enzyme, meprin and BMP1/tolloid groups.
► Alveolin is an oocyte-specific astacin family protease of medaka fish. ► Alveolin and its homologs form a group within the vertebrate ascatin family. ► The cortical granules of oocytes store a latent form of alveolin. ► Activation of alveolin occurs during exocytosis upon fertilization.
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Details
- Title
- An oocyte-specific astacin family protease, alveolin, is released from cortical granules to trigger egg envelope hardening during fertilization in medaka (Oryzias latipes)
- Creators
- Yasushi Shibata - Laboratory of Reproductive Biology, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, JapanTakashi Iwamatsu - Department of Biology, Aichi University of Education, Kariya, Aichi 448-8542, JapanNorio Suzuki - Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, JapanGraham Young - School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, USAKiyoshi Naruse - Laboratory of BioResource, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, JapanYoshitaka Nagahama - Laboratory of Reproductive Biology, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, JapanMichiyasu Yoshikuni - Laboratory of Reproductive Biology, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Publication Details
- Developmental biology, Vol.372(2), pp.239-248
- Academic Unit
- UNKNOWN
- Publisher
- Elsevier Inc
- Identifiers
- 99900547663601842
- Language
- English
- Resource Type
- Journal article