title: 17β-HSD Type 12-Like Is Responsible for Maturation-Inducing Hormone Synthesis During Oocyte Maturation in Masu Salmon.
abstract: The maturation-inducing hormone 17α,20β-dihydroxy-4-pregnen-3-one (DHP) was first identified in the amago salmon. Although carbonyl reductase-like 20β-hydroxysteroid dehydrogenase (CR/20β-HSD) was reported to convert 17α-hydroxyprogesterone (17OHP) to DHP in rainbow trout, we previously found that CR/20β-HSD messenger RNA (mRNA) was not upregulated in stimulated granulosa cells from masu salmon, which suggested that DHP is synthesized by a different enzyme. Accordingly, the current study aimed to identify the specific 20β-hydroxysteroid dehydrogenase (20β-HSD) responsible for DHP production by granulosa cells during final oocyte maturation in masu salmon. RNA sequencing was performed on granulosa layers that were isolated from ovarian follicles at 1 month before ovulation and incubated with or without forskolin, which was used to mimic luteinizing hormone, and ∼12 million reads were obtained, which yielded 71,062 contigs of >100 bp. tBlastx analysis identified 1 contig (#f103496) as similar to 17β-hydroxysteroid dehydrogenase type 12 (hsd17β12); however, because the full-length #f103496 sequence was different from hsd17β12, it was termed hsd17β12-like (hsd17β12l). We found that mammalian cells transfected with full-length hsd17β12l exhibited considerable 20β-HSD activity, as indicated by efficient conversion of exogenous 17OHP to DHP. In addition, we found that hsd17β12l mRNA levels were consistently low in follicles during vitellogenic growth; however, the levels increased significantly during final oocyte maturation. The levels of hsd17β12l mRNA were also considerably increased in granulosa layers in which 20β-HSD activity was induced by salmon pituitary extract. Therefore, we suggest that hsd17β12l, not CR/20β-HSD, is the 20β-HSD responsible for DHP production by granulosa cells in masu salmon during final oocyte maturation.
authors.affiliation: Division of Marine Life Sciences, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Shigeho
authors.initials: S
authors.lastname: Ijiri
authors.affiliation: School of Aquatic and Fishery Science, University of Washington, Seattle, Washington.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shibata
authors.affiliation: Division of Marine Life Sciences, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Nonoha
authors.initials: N
authors.lastname: Takezawa
authors.affiliation: National Research Institute of Aquaculture, Fisheries Research Agency, Watarai, Mie, Japan.
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Kazeto
authors.affiliation: Division of Marine Life Sciences, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Takatsuka
authors.affiliation: Division of Marine Life Sciences, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Erika
authors.initials: E
authors.lastname: Kato
authors.affiliation: Division of Marine Life Sciences, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Seishi
authors.initials: S
authors.lastname: Hagihara
authors.affiliation: National Research Institute of Aquaculture, Fisheries Research Agency, Watarai, Mie, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ozaki
authors.affiliation: Division of Marine Life Sciences, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Adachi
authors.affiliation: South Ehime Fisheries Research Center, Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Yamauchi
authors.affiliation: South Ehime Fisheries Research Center, Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nagahama
mesh_terms: D015067:17-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D005260:Female; D029941:Fish Proteins / Q000378:metabolism*; D006107:Granulosa Cells / Q000378:metabolism; D006908:Hydroxyprogesterones / Q000378:metabolism*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000254:growth & development*; D012474:Salmon; D012621:Seasons; D017423:Sequence Analysis, RNA
chemical_list: D029941:Fish Proteins; D006908:Hydroxyprogesterones; C007433:17,20-dihydroxy-4-pregnen-3-one; D015067:17-Hydroxysteroid Dehydrogenases