- 著者
- Ijiri Shigeho Shibata Yasushi Takezawa Nonoha Kazeto Yukinori Takatsuka Naoki Kato Erika Hagihara Seishi Ozaki Yuichi Adachi Shinji Yamauchi Kohei Nagahama Yoshitaka
- 出版者
- Endocrine Society
- 雑誌
- Endocrinology (ISSN:00137227)
- 巻号頁・発行日
- vol.158, no.3, pp.627-639, 2017-03
- 被引用文献数
- 3
The maturation-inducing hormone 17(alpha), 20(beta)-dihydroxy-4-pregnen-3-one (DHP) was first identified in the amago salmon. Although carbonyl reductase-like 20 beta-hydroxysteroid dehydrogenase (CR/20b-HSD) was reported to convert 17 alpha-hydroxyprogesterone (17OHP) to DHP in rainbow trout, we previously found that CR/20 beta-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 20 beta-hydroxysteroid dehydrogenase (20 beta-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 similar to 12 million reads were obtained, which yielded 71,062 contigs of > 100 bp. tBlastx analysis identified 1 contig (#f103496)as similar to 17 beta-hydroxysteroid dehydrogenase type 12 (hsd17 beta 12); however, because the full-length #f103496 sequence was different from hsd17 beta 12, it was termed hsd17 beta 12-like (hsd17 beta 12l). We found that mammalian cells transfected with full-length hsd171 beta 2l exhibited considerable 20b-HSD activity, as indicated by efficient conversion of exogenous 17OHP to DHP. In addition, we found that hsd17 beta 12l mRNA levels were consistently low in follicles during vitellogenic growth; however, the levels increased significantly during final oocytematuration. The levels of hsd17 beta 12lmRNA were also considerably increased in granulosa layers in which 20 beta-HSD activity was induced by salmon pituitary extract. Therefore, we suggest that hsd17 beta 12l, not CR/20 beta-HSD, is the 20 beta-HSD responsible for DHP production by granulosa cells in masu salmon during final oocytematuration.
- 著者
- Nomoto Hiroshi Kondo Takuma Miyoshi Hideaki Nakamura Akinobu Hida Yoko Yamashita Ken-ichiro Sharma Arun J. Atsumi Tatsuya
- 出版者
- Endocrine Society
- 雑誌
- Endocrinology (ISSN:00137227)
- 巻号頁・発行日
- vol.156, no.10, pp.3570-3580, 2015-10
- 被引用文献数
- 13
The large-Maf transcription factor v-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MafA) has been found to be crucial for insulin transcription and synthesis and for pancreatic beta-cell function and maturation. However, insights about the effects of small Maf factors on beta-cells are limited. Our goal was to elucidate the function of small-Maf factors on beta-cells using an animal model of endogenous small-Maf dysfunction. Transgenic (Tg) mice with beta-cell-specific expression of dominant-negative MafK (DN-MafK) experiments, which can suppress the function of all endogenous small-Mafs, were fed a high-fat diet, and their in vivo phenotypes were evaluated. Phenotypic analysis, glucose tolerance tests, morphologic examination of beta-cells, and islet experiments were performed. DN-MafK-expressed MIN6 cells were also used for in vitro analysis. The results showed that DN-MafK expression inhibited endogenous small-Maf binding to insulin promoter while increasing MafA binding. DN-MafK Tg mice under high-fat diet conditions showed improved glucose metabolism compared with control mice via incremental insulin secretion, without causing changes in insulin sensitivity or MafA expression. Moreover, up-regulation of insulin and glucokinase gene expression was observed both in vivo and in vitro under DN-MafK expression. We concluded that endogenous small-Maf factors negatively regulates beta-cell function by competing for MafA binding, and thus, the inhibition of small-Maf activity can improve beta-cell function.