Endocrinology 2016 Oct 4;157(10):3719-3730. Epub 2016 Aug 4.
Department of Physiology and Turku Center for Disease Modeling (H.K., M.A., J.M.-J., T.D.L., L.S., M.P.), Institute of Biomedicine, University of Turku, FI-20540 Turku, Finland; Department of Clinical Science, Intervention and Technology (P.D., O.H.), Karolinska Institute, 141 52 Huddinge, Sweden; Swedish Toxicology Sciences Research Center (P.D.), Karolinska Institutet, 141 86 Stockholm, Sweden; Department of Biosciences and Nutrition (A.E.D., J.K.), Karolinska Institutet, 171 77 Stockholm, Sweden; Department of Mathematics and Statistics (T.D.L., T.A.), University of Turku, FI-20014 Turku, Finland; Institute for Molecular Medicine Finland (T.A.), University of Helsinki, FI-00014 Helsinki, Finland; Experimental Genetics (J.A.), Center of Life and Food Sciences, Weihenstephan, 85354 Freising, Germany; Institute of experimental Genetics (J.A.), Helmholtz Zentrum, 81377 München, Germany; Genome Analysis Center (J.A.), German Research Center for Environmental Health, 85764 Neuherberg, Germany; Institute of Neuroscience and Physiology (H.R.), Sahlgrenska Academy, University of Gothenburg, SE-405 30 Gothenburg, Sweden; Institute of Medicine (C.O., M.P.), The Sahlgrenska Academy, University of Gothenburg, SE-413 46 Gothenburg, Sweden.
The hydroxysteroid (17beta) dehydrogenase (HSD17B)12 gene belongs to the hydroxysteroid (17β) dehydrogenase superfamily, and it has been implicated in the conversion of estrone to estradiol as well as in the synthesis of arachidonic acid (AA). AA is a precursor of prostaglandins, which are involved in the regulation of female reproduction, prompting us to study the role of HSD17B12 enzyme in the ovarian function. We found a broad expression of HSD17B12 enzyme in both human and mouse ovaries. The enzyme was localized in the theca interna, corpus luteum, granulosa cells, oocytes, and surface epithelium. Interestingly, haploinsufficiency of the HSD17B12 gene in female mice resulted in subfertility, indicating an important role for HSD17B12 enzyme in the ovarian function. In line with significantly increased length of the diestrous phase, the HSD17B females gave birth less frequently than wild-type females, and the litter size of HSD17B12 females was significantly reduced. Interestingly, we observed meiotic spindle formation in immature follicles, suggesting defective meiotic arrest in HSD17B12 ovaries. The finding was further supported by transcriptome analysis showing differential expression of several genes related to the meiosis. In addition, polyovular follicles and oocytes trapped inside the corpus luteum were observed, indicating a failure in the oogenesis and ovulation, respectively. Intraovarian concentrations of steroid hormones were normal in HSD17B12 females, whereas the levels of AA and its metabolites (6-keto prostaglandin F1alpha, prostaglandin D, prostaglandin E, prostaglandin F, and thromboxane B) were decreased. In conclusion, our study demonstrates that HSD17B12 enzyme plays an important role in female fertility through its role in AA metabolism.