Browsing by Author "Kim, Young-Hyun"

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    Hyaluronidase 6 Does Not Affect Cumulus-Oocyte Complex Dispersal and Male Mice Fertility
    (MDPI, 2022-04-25) Bang, Hyewon; Lee, Sujin; Jeong, Pil-Soo; Seol, Dong-Won; Son, Daeun; Kim, Young-Hyun; Song, Bong-Seok; Sim, Bo-Woong; Park, Soojin; Lee, Dong-Mok; Wee, Gabbine; Park, Joon-Suk; Kim, Sun-Uk; Kim, Ekyune; Biochemistry and Molecular Biology, School of Medicine
    Glycosylphosphatidylinositol-anchored sperm hyaluronidases (HYAL) assist sperm penetration through the cumulus-oocyte complex (COC), but their role in mammalian fertilization remains unclear. Previously, we demonstrated that sperm from HYAL 5 and 7 double-knockout (dKO) mice produced significantly less offspring than sperm from wild-type mice due to defective COC dispersal. However, the HYAL6 gene remained active in the sperm from the dKO mice, indicating that they were not entirely infertile. This study explored the role of HYAL6 in fertilization by analyzing HYAL6-mutant mice. In this mouse model, HYAL5 and HYAL7 were present in the HYAL6-knockout sperm, and they could disperse hyaluronic acid. We found that HYAL6 was present on the surface of sperm. However, male mice lacking the HYAL6 gene had normal fertility, testicular integrity, and sperm characteristics. Furthermore, in vitro fertilization assays demonstrated that HYAL6-deficient epididymal sperm functioned normally. Therefore, HYAL6 is dispensable for fertilization.
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    Sperm hyaluronidase is critical to mammals' fertilization for its ability to disperse cumulus-oocyte complex layer
    (Wolters Kluwer, 2022) Seol, Dong-Won; Joo, Sang Hoon; Kim, Young-Hyun; Song, Bong-Seok; Sim, Bo-Woong; Kim, Sun-Uk; Park, Soojin; Wee, Gabbine; Kim, Ekyune; Biochemistry and Molecular Biology, School of Medicine
    Glycosylphosphatidylinositol-anchored sperm hyaluronidases have long been believed to assist in sperm penetration through the cumulus-oocyte complex (COC); however, their role in mammalian fertilization remains unclear. Previously, we have shown that hyaluronidase 5 (Hyal5)/Hyal7 double-knockout (dKO) mice produce significantly fewer offspring than their wild-type (WT) counterparts because of defective COC dispersal. Male infertility is mainly caused by a low sperm count. It can be further exacerbated by the deficiency of sperm hyaluronidase, which disperses the cumulus cells of the outer layer of the COC. In the current study, we evaluated the effects of a low count of Hyal-deficient sperm and conditions of ovulated oocytes on the fertilization rate using a mouse model. Our results demonstrated that a low sperm count further decreases the in vitro fertilization (IVF) rate of Hyal-deficient dKO spermatozoa. In addition, the dKO spermatozoa resulted in a fertilization rate of 12.5% upon fertilizing COCs with a thick cumulus layer, whereas the IVF rate was comparable to that of WT spermatozoa when oocytes with a thin or no cumulus layer were fertilized. Finally, we proved that the IVF rate of dKO spermatozoa could be recovered by adding rat spermatozoa as a source of sperm hyal. Our results suggest that a deficiency of proteins involved in fertilization, such as sperm hyal, has a vital role in fertilization.