Bipotential semen proteins as sperm-protective and immunosuppressive reagents

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K18164
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Integrative animal science; General medical chemistry
• Research Institution: Meiji University
• Principal Investigator: Kawano Natsuko 明治大学, 農学部, 専任講師 (00451691)
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: 体内受精 / 精液タンパク質 / 自然免疫 / 補体

Outline of Final Research Achievements

Internal fertilization is a complicated process, including gametes and liquid factors from both female and male. We hypothesized competitive factors in the internal fertilization: spermicide in female uterine fluid and sperm-protectant in male semen. These factors seem to be essential for the internal fertilization, but the precise mechanism was still unclear. In this study, we produced Svs2-6-/- male mice for deleting mouse-type semen and human SemgI/II knockin male mice for introducing human-type semen. We suppose the possibility for the humanized male mice with high fertility, which suggests that the seminal plasma proteins across the two species protect sperm from female immunity and development for human immunosuppressive reagents. In female spermicide, we found that uterine complement C3 kills sperm in the absence of SVS2. C3 covered the surface of the killed sperm with unique formation. Our research about the internal fertilization may shed light on the new innate immune system.

Free Research Field

生殖科学

Academic Significance and Societal Importance of the Research Achievements

ヒトの繁殖様式である体内受精には、女性因子と男性因子のバランスで成り立つ複雑さがある。現在の不妊患者のうち、卵や精子には異常が見られない原因不明とされるケースが多数存在する。複雑な体内受精のしくみを少しでも明らかにすることで、不妊原因の究明および、より自然な妊娠を可能にする治療法の開発が可能になると考えている。本研究では、男性の精液タンパク質に異常がある場合は精子形成が正常でも子宮内で精子が死滅すると予想され、女性の免疫力が亢進している場合は過剰に精子が排除されていると予想される。それぞれのしくみを詳細に知ることが、受精率の高い体内受精とはどういう状態のことを意味するのか理解したい。