The research team Kogiku Shiba and Kazuo Inaba at the University of Tsukuba in collaboration with the Osaka University found sperm calcineurin (PPP3CC/PPP3R2), phosphatase expressed in a testis , as an essential enzyme to regulate the normal mobility and fertilization ability of sperms. A sperm without calcineurin can not make a turn because the middle part of the tail does not move. As a result, it cannot show normal mobility to be fertilized to an egg.

Calcineurin is widely known as phosphatase that can be found in all over the body. Moreover, the research team investigated the mechanism of male sterility in mouse in a condition of distracted genome regarding sperm calcineurin that specifically expressed in a testis. Male human body also has sperm calcineurin in the testis along with the activity of the phosphatase. Besides, the team confirmed the function of sperm calcineurin; calcineurin inhibitor application in two weeks to a male mouse induced sterility, and if the application stopped, reproductive ability recovers in a week.

A drug research and discovery field has not invented oral contraceptives for male yet. If a medication could specifically inhibit sperm calcineurin, researchers would be expected to develop a quick and reversible oral contraceptives for man. Moreover, the new finding of the mechanism in regards to sperm mobility function would add new perspectives to understanding results of sterility and diagnosis on it.

Spermatozoa motility.
A: Flagellar bending pattern of mouse spermatozoa with calcineurin. B: The midpiece (black arrow) was inflexible in the spermatozoa without calcineurin. C: The spermatozoa without calcineurin cannot penetrate the sperm zona pellucida (black arrow).

Original Paper

Haruhiko Miyata, Yuhkoh Satouh, Daisuke Mashiko, Masanaga Muto, Kaori Nozawa, Kogiku Shiba, Yoshitaka Fujihara, Ayako Isotani, Kazuo Inaba, and Masahito Ikawa, Science, Sperm calcineurin inhibition prevents mouse fertility with implications for male contraception. DOI: 10.1126/science.aad0836