Mammalian sperm typically enter the vagina by the hordes. Yet, only a few sperm—if any—among 200 million brethren win. To win the fertilization contest, a sperm must be the most forceful swimmer. In a study with implications for human infertility and male contraception, David Clapham and colleagues at Children’s Hospital Boston and HMS discovered a novel protein in mouse sperm called CATSPER delta and its encoding gene, Tmem146, that are essential for sperm motility.

The findings, reported Jan. 11 in Nature Communications, identified CATSPER delta as a new and essential component of the sperm-tail-specific CatSper channel. Clapham, HMS professor of neurobiology and pediatrics and the Aldo R. Castaneda Professor of Cardiovascular Research at Children’s Hospital, and others previously characterized the CatSper channel to be a complex calcium- selective ion channel and showed that calcium currents generated across CatSper channels bring about the whip-like motions of the sperm. This CatSper-induced hyperactivated motility of the sperm is essential for egg penetration. The researchers suggest that CATSPER delta facilitates the assembly and/or transport of the channels to their correct locations in the sperm tail, even if CATSPER delta may not form the inner pore of the CatSper channel per se. As predicted, when CATSPER delta is disrupted, the sperm produced are immobile and the male mice are infertile.

For more information, students may contact David Clapham at dclapham@enders.tch.harvard.edu.

Conflict Disclosure: The authors declare no conflicts of interest.

Funding Sources: This research was supported by the National Institutes of Health; the authors are solely responsible for the content of this work.

Disclaimer: The researchers are unable to provide treatment recommendations for individual cases.