A team of researchers have discovered a how a specific protein that determines the length of a sperm’s tail significantly effects male fertility.

 

The team, from Monash University, the University of Newcastle, John Curtin School of Medical Research, Garvan Institute of Medical Research and the University of Cambridge discovered how the RABL2 protein affects the length of sperm tails, determining their motility and sperm production.

 

Professor Moira O’Bryan from Monash University led the research that found that a mutation in RABL2 resulted in sperm tails that were 17 per cent shorter than normal. The research also showed that dysfunctional RABL2 also negatively affected sperm production, resulting in a 50 per cent decrease.

 

"The mutations in the RABL2 gene are very likely to cause infertility," Professor O'Bryan said.


"Further, as motility is absolutely essential for fertility, insights into tail function may reveal options for urgently needed male-based contraception." 

 

Lead author and PhD student Jennifer Lo, also from the School of Biomedical Sciences, said RABL2 worked with other molecules known as intraflagellar transport proteins that carry genetic cargo along the sperm tail.


"Intraflagellar transport proteins are like a train. Our data suggests that the reloading of the train is defective if RABL2 dysfunctions,” Ms Lo said.


“The train is still running in sperm tails with dysfunctional RABL2, but it contains fewer passengers. The end result is that sperm formation and motility are abnormal.”


Ms Lo said that as mutations in RABL2 decrease sperm count and sperm swimming ability, it may be possible to inhibit this protein in a future male pill.


However, as RABL2 is also found, albeit in lower concentrations, in other tissues, such as the brain, kidney and liver, an inhibitor specific to the testes would need to be developed.