Scientists at he Institute for Research in Biomedicine (IRB Barcelona) –headed by ICREA researcher Angel R. Nebreda– discover a crucial protein for meiosis, the cell division process that gives rise to sex cells. Without the RingoA protein, both male and female mice are sterile. Published in Nature Communications, the results could pave the way for the development of male contraceptives.

In contrast to the cells in the rest of the body, sex cells hold half the number of chromosomes (they are haploid) as a result of this special kind of cell division. In meiosis, a precursor cell —primordial germ cell— produces four spermatozoids during spermatogenesis, while only one oocyte is formed during oogenesis (the other three cells die during the process).

In this study, scientists has reported that the protein RingoA is a key regulator of meiosis—the cell division process that gives rise to ovules and sperm for sexual reproduction in mammals.

In contrast to the cells in the rest of the body, sex cells hold half the number of chromosomes (they are haploid) as a result of this special kind of cell division. In meiosis, a precursor cell —primordial germ cell— produces four spermatozoids during spermatogenesis, while only one oocyte is formed during oogenesis (the other three cells die during the process).

Mice deficient in RingoA, generated in Nebreda’s Signalling and Cell Cycling Laboratory, are apparently healthy but both sexes are completely sterile. After three years of experiments, IRB Barcelona postdoctoral researchers Petra Mikolcevic and Michitaka Isoda describe the molecular imbalances that occur during meiosis as a result of the absence of this protein.

Amb l’estudi, els investigadors aporten noves dades sobre un procés fonamental per a totes les formes de vida que es reprodueixen sexualment. “Tots vam començar amb una meiosi així que saber com funciona és intel·lectualment molt interessant”, apunta Nebreda. Tot i que la meiosi es va descriure a la fi del segle XIX “queden molts interrogants oberts”, explica aquest científic guardonat amb un projecte de l’European Research Council.

This study sheds new light on a key process for all forms of life that engage in sexual reproduction. “We all start life through meiosis so understanding how this process works is intellectually interesting,” saysNebreda. Although meiosis was first described in the late 19th century, “many questions remain unanswered,” explains this scientist, holder of a European Research Council grant.

“There are no good in vitro models available to study meiosis. It is difficult to extract spermatocytes and to perform studies in plates; they have to be studied in the testicles. And oocytes are even worse because ovules are formed in early stages of development and working with embryos is technically complex.”

• Reference article:

Essential role of the Cdk2 activator RingoA in meiotic telomere tethering to the nuclear envelope. Petra Mikolcevic, Michitaka Isoda, Hiroki Shibuya, Ivan del Barco Barrantes, Ana Igea, José A. Suja, Sue Shackleton, Yoshinori Watanabe & Angel R. Nebreda. Nature Comms. (2016, 30 March). Doi: 10.1038/NCOMMS11084