10.08.2022: The sperm protein proAKAP4 has been proposed as a marker of sperm quality and male fertility in many animal species. A recently published study from the University of Veterinary Medicine Vienna has for the first time investigated the relationship between proAKAP4 levels and sperm motility following cryopreservation in laboratory mice, finding no difference between fresh and frozen-thawed samples. The exact role of proAKAP4 as a marker of sperm quality, however, remains controversial. The findings of the study may also help to reduce the number of animals required in animal experiments.

Sperm are highly specialised cells with a single task: to transport the male genome to the egg and fertilise it. The scaffold protein AKAP4 plays a crucial role in sperm motility, and its precursor proAKAP4 has for several years been suggested as a marker of male fertility. In a recently published study, a team from the Institute of in vivo and in vitro Models at Vetmeduni determined the relationship between proAKAP4 concentration and sperm motility parameters in mice and investigated how freezing the sperm (cryopreservation) affects these two variables. The scientists analysed sperm samples from several mouse strains using computer-assisted sperm analysis and enzyme-linked immunosorbent assay (ELISA), a technique to detect antibodies in biological samples.

ProAKAP4 as a marker for fertility

Fertility markers are needed to select the potentially best animals for breeding and to exclude animals with poor fertility from the outset. “We found a negative relationship between proAKAP4 levels and sperm motility parameters. This came as a surprise, as previous studies had reported a positive relationship in other animal species. In a follow-up study, we are now investigating whether proAKAP4 levels have an effect on the fertilisation success of sperm in in vitro fertilisation,” says first author Auke Boersma from the Institute of in vivo and in vitro Models at Vetmeduni at the Department of Biomedical Sciences at Vetmeduni.

No influence of cryopreservation on proAKAP4

ProAKAP4 levels in epididymal sperm samples were unaffected by cryopreservation, demonstrating the value of proAKAP4 as a potentially time-independent marker for sperm motility and fertility. “The high individual variation in proAKAP4 levels also supports the potential role of proAKAP4 as a marker for sperm quality,” as last author Kerstin E. Auer, also from the Institute of in vivo and in vitro Models at Vetmeduni, explains.

Findings help lower number of animals in experiments

Laboratory mice are the most important model organism for studying human diseases. Mice share 99% of their genes with humans, and their study with modern genetic modification techniques remains indispensable in the search for therapies for incurable diseases. The generation of these disease models mainly relies on reproductive techniques such as embryo transfer, sperm or embryo cryopreservation and in vitro fertilisation. A deeper understanding of the processes underlying male fertility and in particular sperm function will further improve the efficiency of these techniques. The researchers expect that these findings will lower the number of animals required, which is in line with the principles of 3R to replace, reduce and refine animal experiments.

The article “Influence of sperm cryopreservation on sperm motility and proAKAP4 concentration in mice” by Auke Boersma, Jasmin Primus, Bettina Wagner, Veronika Broukal, Lill Andersen, Barbara Pachner, Maik Dahlhoff, Thomas Rülicke and Kerstin E. Auer was published in Reproductive Medicine and Biology.
 

Scientific article