Assessing the Relationship between proAKAP4 Level and Longevity of Sexed Sperm Quality after Thawing

ProAKAP4 is a sperm structural protein that regulates motility through the PKA-dependent cAMP signaling pathway, which is synthesized as an X chromosome-linked member of the gene family. This study aims to determine the optimal level of proAKAP4 for evaluating sexed semen through investigating its relationship with the longevity of sperm quality in sexed Holstein bull sperm. A total of 30 sexed sperm samples (bearing X chromosomes) from 30 distinct Holstein bulls (n = 30) were analyzed. The frozen bull sperm samples were assessed for their proAKAP4 levels, mitochondrial membrane potential, plasma membrane and acrosome integrity (PMAI), and spermatozoa movement parameters at hours 0 and 3 after thawing. The proAKAP4 levels in the sexed sperm samples ranged from 16.35 to 72.10 ng/10 M spz, with an average of 37.18 ± 15.1 ng/10 M spz. A strong positive correlation was observed between proAKAP4 levels and total motility, progressive motility, PMAI, high mitochondrial membrane potential, VAP, and VCL values after 3 h of incubation, when compared to post-thaw analyses. The results also reveal that spermatozoa with proAKAP4 levels of ≥40 ng/10 M spz exhibit higher quality. In conclusion, the level of proAKAP4 in sexed sperm aligns with previous studies and shows potential as a biomarker for assessing the longevity of sexed sperm quality.