Testis-enriched Asb12 is not required for spermatogenesis and fertility in mice

Background: Members of the ankyrin repeat and SOCS box (Asb) family are expressed abundantly in testes. Some Asb genes/proteins are required for spermatogenesis, but the function of Asb12 during spermatogenesis is not clear. We investigated the physiological role of Asb12 in murine testes.

Methods: The clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 system was used to generate Asb12-knockout (KO) mice. Histology and immunostaining were done to assess the effects of Asb12 KO on mouse testes and epididymides. Semen quality was analyzed using a computer-assisted sperm analyzer. The terminal deoxynucleotidyl transferase-dUTP nick-end labeling assay was employed to examine testicular apoptosis. Real-time reverse transcription-quantitative polymerase chain reaction (PCR) was conducted to calculate gene transcription levels.

Results: Asb12 was expressed predominantly in murine testes. Immunostaining of Asb12 protein revealed that Asb12 was located specifically in the acrosome of elongated spermatids, which suggested a potential role of Asb12 during spermatogenesis. However, Asb12-KO mice had normal fertility, and no overt difference was detected in testicular morphology, semen quality, or apoptosis when comparing Asb12-KO and Asb12-wild type (WT) mice. Gene expression of several Asb family members was increased significantly in the testes of Asb12-KO mice when compared with that in Asb12-WT mice, which suggested functional compensation from paralogs for Asb12 loss.

Conclusions: We demonstrated that Asb12 is not essential for the spermatogenesis and fertility of mice. Our findings will assist researchers in avoiding redundant efforts, and provide a baseline resource for genetic studies on human fertility.