Testis‐specific proteins, TSNAXIP1 and 1700010I14RIK, are important for sperm motility and male fertility in mice

Abstract Background TSN (translin), also called testis brain RNA‐binding protein, binds to TSNAX (translin‐associated factor X) and is suggested to play diverse roles, such as RNA metabolism and DNA damage response. TSNAXIP1 (Translin‐associated factor X‐interacting protein 1) was identified as a TSNAX‐interacting protein using a yeast two‐hybrid system, but its function in vivo was unknown. Objective To reveal the function of TSNAXIP1 in vivo in mice. Materials and methods We generated Tsnaxip1 knockout mice using the CRISPR/Cas9 system and analyzed their fertility and sperm motility. Further, we generated 1700010I14Rik knockout mice, because 1700010I14RIK is also predominantly expressed in testes and contains the same Pfam (protein families) domain as TSNAXIP1. Results Reduced male fertility and impaired sperm motility with asymmetric flagellar waveforms were observed in not only Tsnaxip1 but also 1700010I14Rik knockout mice. Unlike Tsn knockout mice, no abnormalities were found in testicular sections of either Tsnaxip1 or 1700010I14Rik knockout mice. Furthermore, TSNAXIP1 was detected in the sperm tail and fractionated with axonemal proteins. Discussion and conclusion Unlike the TSN–TSNAX complex, whose disruption causes abnormal vacuoles in mouse testes, TSNAXIP1 and 1700010I14RIK may play roles in regulating sperm flagellar beating patterns.