182. ROLE OF CRISP4 IN ION CHANNEL REGULATION AND MALE REPRODUCTION

Abstract

CRISPs are a group of 3 proteins found in mammals (4 in the mouse) which show a strong expression bias in the male reproductive organs. Whilst the function of most CRISPs are yet to be elucidated, mouse CRISP2 is a known regulator of the ion channel, ryanodine receptor. CRISP4 is most abundantly produced by the principal cells of the epididymis and are secreted into the lumen, where they adhere to sperm during epididymal transit. In this study we examined the role of CRISP4 ion channel regulation in mouse spermatozoa through cell assays and mouse models. The identification of the Transient Receptor Potential (TRP) ion channel, TRPM8 to interact with CRISP4 was confirmed using stably-transfected CHO cell lines. Production of CRISP4 KO mouse model, whilst males are fertile, they exhibit a subtle infertility phenotype characterized by a reduced ability to capacitate and undergo the acrosome reaction. This data is further emphasized by the ability of TRPM8 agonists, icillin and menthol, to inhibit the acrosome reaction in mouse spermatozoa that could be prevented by the addition of recombinant CRISP4 crisp domain. Corresponding to these data, CRISP4 is localized to the tail and head of mouse spermatozoa. In conclusion, we have demonstrated that CRISP4 is a regulator of TRPM8 in mouse spermatozoa, and due to its expression and localization pattern is an important protein in sperm epididymal maturation.