P-082 The functional role of Acrv1 in sperm-egg binding
C Dai, H Wu, G LinAbstract
Study question
What is the functional role of the sperm acrosomal vesicle protein 1 (Acrv1) in mammalian fertilization?
Summary answer
The sperm acrosomal protein Acrv1 plays a crucial role in sperm-egg binding, primarily by participating in the acrosome reaction and traversing the zona pellucida.
What is known already
Fertilization in mammals refers to a process wherein male sperm meets and combines with female egg, marking the beginning of a new life. Fertilization failure occurs when sperm cannot penetrate the zona pellucida or the oolemma. The acrosome, situated at the anterior pole of the sperm head, plays a crucial role in mediating sperm-egg binding. Acrv1 is a sperm intra-acrosomal protein, specific to the testis, that has been detected in several species including humans. Recombinant protein and functional assays indicated that Acrv1 is associated with acrosomal reaction and sperm-egg interactions, little is yet known of its role in fertilization.
Study design, size, duration
This study aims to elucidate the role and mechanism of the Acrv1 in sperm-egg binding and fertilization by generating Acrv1 knockout mice, thereby providing insights into the function and interrelationships of acrosomal proteins during fertilization.
Participants/materials, setting, methods
The Acrv1 knockout mice was generated by CRISPR/Cas9 technology.Fertility assessment was performed by cohabitation of mature male and female mice. Employing testicular histological staining, spermatozoa staining, and Computer-aided sperm analysis system (CASA), we analyzed the effects of Acrv1 on acrosome formation, the morphology and motility of ejaculated sperm. Furthermore, we assessed the effects of Acrv1 on the acrosome reaction and fertilization capacity in vitro.
Main results and the role of chance
The Acrv1-/- mouse model was successfully established, and fertility assessment along with in vitro fertilization experiments indicated a decreased fertility capacity in Acrv1-/- male mice, attributable to defects in sperm penetration through the zona pellucida leading to diminished capability for in vitro fertilization. A significantly accelerated spontaneous and progesterone-induced acrosome reaction in vitro were observed in Acrv1-/- spermatozoa. HE and IF staining of testicular and epididymal sections revealed that the absence of Acrv1 protein did not affect spermatogenesis but impeded early vesicle fusion during acrosome formation, attachment of the acrosomal cap to the acroplaxome, and the morphology of matured acrosomes. Furthermore, the “ Manchette” as a crucial cytoskeletal and protein transport structure during sperm deformation, exhibited significant elongation and delayed depolymerization in the late stages of Acrv1-/- sperm formation. Papanicolaou Stain and CASA results demonstrated that the absence of Acrv1 protein did not significantly affect the morphology and two-dimensional motility of ejaculated sperm.
Limitations, reasons for caution
The phenomena observed in our Acrv1-/- mouse model require further research to uncover the underlying molecular mechanisms.
Wider implications of the findings
The sperm acrosomal protein Acrv1 plays a crucial role in sperm-egg binding, primarily by participating in the acrosome reaction and traversing the zona pellucida. Our study has deepened the understanding of Acrv1 function and provided more evidences to confirm that ACRV1 is involved in sperm-egg binding and fertilization.
Trial registration number
No