O-039 Novel sperm centrosome function, structure, and composition during fertilization

Abstract

Abstract Sperm centrioles play a critical role in sperm differentiation and embryo development, and they are implicated in infertility and miscarriages. However, the precise way centrioles function and are inherited during fertilization in mammals remains unresolved. A key reason for this lack of understanding is that many proteins are only transiently present in the sperm centriole because of a process known as Centrosome Reduction and that sperm centrioles exhibit dramatic species-specific adaptions. It was long widely accepted that structural degeneration and functional inactivation occur at one or two of the centrioles in mammals, resulting in a vestigial remnant. This led to the belief that human spermatozoa have only one functional centriole (the Proximal Centriole, PC). While Centrosome Reduction happens in mice, our studies suggest that two centrioles are present, and both are essential in non-murine mammals. However, the Distal Centriole (DC) has a highly atypical structure and composition, while the PC is only modestly modified. These findings led us to a new model: Centriole Remodeling, which states that preexisting spermatid centrioles, along with their pericentriolar material (PCM), go through a structural and compositional transformation during differentiation resulting in remodeled centrioles and PCM that functions as a dynamic basal complex (DBC) in the spermatozoon and as a precursor for the embryonic centrioles. A crucial mystery remaining is: what are the centrioles' essential functions? To answer this question, we study the sperm centrioles' function and remodeling process in infertile men and rabbit mutants with partially disabled sperm centrioles. Trial registration number -