Testicular stage- and cell-specific expression of F-actin-binding proteins

Sertoli cells are essential to successful, continuous sperm production and are responsible for many processes throughout spermatogenesis, including germ cell movement and compartmentalization of the seminiferous tubule interior. These functions due to the F-actin cytoskeleton present within the seminiferous tubules, which facilitates cell movement and adhesion. While some molecular players that regulate the testicular F-actin cytoskeleton are known, the expression of other actin-related genes in the mammalian testis remains unknown. In this study, we revisited previously published next-generation sequencing data and combined this with immunohistochemical analysis to identify the cell- and stage-specific expression of multiple alpha-actinin and myosin genes and their protein products. This work provides the first characterization of alpha-actinin and myosin localization within murine testes throughout spermatogenesis. We identified alpha-actinin-3, alpha-actinin-4, myosin VIIa (MYO7A), and myosin 10 as potential functional candidates regulating cytoskeleton dynamics throughout spermatogenesis based on the high mRNA expression of these genes observed within Sertoli cells, as well as the specific protein localization observed within Sertoli cells. We additionally found expression of MYO7A within early spermatogonia and meiotic germ cells, suggesting a potential role of these proteins during mitotic and meiotic division. Overall, this study provides insight into the expression of many F-actin-related genes during mammalian testicular maturation and contributes to our understanding of dynamic Sertoli cell gene expression in mammalian testes.