Structure-function relationships in mammalian spermatozoa; electron- microscopic/biochemical characterization of the male reproductive tract.
Our research focuses on two developmental processes, mammalian spermiogenesis and post-testicular sperm development in the epididymis, which are required to produce motile spermatozoa that can fertilize the egg. We have recently demonstrated that selenoprotein P (Sepp1), a selenium-rich serum protein produced by the liver, is required for male fertility and that Sepp1 null males are infertile and exhibit a specific set of sperm defects. We hypothesize that Sepp1 functions as a delivery protein that provides germ cells with the selenium required for synthesis of their unique complement of selenoproteins. One objective of our current research is define the trafficking pathway by which Sepp1 delivers its selenium content to developing spermatids and to identify critical testis-specific steps in the pathway that may be potential targets for fertility regulation in the male.
Our second major area of research is focused on identifying the mechanims by which the epididymis promotes the viability of stored spermatozoa. Recently we identified a novel high molecular weight glycoprotein, which is a fibrinogen-related protein, that is secreted by the epididymal epithelium and specifically binds to and then polymerizes into a cocoon-like complex coating defective spermatozoa. We are currently focused on defining the molecular aspects of this sperm quality control pathway, to identify its mechanism of binding to defective spermatozoa and to assess if it prevents them from releasing hydrolases or autoantigens that could result in male infertility.