During spermatogenesis, developing germ cells must traverse from the basal lamina to the adluminal compartment of the seminiferous epithelium where fully developed spermatids (spermatozoa) can be released into the tubular lumen. The specialized junctions between Sertoli cells as well as between Sertoli and germ cells must be continuously disrupted, regenerated and/or replaced. Thus, proteases, protease inhibitors, and junctional complex (JC) components are involved in these events. However, the likely sequence of events involving these molecules at different stages of the spermatogenic cycle is not known. During the past two grant periods, this laboratory has demonstrated Sertoli and germ cells behind the blood- testis barrier release multiple proteins that are likely to be involved in germ cell migration. More important, germ cells have been shown to release several molecules having multiple biological activities suggesting they play an active role in their migration. One of these molecules, designated germease, a 41 kDa testicular protein with a unique partial N-terminal amino acid sequence, has been purified from germ cell-conditioned medium (GCCM) during the past grant period. Germease is likely to play a critical role in germ cell migration since was shown to possess two distinctive biological functions. First, it is a Sertoki cell modulator by inhibiting the production of testin, a junctional complex component; and clusterin, a molecule that can induce cell aggregation. Thus, both molecules are involved in cellular association tin the testis. Second, germease is a protease capable of hydrolyzing components of extracellular matrix such as collagen. The primary action of germease was shown to be concentration dependent. During this new grant period, the P.I. will examine the physiological role of germease in the testis and will also characterize its biological action. In addition, the P.I. proposes to use germease and selected proteases, protease inhibitors, and JC components identified in this and other laboratories as markers to construct the cascade of events at different sages of the spermatogenic cycle leading to germ cell migration by in situ hybridization in conjunction with Northern blot analysis. Such a composite picture involving these molecules leading to germ cell migration will be useful in identifying target(s) of intervention to disrupt spermatogenesis which may become a new approach for male contraceptive development.
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