DIFFERENTIAL EXPRESSION OF MULTIPLE CATHEPSIN MESSENGER-RNAS IN THE RAT TESTIS DURING MATURATION AND FOLLOWING LONIDAMINE INDUCED TISSUE RESTRUCTURING

In the seminiferous epithelium, germ cell development behind the blood -testis barrier involves continual degradation and renewal of inter-te sticular cell junctions. This allows: (i) the translocation of develop ing germ cells from the basal lamina to the adluminal compartment duri ng spermatogenesis, and (ii) the eventual release of mature spermatids into the tubular lumen during spermiation. Throughout spermatogenesis , cellular debris must also be removed from the epithelium. Thus, it i s conceivable that proteases, protease inhibitors, and cell junctional components are involved in these events. The present study sought to examine whether testicular cells can express multiple cathepsin mRNAs given that these proteases are involved in the degradation and process ing of proteins as well as in tissue regeneration. By using total RNA isolated from primary cultures of Sertoli, Leydig, and germ cells for reverse-transcription and polymerase chain reaction (RT-PCR), the mRNA s of cathepsin B, C, D, H, L, and S were shown to be expressed by Sert oli and Leydig cells, whereas germ cells isolated from adult rats expr essed all of the above cathepsin mRNAs except cathepsin D. Throughout postnatal development and maturation, the testicular steady-state mRNA levels of cathepsin B, C, D, L, and S remain relatively unchanged wit h the exception of cathepsin H whose mRNA level increased during matur ation and peaked at 45-60 days of age. Using lonidamine, an anti-sperm atogenic drug which is known to induce premature release of germ cells without affecting Leydig cell function by disrupting the inter-Sertol i-germ cell junctions, we have examined the differential expression of these cathepsin mRNAs in the testis at the time of extensive tissue r estructuring. It was noted that the expression of cathepsin L and S in the testis increased significantly concomitant with the disappearance of elongate spermatids whereas the expression of cathepsin B, C, D, a nd H increased significantly when most of the round spermatids and spe rmatocytes were depleted. These results illustrate the intricate inter -relationship between these proteases in the testis during maturation and tissue restructuring.