Tyro 3 Family Receptors And Spermatogenesis

Tyro 3 family receptors contain 3 members, Axl, Tyro 3 and Mer, which were essential regulators of mammalian spermatogenesis. However, the exact expression patterns of the three members in testis and the mechanisms in regulating spermatogenesis remain unknown. In this study, we first examined expression dynamics and localizations of Axl, Tyro 3, Mer and their ligand Gas6 in mouse testes during postnatal development. All three members and their ligand were continuously expressed in different testicular cells. Tyro 3 was exclusively expressed in Sertoli cells with a varied distribution during testis development. At days 3 to 7 postnatal, Tyro 3 was distributed in overall cytoplasmic membrane and cytoplasm of Sertoli cells. From days 14 to 35, Tyro 3 appeared on Sertoli cell processes toward adluminal compartment of seminiferous tubules. A stage-dependent Tyro 3 immunoexpression in Sertoli cells was shown by adulthood testis at day 56 postnatal with higher expression at stages â…  -â…§ and lower level at stages â…¨-â…« Axl showed a similar expression pattern to Tyro 3, except for some immunopositive Leydig cells detected in mature testis. By contraries, immunostaining of Mer was detected mainly in primitive spermatogonia and Leydig cells, while a relative weak signal was found in Sertoli cells. Gas6 was strongly expressed in Leydig cells, and weakly in primitive spermatogonia and Sertoli cells. The results from RT-PCR showed that the mRNA levels of Axl and Tyro 3 were evidently increased in the postnatal developmenting Sertoli cells. The Mer mRNA was weakly expressed in the Sertoli cells and did not show obvious changes during development. These expression patterns of Tyro 3 family receptors and ligand in testis provide the basis for further study their functions and mechanisms in regulating mammalian spermatogenesis.Next, we used Tyro 3 family receptors mutant mice to study the roles of Tyro 3 family receptors in regulating spermatogenesis. The results showed that Axl, Tyro 3, and Mer additively maintain spermatogenesis. Young adult (5-8 weeks old) triple null (ATM) male mice produced complete spermatozoa, but showing oligo-astheno-teratozoospermia. The...