Expression and functional role of hepatocyte growth factor receptor (C-MET) during postnatal rat testis development

The met protooncogene encodes the hepatocyte growth factor receptor (HGFR, c-met). C-met, a tyrosine kinase receptor protein, is widely expressed in d ifferent cell types including the male reproductive tract. As we recently d emonstrated, both c-met messenger RNA and protein are expressed in prebuber al rat testis. The aim of this work was to detect the expression of c-met d uring postnatal testis development and to study its functional role. Our fi ndings show that in total rat testis e-met is expressed during postnatal li fe until the sexual maturation of the animals. To evaluate the receptor exp ression in the different cell types in the testis, homogeneous cell populat ions of Sertoli and peritubular myoid cells were isolated from the seminife rous tubules of 10- and 35-day-old animals. c-met gene is expressed in myoi d cells at the ages considered and its expression decreases with increasing age. By contrast, in Sertoli cells c-met expression is first detectable at 25 days of Life and its expression increases with the increasing age being well evident at 35 days of age. C-met protein was detected by immunocytoch emistry and its expression correlates with gene expression. The receptor is functionally active because HGF administration induces morphological chang es in myoid cells and in c-met-expressing Sertoli cells. As a consequence o f HGF addition, Sertoli cells cultured on reconstituted basement membrane r eorganize into cord-like structures that resemble testicular seminiferous c ords. The data here reported demonstrate for the first: time that in Sertol i cells c-met expression is developmentally regulated being present and fun ctionally active in postpuberal Sertoli cells. Given that c-met expression persists in myoid cells during postnatal testis development and that in Ser toli cells its expression correlates over time with germ cell differentiati on and lumen formation, we conclude that the c-met/HGF system is involved i n testis development and function.