Hepatocyte growth factor and c-MET are expressed in rat prepuberal testis

The hepatocyte growth factor (HGF) receptor (c-MET) is present in different mammalian tissues and transduces multiple biological effects. The HGF is k nown to regulate many fundamental cellular functions, such as cell growth, movement and differentiation, and is involved in embryonal morphogenesis. W e have studied HGF and c-MET expression in prepuberal rat testis. c-MET gen e expression was found in total testis and in homogeneous cell populations, as demonstrated by Northern blotting. In the seminiferous tubules, c-MET g ene was only expressed in the myoid cells. In these cells, c-MET was detect able and constantly expressed for at least six days of culture. The interst itial tissue was also c-MET positive. The protein encoded by the MET proto- oncogene was detected in myoid cells, and HGF administration to these cells induced morphological changes in the cells. HGF expression was not detecte d by Northern blotting using RNA extracted from total testis. By contrast, when homogenous cell populations were used, HGF expression was detectable a nd exclusively localized in myoid cells. Myoid cell-conditioned medium was able to induce scattering of canine kidney epithelial (MDCK) cells, and the scatter effect of a S-days conditioned medium was evident even after 7-fol d dilution of the medium. Our findings demonstrate that HGF and its recepto r are present in rat prepuberal testis. The coexpression of factor and rece ptor in the myoid cells suggests a new role for HGF as autocrine regulator of myoid cell function and, possibly, as regulator of mammalian testicular function.