MOLECULAR-CLONING OF THE RAT TPX-1 RESPONSIBLE FOR THE INTERACTION BETWEEN SPERMATOGENIC AND SERTOLI CELLS

We previously showed in a primary culture of rat testicular cells that spermatogenic cells specifically bind to somatic Sertoli cells and th at this interaction is needed for spermatogenic cells to differentiate in vitro. Adopting an expression cloning procedure, we here isolated a cDNA coding for a spermatogenic cell protein whose expression gave a cultured cell line the ability to bind to Sertoli cells. The protein, 243 amino acids with a putative N-terminal signal peptide and a C-ter minal Cys-rich region, turned out to be the rat homologue of a testicu lar protein called Tpx-1 whose function had yet to be determined. A po lyclonal antibody raised against bacterially expressed Tpx-1 significa ntly inhibited the binding of spermatogenic cells to Sertoli cells. Th e above results indicated that Tpx-1 is a testicular cell adhesion mol ecule responsible for the specific interaction between spermatogenic a nd Sertoli cells. (C) 1998 Academic Press.