Mesenchymal entactin-1 (nidogen-1) is required for adhesion of peritubularcells of the rat testis in vitro

Epithelial-like Sertoli cells isolated from immature rat testis aggregate t o form tubule-like structures when cultured on a monolayer of mesenchyme-de rived peritubular cells. At the end of this morphogenetic process both cell types are separated by a basement membrane. In this study the gene express ion of monocultures and direct cocultures of peritubular cells and Sertoli cells was examined using DD-RT-PCR. One of the isolated cDNA clones showed high homology to the cDNA encoding the basement membrane component entactin -1 (nidogen-1), Even though the entactin-1 (nidogen-1) gene is transcribed in peritubular cells, Sertoli tells, and in direct cocultures, the mRNA is translated only by the peritubular cells. No entactin-1 (nidogen-1) was det ected in the Sertoli cells by Western blotting, Moreover, peritubular cell monocultures and cocultures showed the presence of one single band at 152 k Da in the supernatant, whereas in cell lysates two bands were detectable at 152 kDa and 150 kDa, Perturbation experiments using monoclonal antibodies directed against entactin-1 (nidogen-1) were performed with peritubular cel ls and Sertoli cells, respectively, and demonstrated loss of cell adhesion of the peritubular cells, while the Sertoli cells remained adherent. From t hese data we conclude that entactin-1 is exclusively produced and secreted by mesenchymal peritubular cells, and affects adhesion of peritubular cells in an autocrine manner.