N-CADHERIN MEDIATES SERTOLI CELL-SPERMATOGENIC CELL-ADHESION

The complex topological association of Sertoli cells and spermatogenic cells in the testis suggests the existence of cell surface adhesion m olecules that regulate cellular interactions within the seminiferous e pithelium. The recent report of N-cadherin mRNA expression in the mous e testis implies the involvement of this known adhesion molecule in te sticular cell binding. Accordingly, here we report that (1) N-cadherin is found on the surface membranes of rat spermatogenic cells and on S ertoli cells, and (2) that N-cadherin is a partial mediator of Sertoli cell-germ cell adhesion as tested in an in vitro cell-cell binding as say. Antiserum directed against the N-cadherin cell adhesion recogniti on sequence was used for Western blot analysis of purified plasma memb ranes from Sertoli cells and from spermatogenic cells. Both membrane p reparations exhibited reactivity at an appropriate M(r) of about 130 k Da. In addition, immunofluorescence assays demonstrated that both germ cells and Sertoli cells were labeled by anti-N-cadherin. Finally, the antiserum was included in a cytometer-assisted cell-cell binding test to determine its inhibitory ability. The antiserum consistently reduc ed specific testicular cell-cell adhesion by 30%-50%. This is the firs t demonstration that antibodies directed against the cadherin cell adh esion recognition sequence are capable of inhibiting cell-cell interac tions. Pre-incubation of either rat Sertoli cells or spermatogenic cel ls alone was sufficient to achieve statistically significant inhibitio n of intercellular adhesion. We conclude, therefore, that N-cadherin i s expressed by both Sertoli cells and spermatogenic cells and that N-c adherin is one of a number of regulatory molecules mediating local cel lular associations in the mammalian seminiferous tubule. (C) 1993 Wile y-Liss, Inc.