CD147 regulates apoptosis in mouse spermatocytes but not spermatogonia.

BACKGROUND: Spermatogenesis is maintained by a dynamic balance between germ cell proliferation and apoptosis. Previous study has demonstrated that CD147 knockout mice are infertile with arrested germ cells. However, the question of whether and how CD147 may be involved in the apoptotic process during spermatogenesis remains elusive. The aim of this study was to evaluate the role of CD147 in the regulation of germ cell apoptosis in mice. METHODS: CD147 function was blocked by anti-CD147 antibody in GC-1 (immortalized spermatogonia) and GC-2 (immortalized spermatocytes) cell lines and in testicular germ cells in vivo. Testes size and weight were examined after injection of anti-CD147 antibody into the seminiferous tubules of severe combined immunodeficiency mice. Germ cell apoptosis was determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and levels of p53 and two effectors, caspase 3 and poly ADP-ribose polymerase (PARP), using western blots. RESULTS: The size and weight of the CD147-immunodepleted testes were decreased compared with that in control testes (P < 0.001). The TUNEL assay showed an increase in the number of apoptotic spermatocytes (P < 0.001 versus control) but not spermatogonia in Stages XI-XII of CD147-immunodepleted testes. In addition, in vitro experiments demonstrated that CD147 immunodepletion induced an increase in apoptosis in GC-2 cells (P < 0.001 versus control) but had no effect on GC-1 cells. Moreover, deprivation of CD147 induced apoptosis in spermatocytes through a p53-independent mechanism, which led to caspase 3 and PARP activation. CONCLUSIONS: We have demonstrated that immunodepletion of CD147 induces p53-independent apoptosis in mouse spermatocytes but not spermatogonia.