Cs. Teng, GOSSYPOL-INDUCED APOPTOTIC DNA FRAGMENTATION CORRELATES WITH INHIBITED PROTEIN-KINASE-C ACTIVITY IN SPERMATOCYTES, Contraception, 52(6), 1995, pp. 389-395
After exposure of cultured rat spermatocytes to gossypol acetic acid f
or five hours, DNA fragmentation in a ladder pattern was found in the
medium and supernatants of cell lysates. The concentrations of gossypo
l used for the induction of apoptosis ranged from 100 mu M to 300 mu M
. Within this dose range, gossypol was also found to be effective at i
nhibiting protein kinase C (PKC) activity. This inhibitory effect was
demonstrated by measuring the PKC residing in cytosolic and particulat
e fractions. However, the gossypol-induced inhibition of PKC activity
was protected by phorbol 12,13-dibutyrate (PDBu), an activator of PRC.
Furthermore, the presence of PDBu prevented gossypol-induced DNA frag
mentation. These results suggest that spermatocyte apoptosis induced b
y gossypol is correlated with the reduction of PKC activity, and that
maintenance of PKC basal activity is essential for protecting the sper
matocyte from apoptosis.