Cs. Teng et X. Vilagrasa, BIPHASIC C-MYC PROTEIN EXPRESSION DURING GOSSYPOL-INDUCED APOPTOSIS IN RAT SPERMATOCYTES, Contraception, 57(2), 1998, pp. 117-123
The presence of protooncogene products such as c-Myc proteins in rat s
permatocytes has been quantitatively detected by Western immunoblot an
d a computer-controlled Spot-denso-program with an IS-1000 digital ima
ging system. Cellular levels of c-Myc proteins in response to gossypol
were measured in spermatocytes during the process of gossypol-induced
apoptosis. Within 0.5 to 2 h of the addition of gossypol, levels of c
-Myc proteins fall dramatically and remain at a low level for the next
several hours. The reduction in c-Myc proteins occurs 4.5-6 h before
the apoptosis of spermatocytes in the presence of gossypol. Between 3
and 5 h after exposure to gossypol, the c-Myc protein content returns
to preexposure (or higher) levels. In addition, the increase in c-Myc
proteins occurs 1.5-4 h before the apoptotic death of spermatocytes. A
n identical pattern of c-Myc protein response to gossypol was also fou
nd in total testicular tissue in vitro. These results suggest that spe
rmatocyte apoptosis induced by gossypol is correlated with biphasic c-
Myc protein expression. This article presents some hypothetical models
with which to explain c-Myc protein-mediated apoptosis. (C) 1998 Else
vier Science Inc. All rights reserved.