INCREASED RATIO OF BCL-2 BAX EXPRESSION IS ASSOCIATED WITH BOVINE LEUKEMIA VIRUS-INDUCED LEUKEMOGENESIS IN CATTLE/

To further investigate the molecular basis underlying the dysregulatio n of B cell homeostasis associated with bovine leukemia virus disease progression in cattle, bovine bar was cDNA cloned and sequenced. The p redicted amino acid sequence of bovine Bar revealed a 192-amino-acid p rotein having extensive identity with the human (97%), murine (93%), a nd rat (94%) homologues. Because the ratio of Bcl-2 to Bar is believed to predetermine the susceptibility to a given apoptotic stimulus, the relative expression of the genes encoding these oncoproteins was eval uated in cattle naturally infected with BLV. In BLV-infected cattle an increase in the ratios of bcl-2/bax mRNA and protein expression corre lated with advancing stages of disease. These findings suggest that in addition to the maintenance of BLV-associated hematopoietic malignanc ies, the reciprocal expression of Bcl-2/Bax may modulate the induction of B cell expansion typical of BLV disease progression. (C) 1998 Acad emic Press.