Y. Saintigny et al., A novel role for the Bcl-2 protein family: specific suppression of the RAD51 recombination pathway, EMBO J, 20(10), 2001, pp. 2596-2607
The oncogenic role of Bcl-2 is generally attributed to its protective effec
t against apoptosis, Here, we show a novel role for Bcl-2: the specific inh
ibition of the conservative RAB51 recombination pathway. Bcl-2 or Bcl-X-L o
verexpression inhibits UV-C-, gamma -ray- or mutant p53-induced homologous
recombination (HR), Moreover, Bcl-2 recombination inhibition is independent
of the role of p53 in G(1) arrest. At an acute double-strand break in the
recombination substrate, Bcl-2 specifically inhibits RAD51-dependent gene c
onversion without affecting non-conservative recombination. Bcl-2 consisten
tly thwarts recombination stimulated by RAD51 overexpression and alters Rad
51 protein by post-translation modification, Moreover, a mutant (G145A)Bcl-
2, which is defective in pax interaction and in apoptosis repression, also
inhibits recombination, showing that the death and recombination repression
functions of Bcl-2 are separable. Inhibition of error-free repair pathways
by Bcl-2 results in elevated frequencies of mutagenesis, The Bcl-2 gene th
erefore combines two separable cancer-prone phenotypes: apoptosis repressio
n and a genetic instability/mutator phenotype, This dual phenotype could re
present a mammalian version of the bacterial SOS repair system.