A BCL-2-RELATED GENE IS ACTIVATED IN AVIAN CELLS TRANSFORMED BY THE ROUS-SARCOMA VIRUS

The oncoprotein p60(v-src) encoded by the Rous sarcoma virus (RSV) genome is the prototype of non-receptor tyrosine kinases. More than 50 targets of p60(v-src) have been described to date. However, the precise mechanisms of RSV transformation remain to be elucidated. Here, we present the study of a new v-src-activated gene, NR-13, which encodes a protein identified as a new member of the Bcl-2 family. This protein is localized in the membrane with a pattern already observed with Bcl-2. In quail embryos, this gene is mainly expressed in neural and muscular tissues. Its expression is dramatically down-regulated after embryonic day 7 (E7) in the optic tectum. To evaluate a possible role for NR-13 in the control of apoptotic processes in this particular brain area, in situ hybridization and DNA ladder fractionation studies were performed to correlate NR-13 expression with typical situations of apoptosis during brain development. Our results support the idea that RSV could activate anti-apoptotic functions of the host cell resulting in an increase of their lifespan, which could be particularly relevant to tumour formation.