Caracterización de la región promotora del gen bcl-X en rata

A. SOLER BISTUÉ, L. BARAÑAO Y A. PECCI

Villa Carlos Paz-Córdoba

Congreso; Reunión Anual de la Sociedad Argentina de Investigaciones Bioquímicas (SAIB); 2002

Sociedad Argentina de Investigaciones Bioquímicas (SAIB)

Differential splicing from bcl-X gene generates several isoforms with opposite on the apoptosis. Recently, we elucidated the complex structure of the mouse  bcl-X 5´-region. It contains five different promoters (P1 to P5) with tissue specific activity. In the rat, bcl-X would have a different pattern of expression . According to RT-PCR assays, P1 and P2 were active in mouse brain thymus and liver but not in those rat tissues. In this work we analysed the 5´-region from the rat gene . Comparison between the mouse gene to the Rat Genome Proyect  revealed more than 90% of homology (clon AC129342.2). P1, P2 and P3 are completely conserved suggesting that the different expression patterns would not be due to the promoter sequences. Further analisys showed that the homology diminishes abruptly upstream P3. In fact, we found two putative TATA-box promoters which differ from the mouse P4 and P5 in at least five nucleotides. Even thought these results are not conclusives they suggest how different could be the expression between phylogeneticaly close species. Moreover, while tracking P2 in rat genome, we obtained a PCR product with an inferior lenght to the expected . It´s sequentiation demonstrated the lack of an intronic region. Using computational ressourses we located an additional region in the rat genome with high homology to the codifying region of bcl-X but lacking introns (clon AC098008). These evidences suggest the existance of a retropseudogene of bcl-X in the genome of this rodent.