RESUMO
The t(11;22) is the most common recurrent non-Robertsonian constitutional translocation in humans, having been reported in more than 160 unrelated families. Balanced carriers are at risk of having offspring with the derivative 22 syndrome owing to 3:1 meiotic non-disjunction event. Clinical features of the der(22) syndrome include mental retardation, craniofacial abnormalities and congenital heart defects. The breakpoints for the t(11;22) translocation have been mapped to specific Alu repeats on chromosomes 11 and 22, indicating that this event is due to an Alu-Alu recombination. Remarkably, in five samples derived from individuals with no apparent common ancestry the der(11) and der(22) breakpoints appear to be almost identical at the genomic sequence level. The small number of base differences between the samples indicates some variation in the position of the breakpoints, although this appears to be quite limited. Indeed, the der(11) breakpoints are all located within a region of just 32 bp and the der(22) breakpoints within 21 bp. If, as suggested by current data, the widespread occurrence of this translocation is due to multiple independent events, our results suggest that this particular Alu-Alu recombination is subject to an unprecedented degree of selection.
Assuntos
Elementos Alu/genética , Cromossomos Humanos Par 11 , Cromossomos Humanos Par 22 , Recombinação Genética , Translocação Genética , Adulto , Sequência de Bases , Southern Blotting , Linhagem Celular , Humanos , Hibridização in Situ Fluorescente , Lactente , Recém-Nascido , Dados de Sequência Molecular , Placenta/metabolismo , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Homologia de Sequência do Ácido NucleicoRESUMO
We designed experiments to study the effects on P210BCR/ABL expression of introducing antisense oligonucleotides into K562 cells. We used two antisense oligonucleotides: one (AS1) is complementary to the first coding codon of the BCR/ABL mRNA and the two 5' and three 3' codons, and the other (AS2) to BCR coding codons 5 to 11 inclusive. To facilitate entry of the oligonucleotides the K562 cells were subjected to electroporation on three occasions at 24 hr intervals (0, 24 and 48 hr). P210BCR/ABL expression was assayed by in vivo phosphorylation followed by immune precipitation with a BCR antibody. Introduction of AS1 inhibited P210BCR/ABL expression at 72 and 96 hrs, whereas AS2 and the control oligonucleotide had no effect. AS1 also killed K562 cells. We conclude that selected antisense oligonucleotides can modify leukaemia-specific protein expression in K562 cells. This approach could prove valuable for purging CML bone marrow cells in vitro.
