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|Type:||Artigo de periódico|
|Title:||Influence of the polymorphisms of the alpha-major regulatory element HS-40 on in vitro gene expression|
|Abstract:||The alpha-MRE is the major regulatory element responsible for the expression of human alpha-like globin genes. It is genetically polymorphic, and six different haplotypes, named A to F, have been identified in some population groups from Europe, Africa and Asia and in native Indians from two Brazilian Indian tribes. Most of the mutations that constitute the alpha-MRE haplotypes are located in flanking sequences of binding sites for nuclear factors. To our knowledge, there are no experimental studies evaluating whether such variability may influence the alpha-MRE enhancer activity. We analyzed and compared the expression of luciferase of nine constructs containing different alpha-MRE elements as enhancers. Genomic DNA samples from controls with A (wild-type alpha-MRE) and B haplotypes were used to generate C-F haplotypes by site-directed mutagenesis. In addition, three other elements containing only the G. A polymorphism at positions + 130, + 199, and + 209, separately, were also tested. The different alpha-MRE elements were amplified and cloned into a plasmid containing the luciferase reporter gene and the SV40 promoter and used to transiently transfect K562 cells. A noticeable reduction in luciferase expression was observed with all constructs compared with the A haplotype. The greatest reductions occurred with the F haplotype (+ 96, C. A) and the isolated polymorphism + 209, both located near the SP1 protein-binding sites believed not to be active in vivo. These are the first analyses of alpha-MRE polymorphisms on gene expression and demonstrate that these single nucleotide polymorphisms, although outside the binding sites for nuclear factors, are able to influence in vitro gene expression.|
|Subject:||Alpha-major regulatory element|
|Editor:||Assoc Bras Divulg Cientifica|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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