| Ամփոփում: | <p>The overall aim of the laboratory is to understand how the human α globin genes are expressed in a tissue-specific and developmental-stage specific manner from their natural chromosomal environment. This gene cluster has been studied in great detail from this point of view, and it now represents an important general model to address how eukaryotic genes are regulated. Ultimately, this information may be important for the further development of strategies for effective gene transfer, particularly for patients who suffer from inherited anaemias which result from abnormal globin gene expression (thalassemias).</p> <p>The human α globin gene cluster is located close to the telomere, in the terminal band of the short arm of chromosome 16 (16p13.3). Many aspects of α gene regulation have been studied in detail, including the identification of the structural genes, their proximal regulatory elements (promoters) and distal regulatory element (HS-40). Erythroidspecific <em>trans</em>-acting factors which bind these elements <em>in vitro</em> and <em>in vivo</em> have been identified. In an attempt to define the regulatory domain containing the α genes, the surrounding chromosomal environment (~400kb) has also been extensively studied. The region is fully sequenced, and the chromatin structure, methylation patterns and scaffold attachment sites have been established. Over 100 natural mutants that perturb α globin expression have been characterised and numerous fragments from this region have been analysed in transgenic mice.</p> <p>One potentially important aspect of α globin gene expression that has not been previously examined is DNA replication. Study of replication throughout this particular region provides an excellent opportunity to integrate this information with what is already known about the regulation of the α cluster. Initially, studies were undertaken to analyse the pattern and timing of DNA replication of the human α globin gene cluster and the surrounding chromosomal region in erythroid and non-erythroid cell-types. Replication timing of this region has also been compared in the individual paternal and maternal alleles of chromosome 16. Once the <em>in vivo</em> pattern of replication was established, the role of chromosomal position upon replication timing was assessed by analysing various constructs of the a cluster in transgenic mice. The role of the distal regulatory element HS-40 in influencing the pattern and timing of replication of the extended region has been examined. Naturally-occurring deletions within this region have facilitated the study of the importance of the telomere and subtelomeric region in determining the replication characteristics of this region. Replication has also been studied in another natural mutant, which contains a deletion which may perturb α gene expression by a novel mechanism.</p>
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