A Study of the Transcriptional Regulation of the Defensin Genes

Genetics

Phillips, Andrew Christopher

University:University of Glasgow

关键词: Genetics;   

Others  :  http://theses.gla.ac.uk/75523/1/13832492.pdf

来源: University of Glasgow

【 摘 要 】

A study of the transcriptional regulation of the defensin genes The defensin genes are expressed almost exclusively within a narrow window of myeloid differentiation, namely at the myelocyte stage of granulopoiesis. These genes encode peptides which are involved in the granulocytes response to infection and inflammation, being capable of destroying a wide range of organisms. The limited expression pattern of these genes suggests they would provide a good model to study mechanisms of both myeloid and differentiation-stage-specific gene expression. By studying the regulation of these genes, it may be possible to identify transcription factors which control both lineage-specific gene expression and differentiation in the myeloid compartment. This information may provide an insight into the process of maturation arrest and leukaemogenesis. Initial work was undertaken to identify a system in which to study the regulation of these genes. However, despite previous reports, no expression could be detected or induced in any myeloid cell line tested. DNAse 1 hypersensitivity analysis was carried out on a range of primary samples and both myeloid and non-myeloid cell lines. This analysis identified a number of DNAse 1 hypersensitive sites in the chromatin. One of these sites spanned the promoter and this was analysed in some detail. Both in vitro binding studies and transfection of reporter constructs were used to investigate if this promoter could mediate myeloid and/or differentiation-stage- specific activity. A number of DNA binding activities were identified which were markedly regulated during myeloid differentiation. This, in conjunction with the transfection data, allows models to be produced to explain both the myeloid and differentiation-stage-specific activity of these genes. Evidence is provided implicating the defensin genes as targets for regulation by the transcription factor c-Myb. This factor acts through a composite element within the defensin promoter which also binds a C/EBP-like factor. In addition, Ets-like transcription factors are implicated in mediating the myeloid specificity of these genes.