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Epigenetic analysis of promiscuous gene expression in central tolerance

Heath, Jennifer Noelle (2010)
Ph.D. thesis, University of Birmingham.

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Abstract

The autoimmune regulator (AIRE), a key player in negative selection of developing thymocytes, acts as a transcriptional regulator, inducing the expression of tissue restricted antigens (TRA) within medullary thymic epithelial cells in a process known as promiscuous gene expression (PGE). Here we demonstrate how AIRE influences PGE through a direct impact on post-translational modifications of core histones which are associated with the regulation of transcription. Through native chromatin immunoprecipitation on thymic epithelial cells transfected with AIRE, we show how in vitro, TRA are enriched in active acetylation and methylation of core histones, yet retain silencing modifications. Furthermore, across a cluster of AIRE-regulated genes, histone modifications were deposited across the entire domain, dependent upon the expression profile of each gene, suggesting a role for domain-wide epigenetic regulation by AIRE. Extension of these studies in vivo, utilising the recently developed carrier ChIP technique, allowed examination of the epigenetic status of TRA throughout the thymic developmental pathway. We report how poised TRA are marked with combinations of active and silent modifications early in thymic development and that the chromatin signatures re-organise as the cells differentiate. The epigenetic patterning differs on a gene by-gene basis, however their significance is implied upon disruption to normal development as the predictive pattern of modifications is lost.

Type of Work:Ph.D. thesis.
Supervisor(s):O'Neill, Laura and Anderson, Graham
School/Faculty:Colleges (2008 onwards) > College of Medical & Dental Sciences
Department:School of immunity and infection
Subjects:RC Internal medicine
Institution:University of Birmingham
ID Code:613
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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