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Understanding the pathogenesis of myotonic dystrophy type 1

Haworth, Christine (2008) Understanding the pathogenesis of myotonic dystrophy type 1. PhD thesis, University of Glasgow.

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Abstract

To identify the full range of targets and the pathogenic consequences, we sought to mimic the pathogenesis of myotonic dystrophy type 1 with temporal and spatial control: temporal to reproduce the developmental pathogenesis of the congenital form, and spatial to isolate tissue specific pathology. To do this, we attempted to use the Cre-lox system for the conditional expression of an EGFP reporter-linked expanded CUG repeat RNA in the mouse. Expression of the transgene was controlled by Cre excision of a transcriptional stop, placed upstream of the EGFP-expanded repeat open reading frame. The transgenes were constructed and tested successfully, and a normal length repeat transgenic line was established. Unfortunately generation of the expanded repeat line was not successful. The constructs were used to generate cell-culture models of DM1, in both human and murine cells, which mimicked the nuclear foci formation and MBNL1 co-localisation seen in patient cells. Expression of exogenous MBNL1/GFP fusion protein in this model resulted in an increase in the size of foci, indicating that MBNL1 protein is limiting within the cell, and may possibly play a protective role. The murine DM1 cell-culture model was used to investigate the effects of expanded CUG repeat expression on splicing within the transcriptome. The differential effect between 5 and 250 repeat RNA expression using Affymetrix whole transcript and exon arrays was compared. Using whole genome arrays, 6 genes were down-regulated and 128 upregulated. With exon arrays, 58 genes showed alternative exon usage. Six genes were selected for further bioinformatics analysis: MtmR4, which has possible neuromuscular involvement; Kcnk4, Narg1, Ttyh1 and Bptf, potentially related to brain development; and Cacna1c, a promising candidate for heart conductance defects and sudden death.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Subjects: Q Science > QH Natural history > QH426 Genetics
Colleges/Schools: College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology > Molecular Cell and Systems Biology
Supervisor's Name: Monckton, Professor D. G.
Date of Award: 2008
Depositing User: Mrs Marie Cairney
Unique ID: glathesis:2008-478
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 12 Dec 2011
Last Modified: 10 Dec 2012 13:18
URI: http://theses.gla.ac.uk/id/eprint/478

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