Understanding the pathogenesis of myotonic dystrophy type 1

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

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 > School of Molecular Biosciences > Molecular Biosciences
• 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: https://theses.gla.ac.uk/id/eprint/478