Award Title: (Epi)genome editing to combat expanded CAG/CTG repeat disorders
Funder: Medical Research Council

Abstract: The UK Dementia Research Institute (UK DRI) is an initiative funded by the Medical Research Council, Alzheimer's Society and Alzheimer's Research UK.  Funding details for UK DRI programmes will be added in 2019. Expanded CAG/CTG repeats cause over 13 neurological and neuromuscular disorders, including Huntington disease, myotonic dystrophy, and several spinocerebellar ataxias. They affect 1 in 2000 people worldwide. The diseases are debilitating, often leading to dementia. There is currently no available cure. We aim to develop novel therapeutic avenues and to harness new technologies to detect (i.e., diagnose) and manipulate them. To achieve this, we use a variety of tools, including cutting edge molecular biology and genome engineering techniques, next-generation sequencing, as well as in vitro and in vivo pre-clinical disease models.   We focus on: 1) Gene editing and the mechanism of expanded CAG/CTG repeat instability Expanded CAG/CTG repeats are highly unstable somatically, leading to mutation frequencies of 100% in some tissues. The size of the repeat tract determines in large part the severity of the disease. Understanding this mechanism is essential to designing and optimising treatments aimed at contracting the repeat tract. We have recently developed a gene editing-based approach to contract the expanded repeat tract using the CRISPR-Cas9 system. We are currently determining whether this technology can slow, prevent, or reverse the disease phenotypes.  Representative reference: Cinesi et al (2016) Contracting CAG/CTG repeats using the CRISPR-Cas9 nickase. Nat Commun, 7, 13272. 2) The role of chromatin structure in the expression of expanded CAG/CTG repeats Expanded CAG/CTG repeats accumulate chromatin marks reminiscent of heterochromatin and are downregulated (but not completely silenced) compared to normal size repeats. In addition, there is genetic and biochemical evidence that expanded repeats require extra factors for efficient expression. Identifying these factors and identifying their mode of action may lead to the development of epigenome editing approaches to combat expanded CAG/CTG repeat disorders. Representative reference: Yang et al (2018) Uncovering the interplay between epigenome editing efficiency and sequence context using a novel inducible targeting system. BioRxiv.   3) Development of tools to manipulate and detect expanded CAG/CTG repeats  Determining repeat size for diagnostic purposes and for routine molecular biology applications is laborious. This is because of the repetitive nature and the inherent heterogeneity of the repeat size from cell to cell (i.e., repeat instability). Thus, there is a great need to improve on the current technologies. In addition, such system will help us determine whether any therapies involving contracting the repeat tracts are effective.  Representative reference: Malbec et al (2019) µLAS: Sizing of expanded trinucleotide repeats with femtomolar sensitivity in less than 5 minutes. Scientific Reports 9, (1):23.


Research Activity Codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING;2.1 BIOLOGICAL AND ENDOGENOUS FACTORS;4.5 RESOURCES AND INFRASTRUCTURE (DETECTION);5.2 CELLULAR AND GENE THERAPIES
Health Categories: NEUROLOGICAL