Modifiers of polyglutamine disease pathogenesis

Lead Research Organisation: University of Cambridge
Department Name: Cambridge Institute for Medical Research

Abstract

Huntington?s disease (HD) is an incurable, disease affecting the brain. It results in abnormal movements, psychiatric disturbances (like depression) and memory problems. HD is a genetic disease and about half of the children of affected individuals are at-risk of developing the disease. A number of studies suggests that there are genetic factors distinct from the primary HD mutation that can modulate the severity of the disease or its age-at-onset. This proposal aims to characterise genetic pathways that reduce the severity of HD in animal models. These genes and pathways will be used to prioritise and eventually select druggable targets for further investigation, e.g. with the aim of developing possible therapies. We will identify such modifiers using mouse and fly models of HD and two complementary genetic approaches that allow us to screen for such modifier genes. The logistics and screening systems for these screens have been established in current MRC grants held by the applicants. We have accumulated a large amount of pilot data that show the likely success of this program. The research will be performed by Prof David Rubinsztein and Dr Cahir O?Kane (University of Cambridge) and Prof Steve Brown (MRC Mammalian Genetics Unit, Harwell).

Technical Summary

Huntington?s disease (HD) is an incurable, autosomal dominant neurodegenerative disease. It is caused by the abnormal expansion of a CAG trinucleotide repeat close to the N-terminal of the coding part of the gene encoding huntingtin. The CAG repeats encode an expanded polyglutamine (polyQ) repeat tract. About 70% of the variance in the age at onset of HD can be accounted for by CAG repeat number in the disease-causing allele. The residual variance in age at onset unaccounted for by the CAG repeat numbers is likely to be partly due to genetic factors. This proposal aims to characterise genetic pathways that suppress polyglutamine toxicity in vivo. These genes and pathways will be used to prioritise and eventually select druggable targets (e.g. G-protein coupled receptors, ion channels, enzymes and nuclear receptors) for further investigation. We will identify such modifiers using mouse ENU mutagenesis and genome-wide RNAi analysis in fly models integrated with cell biology studies of modifiers. The logistics and screening systems for the mouse ENU program and the RNAi fly screen have been established in current MRC grants held by the applicants. For the ENU program, we have been identifying dominant enhancer or suppressor mutations of the polyQ phenotype by mating hemizygous female transgenic mice expressing the first 171 residues of huntingtin with 82 repeats on a C3HxC57BL/6 background with BALB/c male mice that have been mutagenised with ENU. To date, the screen has been fruitful, yielding 18 phenodeviants - 11 enhancers and 7 suppressors. In the continuation of the program, we aim to identify the causal modifier mutations and continue with restricted further screening focussing on suppressors. For the fly screen, we have developed a moderate-throughput system using polyQ flies expressing the mutant transgene in the eyes. The polyQ fly eyes show loss of pigmentation and necrotic spots. These flies are crossed to RNAi-bearing flies, to give progeny that express both the mutant polyQ allele and the RNAi in the same cells. After optimising the system, we are now screening ~1000 RNAi lines per month. So far we have screened ~2000 crosses, with a suppressor hit rate of ~2.3% and enhancer hit rate of ~9%. For the new program, we aim to complete the genome?wide screen, focussing on supressors. We will select high priority hits from this screen that are conserved in humans, elucidate their functional roles and confirm that they act in the same way in mouse models.

Publications

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Anichtchik O (2008) Loss of PINK1 function affects development and results in neurodegeneration in zebrafish. in The Journal of neuroscience : the official journal of the Society for Neuroscience

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Corrochano S (2012) a-Synuclein levels modulate Huntington's disease in mice. in Human molecular genetics

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Diekmann H (2009) Decreased BDNF levels are a major contributor to the embryonic phenotype of huntingtin knockdown zebrafish. in The Journal of neuroscience : the official journal of the Society for Neuroscience

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Eriguchi M (2010) alpha Pix enhances mutant huntingtin aggregation. in Journal of the neurological sciences

 
Description Training Fellowship
Amount £193,442 (GBP)
Organisation Action Medical Research 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2007 
End 09/2010
 
Description Wellcome Trust/MRC Strategic Award for Neurodegeneration (CONSORTIUM on "Mechanisms of neurotoxicity of amyloid aggregates")
Amount £6,155,690 (GBP)
Funding ID 089703/Z/09/Z 
Organisation Wellcome Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 03/2010 
End 02/2015
 
Description Studies of antioxidants as modifiers of Huntington disease 
Organisation Medical Research Council (MRC)
Department MRC Mitochondrial Biology Unit
Country United Kingdom 
Sector Academic/University 
PI Contribution We have done the bulk of the experiments on Huntingtons models, but Dr Murphy has done work on the compounds themselves
Collaborator Contribution Intellectual input, novel compounds, testing compounds in normal mice
Impact PubMed ID: 19854266
Start Year 2006
 
Title Therapeutic strategy for Huntington's disease 
Description We found that Rilmenidine an antihypertenisve drug, can induce autophagy and thereby remove mutant huntingtin. This attenuates the severity and delays onset of disease in a mouse model of this disease 
Type Preventative Intervention - Nutrition and Chemoprevention
Current Stage Of Development Early clinical assessment
Year Development Stage Completed 2009
Development Status Under active development/distribution
Impact We are planning a safety trial soon in Huntington's idease patients. 
 
Description 15 international conferences in 2016 - speaker 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact conference presentations at internationa; meetings: Black Forest Winter Conference: "Autophagic Membrane Trafficking & Dynamics in Ageing and Disease" (Freiburg 2016), CHDI's 11th Annual Therapeutics Conference (Palm Springs 2016), International Congress of Human Genetics (Kyoto, 2016), Neuroscience School of Advanced Studies - Autophagy and neuroprotection (Cortona - lecture course 2016), International Society for Developmental Neuroscience (2016, Juan les Pins), European Neuroscience Institute 15th Anniversary Symposium (Gottingen 2016), Keystone Autophagy symposium (Whistler, 2016), Mitochondria: balancing health and disease (London 2016), Nobel conference - The Cell Cycle and Cell Death in Disease (Stockholm, 2016), Centre for Translational Cell Research opening sympiosium (Freiburg 2016), PhD graduate Symposium Cologne Graduate School of Aging Research (2016), Cold Spring Harbor meeting: Neurodegenerative Diseases: Biology & Therapeutics (Cold Spring Harbor 2016), Milner Therapeutics Institute Symposium (Cambridge 2016), 26th Annual Meeting of the Network for European CNS Transplantation & Restoration (NECTAR), Cambridge 2016)
Year(s) Of Engagement Activity 2016
 
Description Interview with press 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Participants in your research and patient groups
Results and Impact Interviews with journalists at different jounrals

Interest in the field; published articles
Year(s) Of Engagement Activity 2010
 
Description Talks at international conferences 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact India-EMBO Autophagy Symposium (Bubaneswar 2017), Autophagy as a Common Pathway in Diseases (NIH, Bethesda 2018), Gordon Conference -Autophagy in Stress, Development and Disease (Il Ciocco, 2018), Interact (Munich, 2018), Autophagy and Neuroprotection (Teaching course, Venice 2018), 83rd Harden Conference Autophagy - from Molecules to Disease (Warwick 2018), Gordon conference - Neurobiology of Brain Disorders (Castelldefels, Spain, 2018), Workshop on Autophagy in model organisms (Budapest, 2018), Autophagy in the healthy and diseased brain - Lake Como School of Advanced Studies (2018), 7th International Student Symposium conducted by the International Max Planck Research School in Chemical and Molecular Biology (Dortmund) (2018)
Year(s) Of Engagement Activity 2018
 
Description Talks at international conferences 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Keystone Symposium: Autophagy: From Model Systems to Therapeutic Opportunities (Santa Fe 2019), Autophagy, Inflammation & Metabolism Annual Meeting & Symposium (Albuquerque (2019), British Inflammation Research Association meeting on Autophagy (2019), FASEB - The Protein Aggregation Conference (Snowmass, 2019), Gordon Research Conference on Stress Proteins in Growth, Development and Disease (Barga, 2019), Imperial College Alzheimer's Research Network Symposium (London 2019), EMBO Autophagy Workshop 2019 (Crieff, Scotland), European Society of Neurochemistry 2019 (Milan), Basel Life - Aging and drug discovery and AI (Basel, 2019), Inaugural International Symposium of Cell Fate Determination (Shanghai 2019), 9th International Symposium on Autophagy (Taipei 2019), Alzheimer's Research UK East Network 2019 Annual Scientific meeting (Cambridge 2019), Roger de Spoelberch Prize 10 years Symposium (Geneva, 2019)
Year(s) Of Engagement Activity 2019
 
Description Talks for Medical Students societies 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Undergraduate students
Results and Impact St Johns College Medical Society Cambridge (2017)
Trinity College Medical Society (2019)
Year(s) Of Engagement Activity 2017,2019
 
Description Talks for lay audiences/patients 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Patients, carers and/or patient groups
Results and Impact Addenbrooke's Hospital Huntington's disease patients (2018); Addenbrooke's Hospital Parkinson's disease patients (2018)
Year(s) Of Engagement Activity 2018