Huntington's disease (HD) is a devastating and fatal neurodegenerative disorder caused by the expansion of a polymorphic CAG repeat in the HTT gene that triggers cell death with a specificity towards neurons in the striatum and cortex. Although the underlying genetic mutation was discovered over 20 years ago, there is still no cure or effective treatment despite extensive efforts. The HTT CAG repeat mutation is highly unstable both in transmissions to subsequent generations and somatically. Notably the repeat undergoes dramatic tissue-specific somatic expansion, particularly in the brain regions affected in the disorder, strongly suggesting that somatic HTT CAG length increases in target tissues contribute to HD pathogenesis. We have shown in accurate genetic HD knock-in mouse models that genes in the mismatch repair (MMR) pathway (Msh2, Msh3, Mlh1, Mlh3) are critical for CAG expansion and enhance the pathogenic process. The relevance of these findings to HD patients is indicated by a recent genome-wide association study in which MLH1 SNPs were associated with motor onset, and more generally, in which DNA repair pathways were highlighted as a source of disease modification. In this study we will: 1) perform genetic experiments in HD knock-in mice that will provide insight into mechanism(s) of MMR-dependent instability and pathogenesis; 2) test the impact of MLH1 SNPs in HD patients on gene expression, cellular phenotypes and on somatic and intergenerational repeat instability; 3) Use gene knockdown and gene editing approaches to test the impact of additional DNA repair genes, implicated as disease modifiers in patients, as modifiers of instability and striatal pathogenesis in HD knock-in mice. Together, these experiments will provide critical insight into pathways and mechanisms by which MMR/DNA repair genes modify pathogenesis, which will directly impact on the development of therapeutics that promise to target mechanism(s) that occur very early in the disease process.

Public Health Relevance

Huntington's disease is a devastating and fatal neurodegenerative disorder for which there is no cure or effective treatment. The combination of emotional, cognitive and motor symptoms, leading to long-term care needs results in an extremely high healthcare cost, estimated at 25 billion dollars a year. This study is aimed at identifying early modifiers of disease with the potential of discovering novel targets for early therapeutic intervention

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS049206-12
Application #
9145790
Study Section
Genetics of Health and Disease Study Section (GHD)
Program Officer
Miller, Daniel L
Project Start
2004-07-01
Project End
2020-06-30
Budget Start
2016-07-01
Budget End
2017-06-30
Support Year
12
Fiscal Year
2016
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
073130411
City
Boston
State
MA
Country
United States
Zip Code
Bragg, Robert M; Coffey, Sydney R; Weston, Rory M et al. (2017) Motivational, proteostatic and transcriptional deficits precede synapse loss, gliosis and neurodegeneration in the B6.HttQ111/+ model of Huntington's disease. Sci Rep 7:41570
Neto, João Luís; Lee, Jong-Min; Afridi, Ali et al. (2017) Genetic Contributors to Intergenerational CAG Repeat Instability in Huntington's Disease Knock-In Mice. Genetics 205:503-516
Ament, Seth A; Pearl, Jocelynn R; Grindeland, Andrea et al. (2017) High resolution time-course mapping of early transcriptomic, molecular and cellular phenotypes in Huntington's disease CAG knock-in mice across multiple genetic backgrounds. Hum Mol Genet 26:913-922
Galkina, Ekaterina I; Shin, Aram; Coser, Kathryn R et al. (2014) HD CAGnome: a search tool for huntingtin CAG repeat length-correlated genes. PLoS One 9:e95556
Pinto, Ricardo Mouro; Dragileva, Ella; Kirby, Andrew et al. (2013) Mismatch repair genes Mlh1 and Mlh3 modify CAG instability in Huntington's disease mice: genome-wide and candidate approaches. PLoS Genet 9:e1003930
Hölter, Sabine M; Stromberg, Mary; Kovalenko, Marina et al. (2013) A broad phenotypic screen identifies novel phenotypes driven by a single mutant allele in Huntington's disease CAG knock-in mice. PLoS One 8:e80923
Lee, Jong-Min; Galkina, Ekaterina I; Levantovsky, Rachel M et al. (2013) Dominant effects of the Huntington's disease HTT CAG repeat length are captured in gene-expression data sets by a continuous analysis mathematical modeling strategy. Hum Mol Genet 22:3227-38
Staropoli, John F; Haliw, Larissa; Biswas, Sunita et al. (2012) Large-scale phenotyping of an accurate genetic mouse model of JNCL identifies novel early pathology outside the central nervous system. PLoS One 7:e38310
Mochel, Fanny; Durant, Brandon; Meng, Xingli et al. (2012) Early alterations of brain cellular energy homeostasis in Huntington disease models. J Biol Chem 287:1361-70
Kovalenko, Marina; Dragileva, Ella; St Claire, Jason et al. (2012) Msh2 acts in medium-spiny striatal neurons as an enhancer of CAG instability and mutant huntingtin phenotypes in Huntington's disease knock-in mice. PLoS One 7:e44273

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