Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are neurodegenerative diseases with clinical, pathological and genetic overlap. The expansion of a hexanucleotide repeat in a non-coding region of C9ORF72 is the major genetic cause of FTD and ALS. Elucidating how these expanded repeats cause """"""""c9FTD/ALS"""""""" has since become an important goal of the field. Our recent study identifying a new pathological hallmark of c9FTD/ALS - the accumulation of neuronal inclusions composed of peptides produced by repeat associated non-ATG (RAN) translation of sense and antisense transcripts of the expanded repeat - implicates RAN translation as a mechanism of disease. This unconventional mode of translation was first described for expanded CAG?CTG repeats and accounts for the accumulation of polyA or polyQ proteins in spinocerebellar ataxia type 8 and myotonic dystrophy type 1, respectively. Based on our findings that RAN translation of expanded repeats similarly occurs in c9FTD/ALS, we believe that peptides thusly produced play a role in disease pathogenesis. This project aims to investigate this pressing question, as well as several others. Specifically, we will evaluate whether: 1) the various peptides produced via RAN translation show a differential pattern of expression in c9FTD/ALS;2) there is differential toxicity among RAN translated peptides or among soluble and insoluble species;3) toxicity is enhanced by loss of C9ORF72 function;and 4) expression of RAN translated peptides influences disease phenotype or depend upon repeat length. To investigate these questions we will utilize novel antibodies, develop new cell culture and animal models, and examine fibroblasts and tissues from c9FTD/ALS patients. In addition to being subject to RAN translation, accumulating sense (GGGGCC)exp and antisense (CCCCGG)exp RNA transcripts may result in the sequestration of RNA-binding proteins in c9FTD/ALS. Nuclear RNA foci of expanded RNA transcripts accumulate in frontal cortex, spinal cord and cerebellum of C9ORF72 repeat expansion carriers. The sequestration and inactivation of RNA- binding proteins by RNA foci is observed in several repeat expansion diseases and is thought to account for some features of disease. The identification of RNA-binding proteins sequestered by transcripts of expanded repeats in C9ORF72, and determining whether the function of these proteins are altered in c9FTD/ALS, will increase our understanding of this potential mechanism of disease. Overall, the goals of Project 2 are to test the hypothesis that transcripts of expanded repeats contribute to c9FTD/ALS pathogenesis via two mechanisms: by RAN translation and by the mis-regulation of RNA-binding proteins.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Program Projects (P01)
Project #
1P01NS084974-01A1
Application #
8754967
Study Section
National Institute of Neurological Disorders and Stroke Initial Review Group (NSD)
Project Start
Project End
Budget Start
2014-09-30
Budget End
2015-06-30
Support Year
1
Fiscal Year
2014
Total Cost
$64,555
Indirect Cost
$23,306
Name
Mayo Clinic Jacksonville
Department
Type
DUNS #
153223151
City
Jacksonville
State
FL
Country
United States
Zip Code
32224
Nicolas, Aude (see original citation for additional authors) (2018) Genome-wide Analyses Identify KIF5A as a Novel ALS Gene. Neuron 97:1268-1283.e6
Nicholson, Alexandra M; Zhou, Xiaolai; Perkerson, Ralph B et al. (2018) Loss of Tmem106b is unable to ameliorate frontotemporal dementia-like phenotypes in an AAV mouse model of C9ORF72-repeat induced toxicity. Acta Neuropathol Commun 6:42
Kang, Silvia S; Ebbert, Mark T W; Baker, Kelsey E et al. (2018) Microglial translational profiling reveals a convergent APOE pathway from aging, amyloid, and tau. J Exp Med 215:2235-2245
Gendron, Tania F; Petrucelli, Leonard (2018) Disease Mechanisms of C9ORF72 Repeat Expansions. Cold Spring Harb Perspect Med 8:
Ebbert, Mark T W; Farrugia, Stefan L; Sens, Jonathon P et al. (2018) Long-read sequencing across the C9orf72 'GGGGCC' repeat expansion: implications for clinical use and genetic discovery efforts in human disease. Mol Neurodegener 13:46
Wang, Zi-Fu; Ursu, Andrei; Childs-Disney, Jessica L et al. (2018) The Hairpin Form of r(G4C2)exp in c9ALS/FTD Is Repeat-Associated Non-ATG Translated and a Target for Bioactive Small Molecules. Cell Chem Biol :
Sakae, Nobutaka; Bieniek, Kevin F; Zhang, Yong-Jie et al. (2018) Poly-GR dipeptide repeat polymers correlate with neurodegeneration and Clinicopathological subtypes in C9ORF72-related brain disease. Acta Neuropathol Commun 6:63
Mordes, Daniel A; Prudencio, Mercedes; Goodman, Lindsey D et al. (2018) Dipeptide repeat proteins activate a heat shock response found in C9ORF72-ALS/FTLD patients. Acta Neuropathol Commun 6:55
Pottier, Cyril; Zhou, Xiaolai; Perkerson 3rd, Ralph B et al. (2018) Potential genetic modifiers of disease risk and age at onset in patients with frontotemporal lobar degeneration and GRN mutations: a genome-wide association study. Lancet Neurol 17:548-558
Eftekharzadeh, Bahareh; Daigle, J Gavin; Kapinos, Larisa E et al. (2018) Tau Protein Disrupts Nucleocytoplasmic Transport in Alzheimer's Disease. Neuron 99:925-940.e7

Showing the most recent 10 out of 45 publications