ALS is a late-onset progressive neurodegenerative disease caused by degeneration of motor neurons, and a disease hallmark is the accumulation of ubiquitin-positive aggregates in neuronal cytoplasm. FUS was identified as genes mutated in both familial and sporadic forms of ALS. In fact, a subset of patients with frontotemporal dementia (FTD) show FUS pathology. FUS, similar to TDP-43, is an RNA binding protein implicated in multiple aspects of RNA metabolism, including splicing, trafficking, and translation. The precise mechanisms of mutated FUS in ALS pathogenesis are not known. To understand the molecular mechanisms of FUS-mediated neurodegeneration, we developed cellular (mammalian primary neuronal and patient-derived iPSC motor neuron) and Drosophila models that recapitulate key features of human disease including cytoplasmic mislocalization, neuromuscular junction defects, locomotor dysfunctions, reduced life span, perturbed stress granule dynamics and toxicity. We discovered muscleblind and drosha as unexpected and novel modifiers of mutant FUS toxicity. MBNL proteins, highly conserved from lower organisms to vertebrates, have been implicated in many neurodegenerative disorders, such as myotonic dystrophy and CAG repeat diseases. The long-term goal is to identify modifiers of FUS toxicity and understand their molecular mechanisms using mammalian cell culture and Drosophila models. The objective of our current application is to determine how muscleblind and drosha modulate FUS-mediated toxicity in Drosophila and FUS iPSC motor neurons. We hypothesize that muscleblind and drosha regulate RNA splicing, SG dynamics and miRNA biogenesis that is perturbed by pathogenic mutations in FUS. We will examine the impact of muscleblind and drosha on cellular and molecular pathologies in FUS-associated neurodegeneration. We expect to dissect the molecular pathways that could be exploited for developing therapeutic interventions for ALS/FTD patients.

Public Health Relevance

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are devastating human neurodegenerative diseases for which currently no cure available. Current project is aimed to elucidate the molecular mechanisms of novel genetic modifiers of FUS toxicity which in turn would help in identifying pathways perturbed in ALS and related disorders

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
2R01NS081303-06A1
Application #
9763021
Study Section
Molecular Neurogenetics Study Section (MNG)
Program Officer
Gubitz, Amelie
Project Start
2013-04-15
Project End
2024-02-29
Budget Start
2019-04-01
Budget End
2020-02-29
Support Year
6
Fiscal Year
2019
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Pediatrics
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15260
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Kim, Sang Hwa; Stiles, Shannon G; Feichtmeier, Joseph M et al. (2018) Mutation-dependent aggregation and toxicity in a Drosophila model for UBQLN2-associated ALS. Hum Mol Genet 27:322-337
Marrone, Lara; Poser, Ina; Casci, Ian et al. (2018) Isogenic FUS-eGFP iPSC Reporter Lines Enable Quantification of FUS Stress Granule Pathology that Is Rescued by Drugs Inducing Autophagy. Stem Cell Reports 10:375-389
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Crippa, Valeria; Cicardi, Maria Elena; Ramesh, Nandini et al. (2016) The chaperone HSPB8 reduces the accumulation of truncated TDP-43 species in cells and protects against TDP-43-mediated toxicity. Hum Mol Genet 25:3908-3924
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Scaramuzzino, Chiara; Casci, Ian; Parodi, Sara et al. (2015) Protein arginine methyltransferase 6 enhances polyglutamine-expanded androgen receptor function and toxicity in spinal and bulbar muscular atrophy. Neuron 85:88-100
Casci, Ian; Pandey, Udai Bhan (2015) A fruitful endeavor: modeling ALS in the fruit fly. Brain Res 1607:47-74
Wen, Xinmei; Tan, Wenzhi; Westergard, Thomas et al. (2014) Antisense proline-arginine RAN dipeptides linked to C9ORF72-ALS/FTD form toxic nuclear aggregates that initiate in vitro and in vivo neuronal death. Neuron 84:1213-25

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