Amyotrophic lateral sclerosis (ALS) is a late onset neurodegenerative disorder characterized by the loss of upper and lower motor neurons. FUS and TDP-43 are DNA/RNA binding proteins found to be mutated in both sporadic and familial forms of ALS. To investigate the pathogenesis of ALS caused by FUS/TLS mutations, we established a series of transgenic Drosophila lines that ectopically express human wild type and mutant FUS/TLS. Targeted expression of mutant, but not wild type FUS, in Drosophila eyes causes the formation of ubiquitinated aggregates and an external eye degenerative phenotype. Interestingly, ectopic expression of mutant FUS in motor neurons resulted in larval paralysis, pupal lethality, whereas wild type FUS expression had minimal effect. Mutant FUS localized to both the cytoplasm and nucleus, whereas wild type FUS localized only to the nucleus, suggesting that the cytoplasmic localization of FUS/TLS is required for toxicity. Furthermore, we found that deletion of the nuclear export signal strongly suppressed toxicity, suggesting that cytoplasmic localization is necessary for neurodegeneration. We found that expression of mutant FUS in the fly muscles leads to held-up wing phenotype, muscle degeneration and mitochondrial degeneration. We also found that mutating RNA binding residues of FUS strongly suppress mutant FUS toxicity in vivo. While doing an unbiased genetic screening, we discovered muscleblind as a novel modifier of mutant FUS toxicity. In our proposed studies, we will determine the role of mitochondrial functions in mediating FUS- related ALS and which functions of mitochondria are disrupted by the ALS causing mutations. We will systematically determine the role of RNA binding ability of FUS in causing ALS pathogenesis. We will also investigate if muscleblind regulates alternative splicing and sub- cellular distribution of FUS and contributes to the onset and progression of FUS-related ALS. Our proposed studies are expected to provide novel insights into the molecular mechanism of FUS-related ALS that would help in developing a therapeutic interventions for ALS for which currently no cure available.

Public Health Relevance

Determining factors responsible for causing accumulation of misfolded and toxic proteins will contribute to our understanding of molecular mechanisms of Lou Gehrig's disease and will help in developing an effective therapy since currently no treatment available. We developed a novel Drosophila model of FUS-related amyotrophic lateral sclerosis that recapitulates several key pathological features of human disease but molecular mechanism responsible of ALS is not well understood and our proposed research would increase our understanding of FUS and its interacting partners. Because there is considerable overlap between several neurodegenerative diseases at clinical and molecular level we expect that our findings will be relevant to the mission of the NIH and be broadly applicable to researchers studying molecular mechanisms of neurodegeneration.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Cellular and Molecular Biology of Neurodegeneration Study Section (CMND)
Program Officer
Gubitz, Amelie
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Pittsburgh
Schools of Medicine
United States
Zip Code
Anderson, Eric N; Gochenaur, Lauren; Singh, Aditi et al. (2018) Traumatic injury induces stress granule formation and enhances motor dysfunctions in ALS/FTD models. Hum Mol Genet 27:1366-1381
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
Guo, Lin; Kim, Hong Joo; Wang, Hejia et al. (2018) Nuclear-Import Receptors Reverse Aberrant Phase Transitions of RNA-Binding Proteins with Prion-like Domains. Cell 173:677-692.e20
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
Monahan, Zachary; Shewmaker, Frank; Pandey, Udai Bhan (2016) Stress granules at the intersection of autophagy and ALS. Brain Res 1649:189-200
Daigle, J Gavin; Krishnamurthy, Karthik; Ramesh, Nandini et al. (2016) Pur-alpha regulates cytoplasmic stress granule dynamics and ameliorates FUS toxicity. Acta Neuropathol 131:605-20
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

Showing the most recent 10 out of 11 publications