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Amyotrophic lateral sclerosis (ALS), or Lou Gehrig’s Disease, is a late-onset neurodegenerative disorder characterized by loss of cortical and spinal motor neurons with no known cure to-date. Mutations in genes including human Fused in Sarcoma (h-FUS), (caz in Drosophila), is a DNA/RNA binding protein, plays a crucial role in regulating nucleocytoplasmic RNA transport, alternative splicing and has known to be associated with causing ALS. It has been shown earlier that targeted misexpression of h-FUS or its mutants R518K and R521C (using GAL4/UAS system), in Drosophila melanogaster (a.k.a fruit fly) eye, causes accumulation of ubiquitinated proteins which enhances ALS mediated neurodegeneration. In order to 1. understand this process better, 2. search for genetic modifier of ALS and 3. to elucidate the mechanism of action by which FUS mediates neurodegeneration, we used this fruit fly eye model of ALS (as genetic machinery is conserved from fruit flies to humans) and, checked the effect of modulating the levels of Hippo (growth regulatory pathway, highly conserved) and c-Jun N-terminal Kinase (JNK) signaling in h-FUS or its mutants R518K, R521C background and checked for their resultant phenotypes in 1. larval eye-antennal imaginal discs and 2. adult fly eyes. Results from our studies confirms that, Hippo (hpo), is a newly identified genetic modifier of ALS mediated neurodegeneration, and that activation of Hippo or JNK pathway in FUS background worsens FUS mediated neurodegeneration while their in-activation significantly rescues FUS mediated neurodegeneration in fly eye. The results were confirmed by checking 1. cell death (TUNEL assay), 2. axonal targeting (functionality of photoreceptor neurons) from the retina to the brain, 3. Q-PCR, Western blot analysis, and 4. by checking how downstream targets of Hippo and JNK pathway gets regulated in these backgrounds. Our data presents a model that upregulation of FUS or its mutants, results in activation of Hippo pathway, which further activates c-Jun N-terminal Kinase (JNK) signaling and causes neurodegeneration/ photoreceptor neuronal cell death which ultimately causes ALS. This study helps in understanding the molecular genetic mechanism behind ALS associated h-FUS mediated neurodegeneration and finding effective, reliable future therapeutic targets that can modify the neurodegenerative behavior of ALS.
Madhuri Kango-Singh, Amit Singh
Primary Advisor's Department
Stander Symposium poster
"Role of Hippo Signaling in Amyotrophic Lateral Sclerosis (ALS) disease using Drosophila eye model" (2019). Stander Symposium Posters. 1449.