Optogenetic Induction of TDP-43 Proteinopathy In Vivo (S32.005)

Objective: Aberrant protein aggregation is a common feature of many neurodegenerative diseases. We designed a novel in vivo model of amyotrophic lateral sclerosis (ALS) that provides unprecedented spatiotemporal control over disease TDP-43 aggregation dynamics using blue light. Background: Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease that leads to the death of motor neurons of the brain and spinal cord with no cure. It is characterized by extreme clinical and genetic heterogeneity, with between 15–40 different genes harboring causative mutations for the disease. Despite this complexity, nearly 97% of cases share the pathological hallmark of TDP-43 aggregation in the cytoplasm of affected neurons and glia, suggesting a conserved toxic mechanism that can be targeted therapeutically. We employed this method to understand how TDP-43 aggregation contributes to neurotoxicity. Design/Methods: We generated a construct of human TDP-43 connected to a light sensitive molecule that reversibly oligomerizes in response to blue light, hereby termed optoTDP43. This construct was inserted into the Drosophila genome in a site-specific manner. Using the GAL4/UAS system, we expressed this construct in various neuronal tissues and examined how aggregation dynamics influence neurotoxicity. Results: OptoTDP43 expressing flies appear phenotypically normal upon eclosion and show normal motor function. When exposed to a blue light stimulation paradigm, optoTDP43 aggregates in the Drosophila brain and exhibits features that recapitulate key aspects of pathology found in ALS patients. This includes a shift from the soluble to the insoluble fraction and N-terminal cleavage. Flies expressing optoTDP43 in motor neurons exhibit blue-light dependent motor dysfunction and neurodegeneration. Conclusions: OptoTDP43 exhibits blue light dependent aggregation and neurodegeneration in vivo. This model’s lack of reliance on overexpression to drive aggregation and toxicity may provide novel insight into the disease process and ALS pathobiology. Disclosure: Dr. Otte has nothing to disclose. Dr. Mann has nothing to disclose. Dr. Pandey has nothing to disclose. Dr. Donnelly has nothing to disclose.