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Sivanantharajah, L.

Publications and source records attributed to Sivanantharajah, L..

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The Drosophila wing is a high-throughput and versatile screening tool for Tau-mediated disease mechanisms and drug discovery.

Tau protein contributes to microtubule stability, which is disrupted in Alzheimers disease and other Tauopathies. In these diseases, Tau molecules become hyperphosphorylated, misfolded and aggregated, propagating pathology across the brain. Studies dissecting disease mechanisms or screening disease-modifying therapies rely on animal models that unveil pathogenic events in vivo but also take several weeks or months to complete. Here we describe a versatile experimental paradigm that yields results in days and yet offers all the advantages of a genetically tractable in vivo system: the Drosophila wing disc. Mimicking neurotoxicity, human Tau expression causes cell death in the wing disc leading to quantifiable phenotypes in the adult wing. The neuroprotective peptide NAP ameliorates Tau toxicity in this system, validating it as a cost-effective drug screening tool. Phenocopying adult neurons, Tau toxicity in the wing disc is exacerbated by simulating hyper-phosphorylation and prevented by suppressing aggregation. Additionally, we show that the wing disc can dissect disease mechanisms that underpin clinically relevant Tau variants. Thus, the wing disc offers an in vivo experimental paradigm for fast and efficient exploration of disease mechanism and screening.

neuroscience↗

Aggregation promoting sequences rather than phosphorylation are essential for Tau-mediated toxicity in Drosophila

BackgroundDisease-modifying therapies for tauopathies like Alzheimers disease have targeted Tau hyperphosphorylation and aggregation, as both pathological manifestations are implicated in Tau-mediated toxicity. However, the relative contributions of these pathology-linked changes to Tau neurotoxicity remain unclear. MethodsLeveraging the genetic tractability of Drosophila, we generated multiple inducible human Tau transgenes with altered phosphorylation status and/or aggregation propensity. Their individual and combined impact was tested in vivo by quantifying Tau accumulation and neurodegenerative phenotypes in the aging fly nervous system. ResultsWe report that phospho-mimicking Tau (hTau2N4RE14) induced profound neurodegeneration, supporting a neurotoxic role for phosphorylation. However, when we rendered hTau2N4RE14 aggregation incompetent, by deleting the 306VQIVYK311 motif in the microtubule-binding region, neurotoxicity was abolished. Moreover, a peptide inhibitor targeting this motif efficaciously reduced Tau toxicity in aging Drosophila. ConclusionNeurodegeneration mediated by Tau hyperphosphorylation is gated via at least one aggregation-mediating motif on the protein. This highlights the primacy of blocking Tau aggregation in therapy, perhaps without the need to clear phosphorylated species.

neuroscience↗