title: Biochemical investigation of Tau protein phosphorylation status and its solubility properties in Drosophila.
abstract: Tau hyperphosphorylation and insoluble aggregate formation are two cellular features of tauopathies. However, the contribution of Tau protein hyperphosphorylation and its aggregation to Tau pathology still remain controversial. Overexpression of human tau transgenes in the Drosophila eye is toxic and causes neuronal degeneration. We showed that human Tau protein was phosphorylated by endogenous protein kinases in flies, and overexpression of either GSK3beta or Cdk5 enhanced tau-induced toxicity. Using a dominant-negative approach, we showed that kinase activity is important for the enhancement of tau-induced toxicity. Interestingly, such enhancement was accompanied with hyperphosphorylation and alteration of protein solubility properties of Tau. This situation was reminiscent of that observed in pre-tangle neurons in tauopathies patients. We also observed age-dependent Tau aggregate formation in aged transgenic flies. In summary, tau-induced toxicity is enhanced when the human Tau protein undergoes hyperphosphorylation, and we further demonstrated that aging contributes to Tau aggregate formation. Our data also underscore the utilization of transgenic Drosophila Tau models for the studies of pre-tangle events in tauopathies.
authors.affiliation: Department of Biochemistry and Molecular Biotechnology Programme, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
authors.forename: Katy Wing-Kam
authors.initials: KW
authors.lastname: Chau
authors.forename: Wood-Yee
authors.initials: WY
authors.lastname: Chan
authors.forename: Pang Chui
authors.initials: PC
authors.lastname: Shaw
authors.forename: Ho-Yin Edwin
authors.initials: HY
authors.lastname: Chan
mesh_terms: D000375:Aging; D000818:Animals; D030801:Animals, Genetically Modified; D051360:Cyclin-Dependent Kinase 5 / Q000096:biosynthesis; D004330:Drosophila; D029721:Drosophila Proteins / Q000096:biosynthesis; D005123:Eye / Q000378:metabolism; D020869:Gene Expression Profiling; D038362:Glycogen Synthase Kinase 3 / Q000096:biosynthesis; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D018021:Lithium Chloride / Q000494:pharmacology; D010766:Phosphorylation; D012995:Solubility; D014921:Wings, Animal / Q000378:metabolism; D016875:tau Proteins / Q000378:metabolism* / Q000633:toxicity
chemical_list: D029721:Drosophila Proteins; D016875:tau Proteins; D051360:Cyclin-Dependent Kinase 5; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C080335:Sgg protein, Drosophila; D038362:Glycogen Synthase Kinase 3; D018021:Lithium Chloride