P4‐257: ACTIVITY‐DEPENDENT TRANSLATION AT THE SYNAPSE IS DYSFUNCTIONAL PRE‐SYMPTOMATICALLY IN A TRANSGENIC MOUSE MODEL OF ALZHEIMER'S DISEASE

pathological PTM is phosphorylation with phosphorylated forms of tau (AD), TDP-43 (ALS, FTLD) and alpha-synuclein (PD) all associated with disease, whereas decreased phosphorylation on huntingtin (HD) is thought to be protective. In addition, the role of cell signalling pathways, mostly regulated by kinase/phosphatase cascades, is increasingly being recognised as modulating key aspects of neurodegeneration such as re-activation of cell cycle in neuronal cells and activation of immune cells such as microglia and astrocytes. Accordingly, there is a strong rationale to develop and apply global phosphorylation profiling to neuronal cell cultures and brain tissues used in neurodegenerative disease research.Methods:We have recently reported SysQuant, a global phosphoproteomic workflow that employs isobaric TandemMass Tags (TMT) and differential chromatography tomeasure fractions of both enriched phosphopeptides and the un-enriched nonphosphorylated peptides derived from tryptic digestion of tumour cell lysates of up to 10 samples in a single mass spectrometry experiment. The current SysQaunt workflow can quantitate over 25,000 unique phosphorylation sites on more than 7,000 individual proteins. In addition a further 7,000 proteins can be quantified for which there is no evidence of phosphorylation. Results: When applied to frozen brain tissue from a recently developed mouse model of human tauopathy (TMHT Mouse, QPS Austria) treated with vehicle or vehicle + kinase inhibitors, we were able to demonstrate significant, potentially protective effects on the phosphorylation of aggregating proteins as well as regulation of key pathways such as glycolysis/gluconeogenesis, calcium signalling, oxidative phosphorylation, citrate cycle along with all major neurodegenerative KEGG pathways. Further details will be provided at the meeting. Conclusions: By using a TMT 10plex labelling strategy we were able to generate a detailed, quantitative phosphoproteomic map for 3 x 3 x 3 animals treated with vehicle or one of two kinase inhibitors from hippocampus, cortex and rest of brain regions in approximately 8 weeks.