Effect of fyn kinase driven inflammatory cytokine associated dopaminergic neurodegeneration and microglia activation in zebrafish.

The Alzheimer's Disease and Parkinson's Disease risk locus Fyn kinase is implicated in protein pathophysiology and NF-?B microglia inflammatory signaling. To investigate in vivo mechanisms of Fyn driven neurodegeneration, we built a zebrafish neural specific Gal4:UAS model of constitutively active FynY531F signaling. Using in vivo live imaging we demonstrate neural FynY531F expression leads to dopaminergic neuron loss and mitochondrial aggregation in 5 day larval brain. Gene expression analyses reveal reduction in neuroprotective genes, and elevated inflammatory cytokines Il-1ß, IL-12 and TNF-a and genes associated with oxidative stress. These phenotypes correlate with microglia activation in the larval brain. Chemical inhibition demonstrates dopaminergic neuron loss is dependent on Fyn and NF-?B/Caspase 1 signaling. We identify Stat3 activation as a novel downstream effector of Fyn signaling that acts synergistically with NF-?B in dopaminergic neuron degeneration. These results show Fyn drives neurodegeneration through NF-?B inflammatory signaling and Stat3 pathways. Activation of Stat3 provides a potential link from Fyn to mitochondrial dysfunction associated with dopaminergic neuron loss. Overall design: To investigate the role of fyn kinase in mediating neurodegeneration, we established the overexpression of constitutively active mutant FynY531F in zebrafish neurons.. We then performed gene expression analysis using data obtained from RNA -seq of three different lines, at 2 time points, 3dpf and 5dpf. Comparisons were made between 2 controls (+/+ and elav3:gal4) and fyn model (elav3:gal4;UAS:fynY531F) at both time points and model compared between both time points. Please note that the "_deg_all.txt" includes all deg's while "_deg.txt" includes statistically significant deg's.