Abstract:   Cellular kinases play a central role in protein aggregation in dementia and neurodegeneration and their involvement in inflammatory signaling in Alzheimer’s Disease (AD) and related neurodegenerative diseases (ADRD) is now emerging. The Src family member Fyn kinase mediates AD amyloid b and tau protein pathophysiology. More recently Fyn was identified as a Parkinson’s Disease (PD) risk locus and in vitro has been shown to regulate microglia PKC-d/NF-kb inflammatory signaling in response to a-synuclein aggregate uptake. While protein aggregation and microglia activation reinforce neuroinflammation, the cellular mechanism at the intersection of these pathways is incompletely understood. An in vivo cell type-specific model of Fyn signaling is needed to reveal new insights into mechanisms driving microglia activation, and to provide an effective genetic tool to identify novel Fyn effectors of neurodegeneration. In my talk, I will discuss two projects to examine in vivo the mechanism of Fyn signaling in microglia activation and neurodegeneration. First, using confocal live imaging and gene expression analysis, I demonstrated our neuronal Gal4, UAS: Fyn zebrafish PD model drives dopaminergic neuron loss in the 3-5 day larval brain diencephalon. This loss correlates with microglia activation and elevated expression of inflammatory cytokines IL-1b, IL12b, and TNFa. Chemical inhibition studies showed that Fyn-driven neurodegeneration and cytokine expression were mediated by the canonical PKC-d/NF-kb/caspase-1 pathway. This work also identified the PKA pathway as a novel downstream effector in the mechanism of Fyn signaling. In a second project, I used our GeneWeld CRISPR precision knock-in strategy to isolate loss of function and Cre-regulated conditional alleles in the zebrafish caspase-1 homolog caspa. Together with our CRISPR generated mpeg1.1-2A-KalTA4 knockin, these novel caspa genetic tools will be used to examine the cell-autonomous requirement of canonical PKC-d/NF-kb/caspase-1 signaling in Fyn-driven microglia activation. Ongoing experiments to identify PKA targets mediating Fyn-driven neurodegeneration and to investigate Fyn signaling in microglia activation will be presented.