Development and characterization of a robust in vitro disease cell line to study tauopathies

Background Tauopathies, such as frontotemporal dementia (FTD) and Alzheimer’s dimentia (AD), are neurodegenerative diseases characterized by the pathological aggregation of paired helical filaments (PHFs) or neurofibrillary tangles (NFTs) within neurons and glia, leading to cell death1. PHFs and NFTs are formed by aggregation of hyperphosphorylated tau1. Mutations in the microtubule‐associated protein tau (MAPT) gene result in tauopathies. Moreover, FTD is a common clinical syndrome of 4 repeat (4R) tauopathies, as defined by aggregation of tau protein isoforms with four microtubule binding domains2. Here, we aimed to develop and characterize a physiologically relevant and robust in vitro FTD model, to aid the future development of FTD disease therapeutics. Method Using CRISPR‐Cas9 gene editing technology, familial mutations MAPT P301S and N279K underlying AD/FTD3 were engineered into an iPSC line that carries the opti‐oxTM technology and can rapidly be reprogrammed into glutamatergic neurons4. By means of immunocytochemistry we characterized b‐amyloid oligomer treated neurons, and neurons with the MAPT mutations to assess tau hyperphosphorylation. Result The CRISPR‐edited MAPT neurons can mature and show a healthy morphology. b‐amyloid oligomers (dose dependently) induce tau hyperphosphorylation in wild type glutamatergic neurons. Total tau expression is reduced in MAPT P301S homozygous and N279K heterozygous cells when compared to wild type cells. The MAPT P301S cells also show hyperphosphorylation for p‐tau 217, p‐tau202/205, and p‐tau404, and the N279K cells show hyperphosphorylation for p‐tau202/205, and p‐tau404. Conclusion The elevated p‐tau to total tau ratio measured by the immunocytochemistry assay indicates the potential of at least two cell lines as possible disease models to aid future research into developing AD/FTD disease therapeutics. References: 1. Silva MC, eLife, 2019 2. Seward ME, et al, 2013. Journal Cell Sci 126(5):1278‐1286 3. Hutton M, et al, 1998, Nature 393:702‐705 4. PawlowskiM, et al, 2017. Stem cell reports 8(4), 803‐812