Selective neuronal vulnerability to protein aggregation is found in many neurodegenerative diseases including Alzheimer's disease (AD). Understanding the molecular origins of this selective vulnerability is therefore of fundamental importance. Tau protein aggregates have been found in manuscriptClick here to access/download;manuscript;Manuscript_Final submission.docx Click here to view linked References Wolframin (WFS1)-expressing excitatory neurons in the entorhinal cortex, one of the earliest affected regions in AD. The role of WFS1 in Tauopathies and its levels in tau pathology-associated neurodegeneration, however, is largely unknown. Here we report WFS1 deficiency is associated with increased tau pathology and neurodegeneration, whereas overexpression of WFS1 reduces those changes. We also find that WFS1 interacts with tau protein and controls the susceptibility to tau pathology. Furthermore, chronic ER stress-and autophagy-lysosome pathway (ALP)associated genes are enriched in WFS1-high excitatory neurons in human AD at early Braak stages.The protein levels of ER stress-and autophagy-lysosome pathway (ALP)-associated proteins are changed in tau transgenic mice with WFS1 deficiency, while overexpression of WFS1 reverses those changes. This work demonstrates a possible role for WFS1 in the regulation of tau pathology and neurodegeneration via chronic ER stress and the downstream ALP. Our findings provide insights into mechanisms that underpin selective neuronal vulnerability, and for developing new therapeutics to protect vulnerable neurons in AD.

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Background Pathological tau accumulates in patients with Alzheimer’s disease (AD) and related tauopathies. However, it remains unclear why specific neuronal subtypes and brain regions are vulnerable to pathological tau in early AD. Recently we found excitatory neurons expressing the Wolframin (WFS1) in the entorhinal cortex and the CA1 of hippocampus are particularly vulnerable to pathological tau in tau transgenic mice and human AD. However, the role of WFS1 in mediating this selective neuronal vulnerability is unknown. Method The tau aggregates in live cells were imaged as individual tiles and stitched via the Zeiss Observer 7 fluorescent microscope, and then the area with tau aggregates in each stitched image was quantitated by Image J. The tau pathology in mouse brain was visualized by MC1‐positive and conformation‐dependent tau via the immunofluroscent staining. The protein interaction between WFS1 and tau was measured by the Duolink Proximity ligation assay (PLA) and co‐immunoprecipitation (CO‐IP) assay. Result Here we reported that overexpression of human WFS1 significantly reduced DS9 tau seeding in SH‐SY5Y cells stably transfected with P301S mutant tau, while overexpression of mutant P724L WFS1 did not. Also, overexpression of human WFS1 significantly reduced exogenous tau aggregation in primary mouse mixed neurons treated with P301S tau‐YFP lentivirus, while overexpression of mutant WFS1 did not. Furthermore, the heterozygotes of PS19 tau;NestinCre/+; Wfs1f/+ brain‐specific knock‐out mice and PS19 tau;Wfs1+/‐ knock‐out mice have much more tau pathology in the Dentate gyrus, CA1 and entorhinal cortex compared with PS19 tau and PS19 tau;Wfs1f/+ mice. The homozygotes of PS19 tau;NestinCre/+;Wfs1f/f brain‐specific knock‐out mice and PS19 tau;Wfs1‐/‐ knock‐out mice have even more tau pathology than those heterozygotes. We further identified that WFS1 interacts with both total tau and pathological tau in primary cultured neurons, wild‐type and tau transgenic mice, and human non‐AD and AD cases. The interaction is first enhanced as tau pathology increases, however, it is reduced as tau pathology further increases. Conclusion Taken together, we demonstrate that deficiency of Wfs1 increases vulnerability to pathological tau in vitro and in vivo, indicating WFS1 may be a therapeutic target for preventing or delaying the tau pathology in AD.

BackgroundAlzheimer disease (AD) and traumatic brain injury (TBI) are two devastating brain disorders with complex relationships. Growing evidence supports that early or middle life of TBI may be a risk factor for developing late‐life AD and AD‐related dementias (ADRD). Tau hyperphosphorylation and gliosis may serve as a causative link between TBI and AD as well as ADRD. We have recently identified BCL2 associated athanogene 3 (BAG3) as a hub gene of regulating tau protein homeostasis. The protein level of BAG3 is significantly reduced in neurons, but it is increased in astrocytes of human AD compared to controls. We hypothesized that overexpression of BAG3 in neurons would attenuate tau hyperphosphorylation and gliosis induced by TBI.MethodWe injected 500 nL AAV9‐hSYN1‐eGFP‐2A‐hBAG3‐WPRE or AAV9‐hSYN1‐eGFP‐WPRE (control AAV9) into the hippocampal CA1 and DG regions of C57BL6/J and htau knock‐in mice. These mice were subjected to TBI surgery (controlled cortical impact, velocity: 3.00 m/s, depth: 0.8 mm, dwell time: 200 ms) three months post the injection. We then performed behavioral tests (open‐field test, Y‐maze, and Morris Water Maze) on these mice one month after the CCI surgery. Following the behavioral tests, we collected the brain tissues and performed the immunofluorescent staining of ptau (PHF1, pS396/404 tau), BAG3, IBA‐1 (microglia/macrophage marker) and GFAP (astrocyte marker) on fixed mouse brain floating sections.ResultTBI increased the immunoreactivity of PHF1, IBA‐1, GFAP and astrocytic BAG3, whereas reducing neuronal BAG3 compared to sham C57BL6/J and htau knock‐in mice. Furthermore, the immunoreactivity of BAG3 increased, while PHF1, IBA‐1 and GFAP decreased in the ipsilateral hippocampus after the injection of AAV9‐BAG3 compared to those TBI mice injected with control AAVs. Continued immunofluorescent staining and quantification for AAV9‐BAG3‐ and control AAV9‐injected mice is currently ongoing, as is behavior data quantification.ConclusionTBI induces tau hyperphosphorylation, microglia activation and reactive astrocytes, while reducing neuronal BAG3 in C57BL6/J and htau knock‐in mice. Neuronal overexpression of BAG3 can significantly attenuate tau hyperphosphorylation and gliosis induced by TBI. Our data suggests that targeting neuronal BAG3 may be a therapeutic strategy for preventing or reducing intra‐neuronal tau aggregates and gliosis found in TBI and TBI‐associated AD and ADRD.