Project description:The glymphatic movement of fluid through the brain powerfully clears metabolic waste. We observed multisensory 40 Hz stimulation promotes the influx of cerebrospinal fluid and the efflux of interstitial fluid in the cortex of the 5XFAD mouse model of Alzheimer’s disease, which was associated with increased aquaporin-4 polarization along astrocytic endfeet, dilated meningeal lymphatic vessels, and amyloid accumulation in cervical lymph nodes. Inhibiting glymphatic clearance abolished the removal of amyloid by multisensory 40 Hz stimulation. Using chemogenetic manipulation and a genetically encoded sensor for neuropeptide signaling, we found VIP+ interneurons facilitate glymphatic clearance by regulating arterial pulsatility. Our findings establish novel mechanisms to recruit the glymphatic system to remove brain amyloid.
Project description:Amyloids are fibrous protein aggregates associated with age-related diseases. While these aggregates are typically described as irreversible and pathogenic, some cells utilize reversible amyloid-like structures that serve important functions. The RNA-binding protein Rim4 forms amyloid-like assemblies that are essential for translational control during S. cerevisiae meiosis. Rim4 amyloid-like assemblies are disassembled in a phosphorylation-dependent manner at meiosis II onset. By investigating Rim4 clearance, we elucidate co-factors that mediate clearance of amyloid-like assemblies in a physiological setting. We demonstrate that yeast 14-3-3 proteins bind to Rim4 assemblies and facilitate their subsequent phosphorylation and timely clearance. Furthermore, distinct 14-3-3 proteins play non-redundant roles in facilitating phosphorylation and clearance of amyloid-like Rim4. Additionally, we find that 14-3-3 proteins contribute to global protein aggregate homeostasis. Based on the role of 14-3-3 proteins in aggregate homeostasis and their interactions with disease-associated assemblies, we propose that these proteins may protect against pathological protein aggregates.
Project description:Neuroinflammation is thought to contribute to the pathogenesis of Alzheimer’s disease (AD), yet numerous studies have demonstrated a beneficial role for neuroinflammation in amyloid plaque clearance. We have previously shown that sustained expression of IL-1β in the hippocampus of APP/PS1 mice decreases amyloid plaque burden independent of recruited CCR2+ myeloid cells, suggesting resident microglia as the main phagocytic effectors of IL-1β-induced plaque clearance. To date, however, the mechanisms of IL-1β-induced plaque clearance remain poorly understood. To determine whether IL-1β-induced plaque clearance is due to enhanced microglial phagocytosis of Aβ, APP/PS1 mice induced to express mature human IL-1β in the hippocampus via adenoviral transduction were treated with the Aβ fluorescent probe methoxy-X04 (MX04) and microglial internalization of Aβ was analyzed by flow cytometry and immunohistochemistry. We found that resident microglia (CD45loCD11b+) constituted >70% of the MX04+ cells in both control and IL-1β-treated conditions, and that <10% of MX04+ cells were recruited myeloid cells (CD45hiCD11b+). However, we found that IL-1β treatment did not augment the percentage of MX04+ microglia nor the quantity of Aβ internalized by individual microglia. Instead, we found that IL-1β treatment resulted in a significant increase in the total number of MX04+ microglia in the hippocampus due to IL-1β-induced proliferation. Consistent with these results, transcriptomic analyses revealed very similar gene expression profiles between MX04+ and MX04- microglia, indicating IL-1β does not drive enhanced expression of phagocytosis-related genes. By contrast, IL-1β treatment was associated with large-scale changes in the expression of genes related to proliferation, immune function and inflammation. Together, these studies demonstrate that IL-1β induces microglial proliferation and the expression of genes involved in inflammatory immune functions that may be related to Aβ clearance.
Project description:We have generated Gas6 knock-down YTN16 cells using the shRNA system to specifically target Growth arrest-specific 6 (Gas6), a gene of interest in mouse gastric cancer cells. Additionally, we aimed to determine the differences in gene expression levels between YTN16 cells and YTN16 cells with Gas6 knock-down (shGas6) through RNA-sequencing analysis.