Senktide blocks aberrant RTN3 interactome to retard memory decline and tau pathology in social isolated Alzheimer’s disease mice

Sporadic or late-onset Alzheimer’s disease(LOAD)accounts for more than 95%of Alzheimer’s disease(AD)cases without any family history.Although genome-wide association studies have identified associated risk genes and loci for LOAD,numerous studies suggest that many adverse environmental factors,such as social isolation,are associated with an increased risk of dementia.However,the underlying mechanisms of social isolation in AD progression remain elusive.In the current study,we found that 7 days of social isolation could trigger pattern separation impairments and presynaptic abnormalities of the mossy fibre-CA3 circuit in AD mice.We also revealed that social isolation disrupted histone acetylation and resulted in the downregulation of 2 dentate gyrus(DG)-enriched miRNAs,which simultaneously target reticulon 3(RTN3),an endoplasmic reticulum protein that aggregates in presynaptic regions to disturb the formation of functional mossy fibre boutons(MFBs)by recruiting multiple mitochondrial and vesicle-related proteins.Interestingly,the aggregation of RTN3 also recruits the PP2A B subunits to suppress PP2A activity and induce tau hyperphosphorylation,which,in turn,further elevates RTN3 and forms a vicious cycle.Finally,using an artificial intelligence-assisted molecular docking approach,we determined that senktide,a selective agonist of neurokinin3 receptors(NK3R),could reduce the binding of RTN3 with its partners.Moreover,application of senktide in vivo effectively restored DG circuit disorders in socially isolated AD mice.Taken together,our findings not only demonstrate the epigenetic regulatory mechanism underlying mossy fibre synaptic disorders orchestrated by social isolation and tau pathology but also reveal a novel potential therapeutic strategy for AD.

Engineering human spinal microphysiological systems to model opioid-induced tolerance

pioids are commonly used for treating chronic pain.However,with continued use,they may induce tolerance and/or hyperalgesia,which limits therapeutic efficacy.The human mechanisms of opioid-induced tolerance and hyperalgesia are significantly understudied,in part,because current models cannot fully recapitulate human pathology.Here,we engineered novel human spinal microphysiological systems(MPSs)integrated with plug-and-play neural activity sensing for modeling human nociception and opioid-induced tolerance.Each spinal MPS consists of a flattened human spinal cord organoid derived from human stem cells and a 3D printed organoid holder device for plug-and-play neural activity measurement.We found that the flattened organoid design of MPSs not only reduces hypoxia and necrosis in the organoids,but also promotes their neuron maturation,neural activity,and functional development.We further demonstrated that prolonged opioid exposure resulted in neurochemical correlates of opioid tolerance and hyperalgesia,as measured by altered neural activity,and downregulation ofμ-opioid receptor expression of human spinal MPSs.The MPSs are scalable,cost-effective,easy-to-use,and compatible with commonly-used well-plates,thus allowing plug-and-play measurements of neural activity.We believe the MPSs hold a promising translational potential for studying human pain etiology,screening new treatments,and validating novel therapeutics for human pain medicine.

The β-catenin/YAP signaling axis is a key regulator of melanoma-associated fibroblasts

β-catenin is a multifunctional protein that plays crucial roles in embryonic development,physiological homeostasis,and a wide variety of human cancers.Previously,we showed that in vivo targeted ablation ofβ-catenin in melanoma-associated fibroblasts after melanoma formation significantly suppressed tumor growth.However,when the expression ofβ-catenin was ablated in melanoma-associated fibroblasts before tumor initiation,melanoma development was surprisingly accelerated.How stromalβ-catenin deficiency leads to opposite biological effects in melanoma progression is not completely understood.Here,we report thatβ-catenin is indispensable for the activation of primary human stromal fibroblasts and the mediation of fibroblast-melanoma cell interactions.Using coimmunoprecipitation and proximity ligation assays,we identified Yes-associated protein(YAP)as an importantβ-catenin-interacting partner in stromal fibroblasts.YAP is highly expressed in the nuclei of cancer-associated fibroblasts(CAFs)in both human and murine melanomas.Mechanistic investigation revealed that YAP nuclear translocation is significantly modulated by Wnt/β-catenin activity in fibroblasts.Blocking Wnt/β-catenin signaling in stromal fibroblasts inhibited YAP nuclear translocation.In the absence of YAP,the ability of stromal fibroblasts to remodel the extracellular matrix(ECM)was inhibited,which is consistent with the phenotype observed in cells withβ-catenin deficiency.Further studies showed that the expression of ECM proteins and enzymes required for remodeling the ECM was suppressed in stromal fibroblasts after YAP ablation.Collectively,our data provide a new paradigm in which theβ-catenin-YAP signaling axis regulates the activation and tumor-promoting function of stromal fibroblasts.