Alzheimer & Parkinson

Increasing evidence indicates skeletal muscle function is associated with cognition. Muscle-secreted protease Cathepsin B (Ctsb) is linked to memory in animals and humans, but has an unclear role in neurodegenerative diseases. To address this question, we utilized an AAV-vector-mediated approach to express Ctsb in skeletal muscle of APP/PS1 Alzheimer's disease (AD) model mice. Mice were treated with Ctsb at 4 months of age, followed by behavioral analyses 6 months thereafter. Here we show that...

Aging is the strongest risk factor for cognitive decline and Alzheimer's disease (AD), yet the mechanisms underlying brain aging and their modulation by pharmacological interventions remain poorly defined. The hippocampus, essential for learning and memory, is particularly vulnerable to metabolic stress and inflammation. Canagliflozin (Cana), an FDA-approved sodium-glucose co-transporter 2 inhibitor (SGLT2i) for type 2 diabetes, extends lifespan in male but not female mice, but its impact on...

While progressive cognitive decline is the defining feature of Alzheimer's disease (AD), many patients also develop prominent neuropsychiatric symptoms, including anxiety and depression. The circuit-level mechanisms underlying these distinct symptom domains remain poorly understood, and treatments that address both cognitive and noncognitive aspects of AD are limited. Here, we identify anatomically, molecularly, and functionally distinct subpopulations of supramammillary (SuM) neurons that...

Alzheimer's disease (AD) has long resisted effective treatments due to its pathological heterogeneity and cell-type-specific regulatory changes. In this issue of Cell, Li et al. leverage single-cell RNA sequencing and drug repurposing to propose a promising combination therapy, validated through real-world evidence and mouse models, that targets multiple AD-relevant cell types.

Alzheimer's disease is a specific neurodegenerative disorder, distinct from normal aging, with a growing unmet medical need. It is characterized by the accumulation of amyloid plaques in the brain, primarily consisting of amyloid beta (Aβ) fibrils. Therapeutic antibodies can slow down the disease, but are associated with potential severe side effects, motivating the development of small molecules to halt disease progression. This study investigates the interaction between the clinical drug...

Neuroimaging and machine learning are advancing research into the mechanisms of biological aging. In this field, 'brain age gap' has emerged as a promising magnetic resonance imaging-based biomarker that quantifies the deviation between an individual's biological and chronological age of the brain. Here we conducted an in-depth genomic analysis of the brain age gap and its relationships with over 1,000 health traits. Genome-wide analyses in up to 56,348 individuals unveiled a heritability of...

Mitochondrial homeostasis relies on a tight balance between mitochondrial biogenesis and degradation. Although mitophagy is one of the main pathways involved in the clearance of damaged or old mitochondria, its coordination with mitochondrial biogenesis is poorly characterized. Here, by unbiased approaches including last-generation liquid chromatography coupled to mass spectrometry and transcriptomics, we identify the protein phosphatase PP2A-B55α/PPP2R2A as a Parkin-dependent regulator of...

Complex diseases often exhibit sex dimorphism in morbidity and prognosis, many of which are age-related. However, the underlying mechanisms of sex-dimorphic aging remain foggy, with limited studies across multiple tissues. We systematically analyzed ~17,000 transcriptomes from 35 human tissues to quantitatively evaluate the individual and combined contributions of sex and age to transcriptomic variations. We discovered extensive sex dimorphisms during aging with distinct patterns of change in...

Huntington disease (HD) is a neurodegenerative disease caused by the expression of a mutant form of HTT (huntingtin; mHTT), caused by an abnormal expansion of polyglutamine in HTT. In HD, macroautophagy/autophagy dysfunction can cause mHTT accumulation. Moreover, the promotion of autophagy is considered a therapeutic strategy for the treatment of HD. ZKSCAN3 (zinc finger with KRAB And SCAN domains 3) has been identified as a transcriptional repressor of TFEB (transcription factor EB), a master...

Microglial states underlying Alzheimer's disease (AD) have been well characterized in animal models and human samples, yet their regulation remains elusive. In this issue of Neuron, Zhu et al.¹ uncover Adgrg1, which governs a protective microglia phenotype through MYC activation.

Cellular deconvolution estimates cell-type fractions from bulk transcriptomic data, but current methods often overlook cell type-specific expression varying across samples, discrepancies between bulk and single-cell data, or lack guidance on reference data selection and integration. Therefore, we present BLEND, a hierarchical Bayesian method that leverages multiple single-cell reference datasets to perform cellular deconvolution. BLEND estimates cellular fractions accurately by learning the most...

Intercellular nanotubular networks mediate material exchange, but their existence in neurons remains to be explored in detail. We identified long, thin dendritic filopodia forming direct dendrite-dendrite nanotubes (DNTs) in mammalian cortex. Super-resolution microscopy in dissociated neurons revealed DNTs' actin-rich composition and dynamics, enabling long-range calcium ion (Ca^(2+)) propagation. Imaging and machine learning-based analysis validated in situ DNTs as anatomically distinct from...

Integrating single-cell RNA sequencing with Genome-Wide Association Studies (GWAS) can uncover cell types involved in complex traits and disease. However, current methods often lack scalability, interpretability, and robustness. We present seismic, a framework that computes a novel specificity score capturing both expression magnitude and consistency across cell types and introduces influential gene analysis, an approach to identify genes driving each cell type-trait association. Across over...

The accumulation of intracellular aggregates of Tau protein is one main hallmark of Alzheimer's disease (AD) and is the consequence of Tau conformational changes, increased phosphorylation, and self-association to form fibrillar aggregates. This pathological process prevents the physiological interaction of Tau with microtubules to the detriment of the structural integrity of neurons. In healthy cells, aberrant protein misfolding and aggregation are counteracted by chaperone proteins whose...

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On the basis of extensive mechanistic research over three decades, Parkinson disease (PD) and related synucleinopathies have been proposed to be combined proteinopathies and lipidopathies. Evidence strongly supports a physiological and pathogenic interplay between the disease-associated protein α-synuclein and lipids, with a demonstrable role for lipids in modulating PD phenotypes in the brain. Here, we refine this hypothesis by proposing PD to be a disease specifically involving metabolic...

Parkinson's disease (PD) is a neurodegenerative condition characterized by the presence of intraneuronal aggregates containing fibrillar ɑ-synuclein known as Lewy bodies. These large end-stage species are formed by smaller soluble protein nanoscale assemblies, often termed oligomers, which are proposed as early drivers of pathogenesis. Until now, this hypothesis has remained controversial, at least in part because it has not been possible to directly visualize nanoscale assemblies in human brain...

Extracellular Tau determines the progression of Alzheimer's disease, yet therapeutic strategies targeting it are hindered by poor brain delivery and limited clearance. Here we developed a Tau-clearing cell therapy based on monocytes functionalized with a high-affinity Tau-specific aptamer. The aptamer was covalently conjugated to the surface of monocytes (derived from bone marrow leucocytes and cultured under monocyte-inducing conditions) via bioorthogonal chemistry without affecting their...

Meningeal lymphatic vessels (MLVs) have been identified to associate with various neurological diseases, such as traumatic brain injury (TBI), Alzheimer's disease (AD), Parkinson's disease, multiple sclerosis, and brain tumors. Damage to MLVs can exacerbate the pathological progression of these diseases and significantly impede therapeutic efficacy. Therefore, targeted repair of the damaged MLVs has emerged as an innovative strategy for treating these central nervous system (CNS) diseases. In...

The conversion of proteins into insoluble fibrillar aggregates known as amyloid occurs in a wide variety of diseases, e.g., Alzheimer's disease, amyotrophic lateral sclerosis, systemic transthyretin amyloidosis, and multisystem atrophy. There are more than 60 disease-associated amyloid-forming proteins, and amyloid formation can occur sporadically or can be induced or accelerated by genetic mutations. This Review discusses structural mechanisms by which genetic changes promote amyloid formation...