Alzheimer & Parkinson

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease linked to exposure to repetitive head impacts (RHI), yet little is known about its pathogenesis. Applying two single-cell whole-genome sequencing methods to hundreds of neurons from prefrontal cortex of 15 individuals with CTE and 4 with RHI without CTE, we revealed increased somatic single-nucleotide variants in CTE, exhibiting a pattern previously reported in Alzheimer's disease (AD). Furthermore, we discovered high burdens...

Rethinking Alzheimer's disease through the lens of myelin.

Dysregulated lipid metabolism promotes persistent microglial activation and neuroinflammation in Alzheimer's disease (AD), but the underlying pathogenic mechanisms remain to be elucidated, and druggable targets remain to be identified. Here we found that multifunctional enzyme type 2 (MFE-2), the key enzyme regulating fatty acid β-oxidation in the peroxisome, was downregulated in the microglia of humans with AD and AD model mice. Microglia-specific ablation of MFE-2 drove microglial...

CONCLUSIONS: We offer a gene-centric perspective to understand spatially coordinated expression between neighboring cells. Our method only requires the gene expression and cell location matrices to find cross-expressing gene pairs. The R package is available at https://github.com/gillislab/CrossExpression .

Spatial transcriptomics enables detailed mapping of gene expression within tissues, revealing spatial organization of cellular and molecular processes. However, generating such data is costly and technically challenging, and analysis requires advanced bioinformatics skills. Although public datasets are growing, existing databases offer limited tools for interactive exploration and cross-sample comparison. Here, we introduce DeepSpaceDB (www.deepspacedb.com), a next-generation spatial...

The low in vivo yield of midbrain dopaminergic (mDA) neurons and uncertain lineage fates of donor cells following transplantation impede clinical application of human pluripotent stem cell (hPSC)-based cell therapy for Parkinson's disease (PD). We developed a three-dimensional (3D) differentiation method, SphereDiff, to generate high-purity mDA progenitors (mDAPs), leading to a significant enrichment of mDA neurons post transplantation. Grafted mDA neurons fully restored dopamine levels and...

Clonally expanded CD8^(+) T cells may contribute to Alzheimer's disease (AD) pathology through interactions with brain-resident cells. However, the functional impact of AD-specific T cell receptor (TCR) clonotypes remains unclear. Here, we demonstrate that CD8^(+) T cells undergo clonal expansion in early-stage AD mouse models, App^(NL-G-F) and 5xFAD, and that their depletion reduces amyloid plaque accumulation. Expanded TCR-expressing CD8^(+) T cells preferentially infiltrate the brain,...

The biological mechanisms underlying the increased prevalence of Alzheimer's disease (AD) in women remain undefined. While previous case/control studies have identified sex-biased molecular pathways, the sex-specific relationships between gene expression and AD endophenotypes, particularly involving sex chromosomes, are underexplored. With bulk transcriptomic data across 3 brain regions from 767 decedents, we investigated sex-specific associations between gene expression and post-mortem...

Hippocampal degeneration is a feature of both normal aging and Alzheimer's disease (AD). Prior to macroscopic degeneration, microstructural changes occur such as demyelination, iron deposition, or subtle atrophy, which can be characterized in vivo using MRI. We topographically mapped measures of microstructure and macrostructure across the unfolded surface of the hippocampus in 224 healthy older adults at risk for AD (aged 57 to 87) and 37 younger adults (aged 18 to 37). We describe three...

Tau aggregation into amyloid fibrils is linked to the development of neurodegenerative diseases, including Alzheimer's disease (AD). The molecular processes driving aggregation in disease are still being uncovered, highlighting the need for innovative tools to study aggregation reactions. Here, we introduce FibrilPaint1 as a tool to measure the size of Tau amyloid fibrils in fluids, from early aggregation stages to mature fibrils. FibrilPaint1 is a 22mer peptide with exciting properties: i)...

Altered β-amyloid (Aβ) homeostasis is a critical event triggering the shift from healthy aging to Alzheimer disease (AD) through the overproduction and impaired clearance of Aβ peptides. The Aβ-degrading enzymes (ADEs) are a collective group of proteases that normally promote clearance to counteract Aβ-induced neurodegeneration. We previously discovered that the beta-site amyloid precursor protein cleaving enzyme 1 is an atypical ADE that produces the nontoxic fragment Aβ34 by recognizing 40- or...

Sleep alterations have long been associated with Alzheimer's disease (AD), but whether it is an early symptom or only develops later in the pathological progression remains unknown. To study this, 5xFAD heterozygous (Het) mice, a transgenic model of amyloid overexpression, and wild-type (WT) littermates at 1, 2, 3, 4 and 6 months of age were assessed within instrumented home cages to noninvasively score 3-state sleep using respirations and gross body movements during the dark cycle. Progressive...

The "eye-brain axis" refers to the dynamic system of interactions between the eyes and the brain, collectively encompassing the visual signal transmission and integration pathways. The eyes and the brain exhibit structural and functional synergy, and visual dysfunction not only impairs information processing within the eye but also induces structural and functional remodeling of the central nervous system (CNS) via the eye-brain axis. For instance, the effects of glaucoma on the visual cortex...

Parkinson's disease (PD) is a progressive neurodegenerative disorder primarily marked by the degeneration of dopaminergic neurons and pathological α-synuclein (α-syn) accumulation. Although insulin-degrading enzyme (IDE) has been implicated in both type 2 diabetes mellitus and amyloid-protein clearance, its precise relevance to PD pathogenesis remains unclear. In this study, we show that IDE expression is reduced in the nigrostriatal region of aging homozygous A53T α-syn mice and in...

Golgi fragmentation is an early and common feature of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and Alzheimer's disease (AD). However, whether a shared mechanism drives Golgi fragmentation across different neurodegenerative conditions remains unclear. Here, we identify the E3 ubiquitin-protein ligase Itchy homolog (ITCH) as a key regulator of proteotoxicity through its role in inducing Golgi fragmentation. Disease-associated accumulation of ITCH promotes...

The acidic pH of lysosomes required for function is established by the electrogenic V-ATPase proton pump. How lysosomes prevent hyper-acidification by the pump is not well established. Recently, the Parkinson's disease (PD)-associated protein TMEM175 was proposed as a H+-selective channel to leak protons to counter over-acidification. We rigorously address key findings and predictions of this model and show that, in the lysosome, TMEM175 predominantly conducts K+ and is not a H+-selective...

While circadian rhythm disruption may promote neurodegenerative disease, the impact of aging and neurodegenerative pathology on circadian gene expression patterns in different brain cell types remains unknown. Here we used a translating ribosome affinity purification to identify the circadian translatomes of astrocytes, microglia and bulk tissue in healthy mouse cortex and in the settings of amyloid-β plaque pathology or aging. We show that glial circadian translatomes are highly...

In Alzheimer's disease (AD), hyperactivated microglia produce inflammatory mediators that contribute to neuroinflammation and neuronal damage. Amyloid precursor protein (APP), a transmembrane protein expressed in many cell types, including neurons and microglia, plays a critical role in AD pathogenesis via its secretase-mediated processing to release the C-terminal 99-residue transmembrane fragment (C99) that is further cleaved to yield amyloid-β peptides. Voltage-gated proton channels (Hv1)...

Parkinson disease (PD) and other α-synucleinopathies are characterized by the intracellular aggregates of SNCA/α-synuclein (synuclein, alpha) thought to spread via cell-to-cell transmission. To understand the contributions of various brain cells to the spreading of SNCA pathology, we examined the metabolism of SNCA aggregates in neuronal and glial cells. In neurons, while the full-length SNCA rapidly disappeared following SNCA pre-formed-fibril (PFF) uptake, truncated SNCA accumulated with a...

Recent advances in single-cell transcriptomics have led to the identification of disease-associated microglia (DAM) as a distinct, conserved microglia state associated with mouse models of Alzheimer's disease (AD) and amyotrophic lateral sclerosis, and with aging. DAM are characterized by downregulation of homeostatic genes and upregulation of lipid metabolism and phagocytosis genes, including key risk factors for AD in humans. Although characterized in models of AD, whether DAM acts as...