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DeTure, M.

Publications and source records attributed to DeTure, M..

9 recordsLinked to original sources

TDP-43 subtypes shape transcriptomic signatures in Alzheimer's disease

TAR DNA-binding protein 43 (TDP-43) pathology frequently co-occurs with Tau neurofibrillary tangles (NFTs) and amyloid {beta} plaques in Alzheimers disease (AD), driving significant clinical heterogeneity. Whether TDP-43 engages autonomous molecular programs or instead amplifies Tau-driven neurodegeneration remains difficult to resolve, largely because these pathologies often co-occur. To separate these overlapping signatures, we generated regionally resolved transcriptomic profiles from cognitively normal controls (Controls), neuropathologically defined cohorts of AD, AD with limbic-predominant age-related TDP-43 encephalopathy (AD/LATE), and frontotemporal lobar degeneration (FTLD-TDP), categorizing them by their distinct TDP-43 subtypes (types and {beta} for AD/LATE; types A and B for FTLD-TDP). By integrating transcriptomic profiles with quantitative measures of phosphorylated TDP-43 (pTDP-43) and Tau (pTau), we separated pathology-associated signals within mixed disease contexts. We found that TDP-43 is linked to distinct transcriptomic programs in AD/LATE that are largely uncoupled from Tau burden and diverge from those observed in FTLD-TDP. These signatures showed regional specificity, with transcriptomic remodeling occurring in the amygdala across both diseases, whereas frontal cortex alterations were largely restricted to FTLD-TDP. Furthermore, by stratifying cases by TDP-43 morphological subtype, we unmasked specific biological trajectories, from immune activation to unique cellular vulnerabilities, that are not apparent in unstratified cohorts. Together, our findings provide a framework for decoupling mixed proteinopathies and demonstrate that TDP-43 shapes autonomous, subtype-dependent transcriptional landscapes in AD.

neuroscience↗

Neurodegeneration risk variants promote lysosomal TMEM106B fibrilaccumulation

Variants in TMEM106B and GRN, which encode lysosomal proteins, interact through unknown mechanisms to increase the risk of age-related cognitive decline and neurodegeneration. Here, we show that these variants converge on a single molecular intermediate: the cleaved intra-lysosomal fibril core of TMEM106B, a precursor to amyloid fibrils that accumulate in the aging brain. A protein-coding TMEM106B risk variant (p.T185) drives fibril core accumulation by impairing its degradation and GRN risk variants amplify this effect. Mice over-expressing the fibril core develop hallmarks of neurodegeneration, and cryo-electron tomography reveals intra-lysosomal fibrils in cultured neurons, mice, and diseased human brain. In GRN-mutation carriers, in whom fibril burden is greatest, fibrils extrude through ruptured lysosomal membranes. These findings identify intra-lysosomal TMEM106B fibrillization as a convergent neurodegeneration mechanism and potential therapeutic target.

cell biology↗

Integrative Epigenomic Landscape of Alzheimer's Disease Brains Reveals Oligodendrocyte Molecular Perturbations Associated with Tau

Alzheimers disease (AD) brains are characterized by neuropathologic and biochemical changes that are highly variable across individuals. Capturing epigenetic factors that associate with this variability can reveal novel biological insights into AD pathophysiology. We conducted an epigenome-wide association study of DNA methylation (DNAm) in 472 AD brains with neuropathologic measures (Braak stage, Thal phase, and cerebral amyloid angiopathy score) and brain biochemical levels of five proteins (APOE, amyloid-{beta} (A{beta})40, A{beta}42, tau, and p-tau) core to AD pathogenesis. Using a novel regional methylation (rCpGm) approach, we identified 5,478 significant associations, 99.7% of which were with brain tau biochemical measures. Of the tau-associated rCpGms, 93 had concordant associations in external datasets comprising 1,337 brain samples. Integrative transcriptome-methylome analyses uncovered 535 significant gene expression associations for these 93 rCpGms. Genes with concurrent transcriptome-methylome perturbations were enriched in oligodendrocyte marker genes, including known AD risk genes such as BIN1, myelination genes MYRF, MBP and MAG previously implicated in AD, as well as novel genes like LDB3. We further annotated the top oligodendrocyte genes in an additional 6 brain single cell and 2 bulk transcriptome datasets from AD and two other tauopathies, Picks disease and progressive supranuclear palsy (PSP). Our findings support consistent rCpGm and gene expression associations with these tauopathies and tau-related phenotypes in both bulk brain tissue and oligodendrocyte clusters. In summary, we uncover the integrative epigenomic landscape of AD and demonstrate tau-related oligodendrocyte gene perturbations as a common potential pathomechanism across different tauopathies.

genomics↗

Development and characterization of phospho-ubiquitin antibodies to monitor PINK1-PRKN signaling in cells and tissue

The selective removal of dysfunctional mitochondria, a process termed mitophagy, is critical for cellular health and impairments have been linked to aging, Parkinson disease, and other neurodegenerative conditions. A central mitophagy pathway is orchestrated by the ubiquitin (Ub) kinase PINK1 together with the E3 Ub ligase PRKN/Parkin. The decoration of damaged mitochondrial domains with phosphorylated Ub (p-S65-Ub) mediates their elimination though the autophagy system. As such p-S65-Ub has emerged as a highly specific and quantitative marker of mitochondrial damage with significant disease relevance. Existing p-S65-Ub antibodies have been successfully employed as research tools in a range of applications including western blot, immunocytochemistry, immunohistochemistry, and ELISA. However, physiological levels of p-S65-Ub in the absence of exogenous stress are very low, therefore difficult to detect and require reliable and ultrasensitive methods. Here we generated and characterized a collection of novel recombinant, rabbit monoclonal p-S65-Ub antibodies with high specificity and affinity in certain applications that allow the field to better understand the molecular mechanisms and disease relevance of PINK1-PRKN signaling. These antibodies may also serve as novel diagnostic or prognostic tools to monitor mitochondrial damage in various clinical and pathological specimens.

neuroscience↗

Genome-wide association study of brain biochemical phenotypes reveals distinct genetic architecture of Alzheimer's Disease related proteins

Alzheimers disease (AD) is neuropathologically characterized by amyloid-beta (A{beta}) plaques and neurofibrillary tangles. Main protein components of these hallmarks include A{beta}40, A{beta}42, tau, phospho-tau and APOE. With the exception of the APOE-{varepsilon}4 variant, genetic risk factors associated with brain biochemical measures of these proteins have yet to be characterized. We performed a genome-wide association study in brains of 441 AD patients for quantitative levels of these proteins collected from three distinct fractions reflecting soluble, membrane-bound and insoluble biochemical states. We identified 123 genome-wide significant associations at seven novel loci and the APOE locus. Genes and variants at these loci also associate with multiple AD- related measures, regulate gene expression, have cell-type specific enrichment, and roles in brain health and other neuropsychiatric diseases. Pathway analysis identified significant enrichment of shared and distinct biological pathways. Although all biochemical measures tested reflect proteins core to AD pathology, our results strongly suggest that each have unique genetic architecture and biological pathways that influence their specific biochemical states in the brain. Our novel approach of deep brain biochemical endophenotype GWAS has implications for pathophysiology of proteostasis in AD that can guide therapeutic discovery efforts focused on these proteins.

genetics↗

Amyloid fibrils in frontotemporal lobar degeneration with TDP-43 inclusions are composed of TMEM106B, rather than TDP-43

FTLD is the third most common neurodegenerative condition, following only Alzheimers and Parkinsons diseases. FTLD typically presents in 45-64-year-olds with behavioral changes or progressive decline of language skills. The subtype FTLD-TDP is characterized by certain clinical symptoms and pathological neuronal inclusions detected by TDP-43 immunoreactivity. Here, we extracted amyloid fibrils from brains of four patients, representing four out of five FTLD-TDP subclasses and determined their near-atomic resolution structures by cryo-EM. Unexpectedly, all amyloid fibrils examined are composed of a 135-residue C-terminal fragment of TMEM106B, a lysosomal membrane protein previously implicated as a genetic risk factor for FTLD-TDP. In addition to TMEM106B fibrils, abundant non-fibrillar aggregated TDP-43 is present, as revealed by immunogold labeling. Our observations confirm that FTLD-TDP is an amyloid-involved disease and suggest that amyloid involvement in FTLD-TDP is of protein TMEM106B, rather than of TDP-43.

molecular biology↗

Single-cell profiling of the human primary motor cortex in ALS and FTLD

Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are two devastating and fatal neurodegenerative conditions. While distinct, they share many clinical, genetic, and pathological characteristics1, and both show selective vulnerability of layer 5b extratelencephalic-projecting cortical populations, including Betz cells in ALS2,3 and von Economo neurons (VENs) in FTLD4,5. Here, we report the first high resolution single-cell atlas of the human primary motor cortex (MCX) and its transcriptional alterations in ALS and FTLD across ~380,000 nuclei from 64 individuals, including 17 control samples and 47 sporadic and C9orf72-associated ALS and FTLD patient samples. We identify 46 transcriptionally distinct cellular subtypes including two Betz-cell subtypes, and we observe a previously unappreciated molecular similarity between Betz cells and VENs of the prefrontal cortex (PFC) and frontal insula. Many of the dysregulated genes and pathways are shared across excitatory neurons, including stress response, ribosome function, oxidative phosphorylation, synaptic vesicle cycle, endoplasmic reticulum protein processing, and autophagy. Betz cells and SCN4B+ long-range projecting L3/L5 cells are the most transcriptionally affected in both ALS and FTLD. Lastly, we find that the VEN/Betz cell-enriched transcription factor, POU3F1, has altered subcellular localization, co-localizes with TDP-43 aggregates, and may represent a cell type-specific vulnerability factor in the Betz cells of ALS and FTLD patient tissues.

neuroscience↗

Role of molecular polymorphism in defining tau filament structures in neurodegenerative diseases

Misfolding and aggregation of tau protein is implicated in many neurodegenerative diseases that are typified by the presence of large, filamentous tau inclusions. The aggregation of tau in human brain is disease-specific with characteristic filaments defining the neuropathology. An understanding of how identical tau isoforms aggregate into disparate filament morphologies in phenotypically distinct tau-related diseases remains elusive. Here, we determine the structure of a brain-derived twisted tau filament in progressive supranuclear palsy and compare it to a dissimilar tau fold found in corticobasal degeneration. While the tau filament core in both diseases is comprised of residues 274 to 380, molecular-level polymorphism exists. Potential origins of the molecular polymorphism, such as noncovalent cofactor binding, are identified and predicted to modulate tau filament structures in the brain.

biophysics↗

Leveraging selective hippocampal vulnerability among Alzheimer's disease subtypes reveals a novel tau binding partner SERPINA5

Selective vulnerability is a central concept to the myriad of devastating neurodegenerative disorders. Although hippocampus and cortex are selectively vulnerable in Alzheimers disease (AD), the degree of involvement lies along a spectrum that we previously defined as AD subtypes revealing distinct clinical correlates. To operationalize heterogeneity of disease spectrum, we classified corticolimbic patterns of neurofibrillary tangles to capture extreme and representative phenotypes. We combined bulk RNA sequencing with digital pathology to examine hippocampal vulnerability in AD. Using a multidisciplinary approach, we uncovered disease-relevant hippocampal gene expression changes. Biological relevance was prioritized using machine learning and several levels of human validation. This resulted in five genes highly predictive of neuropathologically diagnosed AD: SERPINA5, RYBP, SLC38A2, FEM1B, and PYDC1. Deeper investigation revealed SERPINA5 to be a novel tau binding partner that may represent a "tipping point" in the dynamic maturity of neurofibrillary tangles. Our study highlights the importance of embracing heterogeneity of the human brain to yield promising gene candidates as exampled by SERPINA5.

neuroscience↗