Biology subjects

Edbauer, D.

Publications and source records attributed to Edbauer, D..

8 recordsLinked to original sources

bioRxiv2025

Direct binding of TDP-43 and Tau drives their co-condensation, but suppresses Tau fibril formation and seeding

Neuronal Tau aggregates are a hallmark of Alzheimers disease (AD), but more than half of the patients exhibit additional TDP-43 inclusions and some have co-aggregates of both proteins. The presence of Tau/TDP-43 co-pathology is associated with increased disease severity, although the causal relationship remains unclear. Here we demonstrate that Tau and TDP-43 mutually promote each others condensation through direct interaction in vitro, forming irregularly shaped or multiphasic co-condensates with lower TDP-43 mobility, but higher Tau dynamics. While Tau promotes TDP-43 aggregation in vitro, TDP-43 suppresses formation of Tau fibrils and instead causes formation of oligomeric Tau and Tau/TDP-43 species. These co-assemblies hinder Tau seeding in a biosensor assay specific for proteopathic Tau seeds. Consistent with this data, SarkoSpin extracts from AD brains with Tau/TDP-43 co-pathology exhibit reduced Tau seeding compared to Tau-only AD brains. In contrast, patient-derived extracts from AD brains with Tau/TDP-43 co-pathology are highly potent in seeding TDP-43 neoaggregates in a TDP-43 reporter cell line. Our results suggest that direct interaction of TDP-43 and Tau may suppress Tau pathology, while promoting TDP-43 pathology. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=133 SRC="FIGDIR/small/662960v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@1ed5dfaorg.highwire.dtl.DTLVardef@b4ef07org.highwire.dtl.DTLVardef@b8dbe8org.highwire.dtl.DTLVardef@6d9b49_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2025

Comparative CRISPRi screens reveal a human stem cell dependence on mRNA translation-coupled quality control

The translation of mRNA into proteins in multicellular organisms needs to be carefully tuned to changing proteome demands in development and differentiation, and defects in translation often have a disproportionate impact in distinct cell types. Here we used inducible CRISPR interference screens to compare the essentiality of genes with functions in mRNA translation in human induced pluripotent stem cells (hiPSC) and hiPSC-derived neural and cardiac cells. We find that core components of the mRNA translation machinery are broadly essential, but the consequences of perturbing translation-coupled quality control factors are highly cell type-dependent. Human stem cells critically depend on pathways that detect and rescue slow or stalled ribosomes, and on the E3 ligase ZNF598 to resolve a novel type of ribosome collisions at translation start sites on endogenous mRNAs with highly efficient initiation. Our findings underscore the importance of cell identity for deciphering the molecular mechanisms of translational control in metazoans.

molecular biology↗

bioRxiv2024

Enhanced legumain activity links progranulin deficiency to TDP-43 pathology in frontotemporal lobar degeneration

Loss-of-function mutations in GRN are a major cause of frontotemporal lobar degeneration (FTLD) with TDP-43-positive inclusions. Progranulin (PGRN) loss leads to lysosomal dysfunction, microglial hyperactivation, and TDP-43 deposition, yet the underlying pathomechanism remains unknown. We demonstrate that PGRN slows the maturation and limits the proteolytic activity of the lysosomal protease legumain (LGMN). Accordingly, LGMN activity is strongly elevated in Grn knockout (ko) mice, in human induced pluripotent stem cell-derived GRN ko microglia, and in FTLD-GRN patients brain. Secreted microglial LGMN is internalized by neurons, where it mediates pathological processing of TDP-43, which is prevented by selective LGMN inhibition. In contrast, AAV-mediated overexpression of LGMN in mouse brains promotes TDP-43 processing, the aggregation of phosphorylated TDP-43 and increases plasma neurofilament light chain (NfL), a marker for neuronal loss. Our findings identify LGMN as a link between PGRN haploinsufficiency and TDP-43 pathology in FTLD-GRN and suggest LGMN as a therapeutic target.

neuroscience↗

bioRxiv2023

Multiomic ALS signatures highlight sex differences and molecular subclusters and identify the MAPK pathway as therapeutic target

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease and lacks effective disease-modifying treatments. Here, we performed a multiomic analysis of the prefrontal cortex of 51 patients with sporadic ALS and 50 control subjects, as well as four transgenic mouse models of C9orf72-, SOD1-, TDP-43-, and FUS-ALS to characterize early and sex-specific disease mechanisms in ALS. Integrated analyses of transcriptomes, (phospho)proteomes, and miRNAomes revealed more pronounced changes in males. We identified transcriptome-based human ALS subclusters driven by the immune response, ECM, mitochondrial respiration, and RNA metabolism. The molecular signatures of human subclusters were reflected in specific mouse models. Individual and integrative multiomics analysis highlighted the mitogen-activated protein kinase pathway as an early disease-relevant mechanism. Its modulation by trametinib in vitro and in vivo validated that mitogen-activated protein kinase kinase 2 is a promising therapeutic target with beneficial effects in females.

neuroscience↗

bioRxiv2023

Rescue of FTLD-associated TDP-43 pathology and neurodegeneration by peripheral AAV-mediated expression of brain-penetrant progranulin

Progranulin (PGRN) haploinsufficiency is a major risk factor for frontotemporal lobar degeneration with TDP-43 pathology (FTLD-GRN). Multiple therapeutic strategies are in clinical development to restore PGRN levels in the CNS, including gene therapy. However, a limitation of current gene therapy approaches aimed to alleviate FTLD-associated pathologies may be their inefficient brain exposure and biodistribution. We therefore developed an adeno-associated virus (AAV) targeting the liver (L) to achieve sustained peripheral expression of a transferrin receptor (TfR) binding, brain-penetrant (b) PGRN variant (AAV(L):bPGRN) in two mouse models of FTLD-GRN, namely Grn knockout and GrnxTmem106b double knockout mice. This therapeutic strategy avoids potential safety and biodistribution issues of CNS-administered AAVs while maintaining sustained levels of PGRN in the brain following a single dose. AAV(L):bPGRN treatment reduced several FTLD-GRN associated disease pathologies including severe motor function deficits, aberrant TDP-43 solubility and phosphorylation, dysfunctional protein degradation, lipid metabolism, gliosis and neurodegeneration in the brain. Translatability of our findings was confirmed in a novel human in vitro model using co-cultured human induced pluripotent stem cell (hiPSC)-derived microglia lacking PGRN and TMEM106B and wild-type hiPSC-derived neurons. As in mice, aberrant TDP-43, lysosomal dysfunction and neuronal loss were ameliorated after treatment with exogenous TfR-binding protein transport vehicle fused to PGRN (PTV:PGRN). Together, our studies suggest that peripherally administered brain-penetrant PGRN replacement strategies can ameliorate FTLD-GRN relevant phenotypes including TDP-43 pathology, neurodegeneration and behavioral deficits. Our data provide preclinical proof of concept for the use of this AAV platform for treatment of FTLD-GRN and potentially other CNS disorders. One sentence summaryPeripheral AAV-mediated delivery of brain-penetrant PGRN rescues TDP-43 pathology, neurodegeneration and motor phenotypes in FTLD-GRN models.

neuroscience↗

bioRxiv2021

Disease-linked TDP-43 hyperphosphorylation suppresses TDP-43 condensation and aggregation

Post-translational modifications (PTMs) have emerged as key modulators of protein phase separation and have been linked to protein aggregation in neurodegenerative disorders. The major aggregating protein in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), the RNA-binding protein TDP-43, is hyperphosphorylated in disease on several C-terminal serine residues, which is generally believed to promote TDP-43 aggregation. Here, we show that hyperphosphorylation by Casein kinase 1{delta} or C-terminal phosphomimetic mutations surprisingly reduce TDP-43 phase separation and aggregation and render TDP-43 condensates more liquid-like and dynamic. Multi-scale simulations reveal reduced homotypic interactions of TDP-43 low complexity domains through enhanced solvation of phosphomimetic residues. Cellular experiments show that phosphomimetic substitutions do not affect nuclear import or RNA regulatory functions of TDP-43, but suppress accumulation of TDP-43 in membrane-less organelles and promote its solubility in neurons. We propose that TDP-43 hyperphosphorylation may be a protective cellular response to counteract TDP-43 aggregation.

biochemistry↗

bioRxiv2021

Gel-like inclusions of C-terminal fragments of TDP-43 sequester and inhibit proteasomes in neurons

TDP-43 inclusions enriched in C-terminal fragments of ~25kDa ("TDP-25") are associated with neurodegeneration in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Here, we analyzed gain-of-function mechanisms of TDP-25 combining cryo-electron tomography, proteomics and functional assays. TDP-25 inclusions are amorphous with gel-like biophysical properties and sequester proteasomes adopting exclusively substrate-processing conformations. This leads to proteostasis impairment, further enhanced by pathogenic mutations. These findings bolster the importance of proteasome dysfunction in ALS/FTD.

neuroscience↗

bioRxiv2017

RNA-dependent intergenerational inheritance of enhanced synaptic plasticity after environmental enrichment

Physical exercise in combination with cognitive training is known to enhance synaptic plasticity and lower the risk for various complex diseases including Alzheimers disease. Here we show that exposure of adult male mice to an environmental enrichment paradigm leads to long-lasting enhancement of synaptic plasticity that is also passed on to the next generation. We show that the effect is mediated through sperm RNA and is explained by microRNAs 212/132. In conclusion, our study reports intergenerational inheritance of an acquired cognitive benefit and points to specific microRNAs as candidates mechanistically involved in this type of transmission.

neuroscience↗