Biology subjects

Neubert, T. A.

Publications and source records attributed to Neubert, T. A..

9 recordsLinked to original sources

bioRxiv2026

Pathological tau leads to network hyperexcitability through neuronal-subtype-specific functional impairment

Pathological tau disrupts neuronal activity and brain function in Alzheimer s disease and other tauopathies. However, the underlying mechanisms for neuronal network dysfunction remain largely unknown. Using human inducible pluripotent stem cell (iPSC) - derived neurons, we show that the familial MAPT P301L mutation leads to neuronal network hyperexcitability. Imbalanced excitation and inhibition were attributable to neuronal subtype-specific tau pathology that was associated with different alterations of tau interactomes in excitatory versus inhibitory neurons. Suppressing enhanced excitatory synaptic transmission or blocking Ca2+ influx resulting from enhanced P301L tau/AHNAK interaction in inhibitory neurons rescued the neuronal network hyperexcitability. This study expands our understanding on how disease-causing tau mutations alter the excitatory/inhibitory balance, leading to network dysfunction in human neurons.

neuroscience↗

bioRxiv2026

A single-domain antibody targets aggregation-prone region of α-synuclein to reduce synucleinopathy, rescue neurodegeneration and improve function

Synucleinopathies are a group of neurodegenerative disorders characterized by the accumulation of aggregated -synuclein (-syn), including Parkinsons disease, Dementia with Lewy Bodies, and Multiple System Atrophy. These diseases are marked by locomotor and non-motor impairments, as well as mitochondrial dysfunction and the loss of dopaminergic (DA) neurons. We have developed several anti--syn single-domain antibodies (sdAbs) and demonstrated the diagnostic imaging potential of two of them and the acute therapeutic benefit of one in clearing -syn in a mouse model. However, whether these sdAbs can suppress -syn-mediated neuronal loss and locomotor impairment in vivo remains unclear. We evaluated the therapeutic potential of five anti--syn sdAbs to clear pathological -syn in mouse neuronal culture and then demonstrated their in vivo efficacy in a Drosophila model of synucleinopathy. The sdAbs differed in their efficacy to lower levels of phospho-serine 129 -syn, prevent loss of DA neurons, alleviate mitochondrial dysfunction, improve motor function, and prolong survival in synucleinopathy flies. The most effective sdAb, 2H1, has not been reported before. It binds strongly to the aggregation prone region of -syn and robustly improves all these disease parameters. Additionally, that sdAb is associated with -syn in the fly neurons, as shown through proximity dependent turboID biotinylation assays. The sdAb-turboID also biotinylated -syn-associated proteins involved in synapse/vesicle trafficking pathways, pinpointing the location of their intracellular interaction. Our findings provide an insight into the therapeutic mechanism of action of these sdAbs and strongly support their clinical development.

neuroscience↗

bioRxiv2024

VLK drives extracellular phosphorylation of EphB2 to govern the EphB2-NMDAR interaction and injury-induced pain

Phosphorylation of hundreds of protein extracellular domains is mediated by two kinase families, yet the significance of these kinases is underexplored. Here, we find that the presynaptic release of the tyrosine directed-ectokinase, Vertebrate Lonesome Kinase (VLK/Pkdcc), is necessary and sufficient for the direct extracellular interaction between EphB2 and GluN1 at synapses, for phosphorylation of the ectodomain of EphB2, and for injury-induced pain. Pkdcc is an essential gene in the nervous system, and VLK is found in synaptic vesicles, and is released from neurons in a SNARE-dependent fashion. VLK is expressed by nociceptive sensory neurons where presynaptic sensory neuron-specific knockout renders mice impervious to post-surgical pain, without changing proprioception. VLK defines an extracellular mechanism that regulates protein-protein interaction and non-opioid-dependent pain in response to injury. One-Sentence SummarySynaptic protein-protein interactions and pain are regulated by the presynaptic release of the extracellular kinase VLK in the spinal cord.

neuroscience↗

bioRxiv2023

Knockout of cardiolipin synthase disrupts postnatal cardiac development by inhibiting the maturation of mitochondrial cristae

BackgroundCardiomyocyte maturation requires a massive increase in respiratory enzymes and their assembly into long-lived complexes of oxidative phosphorylation (OXPHOS). The molecular mechanisms underlying the maturation of cardiac mitochondria have not been established. MethodsTo determine whether the mitochondria-specific lipid cardiolipin is involved in cardiac maturation, we created a cardiomyocyte-restricted knockout (KO) of cardiolipin synthase (Crls1) in mice and studied the postnatal development of the heart. We also measured the turnover rates of proteins and lipids in cardiolipin-deficient flight muscle from Drosophila, a tissue that has mitochondria with high OXPHOS activity like the heart. ResultsCrls1KO mice survived the prenatal period but failed to accumulate OXPHOS proteins during postnatal maturation and succumbed to heart failure at the age of 2 weeks. Turnover measurements showed that the exceptionally long half-life of OXPHOS proteins is critically dependent on cardiolipin. ConclusionsCardiolipin is essential for the postnatal maturation of cardiomyocytes because it allows mitochondrial cristae to accumulate OXPHOS proteins to a high concentration and to shield them from degradation.

developmental biology↗

bioRxiv2023

Modulation of GPR133 (ADGRD1) Signaling by its Intracellular Interaction Partner Extended Synaptotagmin 1 (ESYT1)

GPR133 (ADGRD1) is an adhesion G protein-coupled receptor that signals through Gs and is required for growth of glioblastoma (GBM), an aggressive brain malignancy. The regulation of GPR133 signaling is incompletely understood. Here, we use proximity biotinylation proteomics to identify ESYT1, a Ca2+-dependent mediator of endoplasmic reticulum-plasma membrane bridge formation, as an intracellular interactor of GPR133. ESYT1 knockdown or knockout increases GPR133 signaling, while its overexpression has the opposite effect, without altering GPR133 levels in the plasma membrane. The GPR133-ESYT1 interaction requires the Ca2+-sensing C2C domain of ESYT1. Thapsigargin-mediated increases in cytosolic Ca2+ relieve signaling-suppressive effects of ESYT1 by promoting ESYT1-GPR133 dissociation. ESYT1 knockdown or knockout in GBM impairs tumor growth in vitro, suggesting functions of ESYT1 beyond the interaction with GPR133. Our findings suggest a novel mechanism for modulation of GPR133 signaling by increased cytosolic Ca2+, which reduces the signaling-suppressive interaction between GPR133 and ESYT1 to raise cAMP levels.

cell biology↗

bioRxiv2022

PTK7 is a positive allosteric modulator of GPR133 (ADGRD1) signaling in GBM

GPR133 (ADGRD1), an adhesion G protein-coupled receptor, supports growth of glioblastoma, a brain malignancy. We demonstrated that GPR133 is intramolecularly cleaved, and that dissociation of its N-terminal and C-terminal fragments (NTF and CTF) at the plasma membrane correlates with increased receptor signaling. However, how the extracellular interactome of GPR133 in glioblastoma modulates signaling remains unknown. Here, we use affinity purification and mass spectrometry to identify extracellular binding partners of GPR133 in patient-derived glioblastoma cells. We show that the transmembrane protein PTK7 binds the GPR133 NTF and its expression in trans increases GPR133 signaling. This effect requires the intramolecular cleavage of GPR133 and PTK7s anchoring in the plasma membrane. The GPR133-PTK7 interaction facilitates orthosteric activation of GPR133 by soluble peptide mimicking the endogenous tethered Stachel agonist, suggesting PTK7 binding allosterically enhances accessibility of GPR133s orthosteric Stachel binding pocket. GPR133 and PTK7 are expressed in adjacent cells in glioblastoma, where their knockdown phenocopies each other. We propose that this novel ligand-receptor interaction is relevant to the pathogenesis of glioblastoma, as well as physiological processes in several tissues.

cell biology↗

bioRxiv2021

Comparing synaptic proteomes across seven mouse models for autism reveals molecular subtypes and deficits in Rho GTPase signaling

Impaired synaptic function is a common phenotype in animal models for autism spectrum disorder (ASD), and ASD risk genes are enriched for synaptic function. Here we leverage the availability of multiple ASD mouse models exhibiting synaptic deficits and behavioral correlates of ASD and use quantitative mass spectrometry with isobaric tandem mass tagging (TMT) to compare the hippocampal synaptic proteomes from 7 mouse models. We identified common altered cellular and molecular pathways at the synapse, including changes in Rho family small GTPase signaling, suggesting that it may be a point of convergence in ASD. Comparative analyses also revealed clusters of synaptic profiles, with similarities observed among models for Fragile X syndrome (Fmr1 knockout), PTEN hamartoma tumor syndrome (Pten haploinsufficiency), and the BTBR+ model of idiopathic ASD. Opposing changes were found in models for cortical dysplasia focal epilepsy syndrome (Cntnap2 knockout), Phelan McDermid syndrome (Shank3 InsG3680), Timothy syndrome (Cacna1c G406R), and ANKS1B syndrome (Anks1b haploinsufficiency), which were similar to each other. We propose that these clusters of synaptic profiles form the basis for molecular subtypes that explain genetic heterogeneity in ASD despite a common clinical diagnosis. Drawn from an internally controlled survey of the synaptic proteome across animal models, our findings support the notion that synaptic dysfunction in the hippocampus is a shared mechanism of disease in ASD, and that Rho GTPase signaling may be an important pathway leading to disease phenotypes in autism.

neuroscience↗

bioRxiv2020

Dysregulation of the de novo proteome accompanies pathology progression in the APP/PS1 mouse model of Alzheimer's disease

Alzheimers disease (AD) is an age-related neurodegenerative disorder, but neuropathological changes in AD begin years before memory impairment. Investigation of the early molecular abnormalities in AD might offer innovative opportunities to target memory impairment prior to its onset. Decreased protein synthesis plays a fundamental role in AD, yet the consequences for cellular function remain unknown. We hypothesize that alterations in the de novo proteome drive early metabolic changes in the hippocampus that persist throughout AD progression. Using a combinatorial amino acid tagging approach to selectively label newly synthesized proteins, we found that the de novo proteome is disturbed in APP/PS1 mice prior to pathology development, affecting the synthesis of multiple components of synaptic, lysosomal and mitochondrial pathways. Furthermore, the synthesis of large clusters of ribosomal subunits were affected throughout neuropathology development in these mice. Our data suggest that large-scale changes in protein synthesis could underlie cellular dysfunction in AD.

neuroscience↗

bioRxiv2020

Serine Phosphorylation Regulates the P-type Potassium pump KdpFABC

KdpFABC is an ATP-dependent K+ pump that ensures bacterial survival in K+-deficient environments. Whereas transcriptional activation of kdpFABC expression is well studied, a mechanism for down regulation when K+ levels are restored has not been described. Here we show that KdpFABC is inhibited when cells return to a K+-rich environment. The mechanism of inhibition involves phosphorylation of Ser162 on KdpB, which can be reversed in vitro by treatment with serine phosphatase. Mutating Ser162 to Alanine produces constitutive activity, whereas the phosphomimetic Ser162Asp mutation inactivates the pump. Analyses of the transport cycle show that serine phosphorylation uncouples the pump and blocks the cycle after formation of the catalytic aspartyl phosphate intermediate (E1[~]P). Molecular dynamics simulations show that serine phosphorylation has allosteric effects that potentially explain the uncoupling. This regulatory mechanism, unique amongst P-type pumps, furthers our understanding of how bacteria control potassium homeostasis to maintain cell volume and osmotic potential.

biophysics↗