Biology subjects

Cai, Z.

Publications and source records attributed to Cai, Z..

At least 19 recordsLinked to original sources

bioRxiv2026

Preclinical Evaluation of Itareparib, a brain penetrant PARP1-selective radioligand, in Glioma Rat Model and Nonhuman Primate

Rationale: Poly(ADP-ribose) polymerase-1 (PARP1) is a central mediator of DNA damage response and is upregulated in glioma, supporting it as a molecular imaging biomarker. However, quantitative PET assessment of PARP1 in infiltrative tumors with a preserved blood-brain barrier remains an unmet need. In this study, we evaluated if [18F]Itareparib, a brain-penetrant, non-trapping, PARP1-selective radioligand with reversible kinetics, could improve brain tumor diagnosis and enable target occupancy studies in neurooncology. Methods: [18F]Itareparib was synthesized and evaluated in an orthotopic rat model of BT142 IDH1-mutant gliomas. Dynamic PET scans were performed with or without the administration of the PARP1-selective inhibitor AZD9574. Standardized uptake value ratios (SUVRs) for tumors were calculated using the contralateral region as reference and compared with distribution volume ratios (DVRs) calculated using kinetic modeling. PARP1-specific binding and tracer stability were assessed using autoradiography, immunofluorescence, biodistribution, and radiometabolite analysis. Brain kinetics of [18F]Itareparib were evaluated in a healthy nonhuman primate (NHP) at baseline and blocking conditions. Results: [18F]Itareparib rapidly entered the rat brains and showed 4-fold higher uptake in BT142 tumors than in the contralateral brain. AZD9574 reduced tumor uptake by 77%, supporting the PARP1-specific binding of [18F]Itareparib in the tumors. SUVR(30-60 min) showed the closest agreement with DVR. Autoradiographic tumor-to-reference mean ratio was 7.3, and AZD9574 reduced the tumor-to-reference ratio by 56%. PARP1 immunofluorescence was higher in tumor than the rest of the brain and correlated with autoradiographic results. In rats, the parent fraction of [18F]Itareparib exceeded 99% in brain through 60 min post tracer injection (p.i.) and was approximately 88% in plasma at 60 min p.i. In the NHP, [18F]Itareparib showed rapid brain uptake, and VT decreased by 21+/-6 % after blocking with AZD9574. Conclusion: [18F]Itareparib showed brain penetration, high in vivo metabolic stability, reversible binding kinetics, and PARP1-specific tumor uptake. These findings support further development of [18F]Itareparib for the quantitative PET imaging of PARP1 in brain tumors.

cancer biology↗

bioRxiv2026

Inferring cascade drivers of VEXAS syndrome by a causal machine learning tool CauNagi

VEXAS syndrome is an adult-onset severe autoinflammatory disease caused by somatic mutations in UBA1, yet the cascade mechanisms linking primitive hematopoietic abnormalities to mature myeloid dysfunctions remain largely unknown. Identifying master regulators of a progressive disease, a black-box process, from complex transcriptomic data also remains challenging. To address this challenge, we developed CauNagi, a computational framework for prioritizing cascade candidate regulators (CCRs). CauNagi integrates a causal representation learning module derived from CausCell with an iterative deep learning backbone adapted from UNAGI; in addition, CauNagi extends these two components with a unique downstream module for CCRs analysis designed to characterize regulatory propagation across hierarchical cellular states. Mechanistically, CauNagi iteratively integrates causal disentangled representation learning with (1) disease-stage cell-state trajectory reconstruction and (2) dynamic regulatory analysis. Benchmarking on single-cell transcriptomic datasets showed that CauNagi preserved cell-type structure in idiopathic pulmonary fibrosis (IPF) and enriched known acute myeloid leukemia(AML)-associated genes among its top-ranked global regulators. When applied to VEXAS syndrome, CauNagi readily revealed inflammatory responses, endoplasmic reticulum stress, and myeloid bias, consistent with the disease features. Furthermore, the CCRs analysis module of CauNagi assisted us in identifying 36 causal drivers, with SPI1, NFKB1, STAT3, and FOS prioritized as high-confidence regulatory hubs linking aberrant myeloid differentiation and inflammatory programs. These findings were further supported by an independent single-cell transcriptomic dataset from a murine VEXAS model. Overall, CauNagi provides a computationally efficient and systematic framework for identifying candidate causal regulators. Beyond hematopoietic diseases, CauNagi may also be applicable to other progressive disorders for which multistage single-cell transcriptomic datasets are available. CauNagi is available at https://github.com/steamed-stuffed-bun/CauNagi.

bioinformatics↗

bioRxiv2026

The representation of vocalizations in structured noise in the mouse auditory cortex

Efficient processing of complex acoustic signals within noisy environments is a fundamental challenge for the auditory system. This study investigates the cortical representation of structured noise and vocalizations embedded in it using widefield calcium imaging with the high-speed Calcium indicator jGCaMP8m in the mouse auditory cortex. The spectrotemporal statistics of the structured noise were controllable, including its temporal variance and cross-frequency correlations. We find that structured noise invokes spatially and temporally complex neural responses across the auditory cortex that reflect the spectrotemporal properties of the noise. We identified partially distinct noise response components: noise onset responses showed stronger overlap with primary than secondary areas, while later suppression components did not show a significant primary-secondary bias. Vocalization-evoked responses were significantly attenuated in the presence of noise compared to silent contexts, exhibiting reduced onset magnitude and altered adaptation dynamics. Using decoding we find the neural representation of vocalizations to become more discriminable with longer preceding noise exposure. Furthermore, structured noise cochleograms could be reconstructed from neural population activity, with performance depending on stimulus statistics, tending to be higher in primary than secondary auditory cortex while remaining substantial across both. These findings suggest that the mouse auditory cortex represents acoustic targets in noise through context-dependent and spatially distributed population activity, shaped by both the statistical structure and temporal history of the acoustic background.

neuroscience↗

bioRxiv2026

Glutamine-regulated VCP acetylation creates a proteostasis vulnerability in RB1-deficient tumor

RB1 deficiency defines an aggressive tumor state with limited therapeutic options. Osteosarcoma represents a clinically relevant model of RB1 deficient malignancy, as RB1 alterations are among the most frequent genomic events in this tumor type. However, the non cell cycle vulnerabilities created by RB1 loss remain incompletely understood. We therefore used osteosarcoma to identify therapeutic dependencies associated with RB1 deficiency. Through high-throughput compound screening, we identified a selective vulnerability of RB1-deficient tumor cells to VCP inhibition. NMS-873 and other VCP-targeting compounds preferentially suppressed RB1 deficient cells across two-dimensional cultures, three-dimensional spheroids, patient-derived organoids, and in vivo tumor models. Mechanistically, VCP inhibition exacerbated proteostasis stress and activated endoplasmic reticulum stress responses in RB1-deficient cells. We further found that VCP function was regulated by glutamine-dependent acetylation, with lysine 615 serving as a dominant acetylation site that modulated sensitivity to VCP inhibition. Glutamine restriction phenocopied, whereas glutamine supplementation partially rescued, the effects of NMS-873 on VCP acetylation and tumor cell growth. Clinical and transcriptomic analyses further linked VCP expression and protein-folding stress programs to aggressive disease features. Together, these findings identify glutamine regulated VCP acetylation as a metabolic proteostasis dependency in RB1-deficient tumors and nominate VCP inhibition as a therapeutic strategy for this difficult-to-target tumor state.

cell biology↗

bioRxiv2026

HIPPOCAMPAL TAU RELATED SIGNAL INDEXES HYPEREXCITABILITY AND NREM SLEEP MEMORY DYSFUNCTION IN TEMPORAL LOBE EPILEPSY

Background Sleep and memory disturbances are common in temporal lobe epilepsy (TLE), yet their relationship with tau-targeted neuroimaging measures remains unclear. We investigated whether in-vivo temporal 18F-MK6240 tracer retention relates to seizure burden, non-rapid eye movement (NREM) sleep microstructure, and memory performance in TLE. Methods This cross-sectional study was conducted from 2019 to 2024 at the Montreal Neurological Institute-Hospital. Eligible patients had unilateral TLE diagnosed according to International League Against Epilepsy criteria and underwent overnight electroencephalography (EEG) recordings, research-protocol 3T magnetic resonance imaging, and 18F-MK6240 positron emission tomography. Regional 18F-MK6240 standardized uptake value ratios (SUVRs), using the cerebellum as the reference region, were quantified in the ipsilateral hippocampus (defined a priori as the primary region of interest), as well as in peri-hippocampal and lateral temporal regions. Electroclinical and neuropsychological measures, including seizure burden (high vs low), N2 interictal epileptiform discharge frequency (frequent vs non-frequent), and memory performance (impaired vs intact), were classified according to predefined clinical criteria. N2 spindle rate and N3 slow-wave rate were quantified from overnight EEG recordings. Findings Of 70 eligible patients, 25 were included (eight [32%] females; mean age 35.2 years [SD 12.1]). Higher ipsilateral hippocampal 18F-MK6240 uptake was observed in participants with greater focal seizure burden (median [IQR] 0.70 [0.67-0.78] vs 0.64 [0.58-0.65], rank-biserial correlation=-0.58, 95% CI -0.82 to -0.19; p=0.02), was associated with lower N2 spindle rate (r=-0.42, 95% CI -0.70 to -0.03; p=0.04) and higher N3 slow-wave rate (r=0.47; 95% CI 0.09 to 0.73; p=0.02), and was also higher in participants with impaired than intact memory performance (n=21; mean [SD] 0.80 [0.12] vs 0.68 [0.10], Cohen's d=1.15, 95% CI 0.07 to 2.21; p=0.04). Associations outside the hippocampus were generally less consistent and less precise, with the largest non-hippocampal estimate observed in peri-hippocampal regions. Interpretation Higher hippocampal 18F-MK6240 uptake was associated with greater focal seizure burden, altered NREM sleep microstructure, and impaired memory performance in TLE. These findings suggest that hippocampal 18F-MK6240 uptake may represent a candidate marker of circuit vulnerability associated with NREM sleep-memory dysfunction in TLE, warranting validation in larger longitudinal studies.

neuroscience↗

bioRxiv2026

Repurposing the TIGR-Tas system for programmable transcription activation

Programmable transcription activators are central to functional genomics, gene therapy, and synthetic biology. However, application of the most versatile CRISPR activators (CRISPRa) is hampered by the bulky size and compact CRISPR systems are constrained by the requirement of long protospacer adjacent motifs (PAMs). To address these limitations, we repurposed the TIGR-Tas RNA-guided DNA-targeting system as a versatile platform for gene activation. By systematically optimizing the fusion architecture of a nuclease-inactivated TasR with gene activation domains, we achieved robust, specific, and multiplexable transcriptional activation of endogenous human genes. This TIGR activation (TIGRa) system could be a superior alternative to CRISPRa systems due to its extreme compactness and potentially PAM-independent targeting capability.

genetics↗

bioRxiv2026

Multiplex genome engineering in yeast using the TIGR-Tas system

Tandem Interspaced Guide RNA (TIGR)-TIGR-associated (Tas) systems are a newly discovered family of ultracompact, modular RNA-guided DNA-targeting proteins that function without a protospacer adjacent motif (PAM) requirement. Their utility as genome engineering tools in microbes remains unexplored. Here, we report the first functional implementation of TIGR-Tas in Saccharomyces cerevisiae for genome engineering. We show that TasR from Parcubacteria (ParTasR) can be programmed by user-defined tigRNAs to generate targeted DNA double-strand breaks at yeast endogenous loci. By co-delivering ParTasR with customized tigRNAs and donor templates, we achieved precise gene fragment deletion and targeted codon substitutions at multiple genomic loci. The multiplex genome engineering capability of this TIGR-Tas system was demonstrated through high-efficiency multiplex gene disruption and chromosomal assembly of a lycopene biosynthesis pathway while inactivating an endogenous gene. This work establishes TIGR-Tas as a valuable addition to the yeast genome engineering toolbox, particularly for applications requiring PAM-independent targeting or compact delivery.

synthetic biology↗

bioRxiv2026

The genetic architecture of dementia risk: how Alzheimer's disease vulnerability converges on lipid metabolism and immune cell networks

Although genome-wide association studies (GWAS) have identified numerous dementia risk loci, their cell-type and tissue-specific contexts remain largely unresolved. We introduced HPA GeneSet Explorer, a statistical pipeline designed to systemically map Genome wide association study (GWAS) disease risk genes across the Human Protein Atlas (HPA). This approach generates a multiscale transcriptomic map of genetic risk, spanning systemic organs, brain regions, and cell types. Applying this framework to Alzheimers disease (AD), Lewy body dementia (DLB), and Frontotemporal dementia (FTD) revealed convergent neuronal enrichment in all three diseases. In addition, we identified AD-specific enrichment in immune system and liver associated gene modules, along with DLB-specific enrichment in ciliary modules. By mapping these vulnerabilities in non-demented samples, we provide a blueprint of the baseline vulnerability hotspots that can precede clinical neurodegeneration, offering new targets for disease-specific therapies and biomarker discovery.

neuroscience↗

bioRxiv2026

Dehydration/1,6-addition-based Site-specific Bioconjugation Unveils Norepinephrinylation as a Widespread Post-translational Modification in the Cellular Proteome

Norepinephrine (NE) is a key neurotransmitter and hormone involved in diverse physiological and pathological processes. Beyond its canonical non-covalent signaling through binding adrenergic receptors, NE also induces protein post-translational modifications (PTMs), representing an emerging regulatory mechanism. Two major forms of NE-derived PTMs have been proposed: non-enzymatic norepinephrinylation (NEylation) of cysteine residues mediated by NE quinone and transglutaminase 2 (TG2)-catalyzed NEylation of glutamine residues. However, the cellular abundance, biochemical basis, and pathophysiological roles of NEylation remain poorly understood due to limited detection tools. Here, we report a novel bioconjugation chemistry for selective labeling and enrichment of the endogenous NEylation proteome in cell lines and tissues, which is based on acid-catalyzed dehydration and 1,6-addition to thiol probes. This strategy enables fluorescence imaging and chemical proteomic profiling, revealing NEylation as a widespread PTM that affects enzymatic activities of modified proteins, including protein tyrosine-protein phosphatase non-receptor type 11 (PTPN11). Visual Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=75 SRC="FIGDIR/small/731782v3_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@406ac5org.highwire.dtl.DTLVardef@121d6b9org.highwire.dtl.DTLVardef@98354corg.highwire.dtl.DTLVardef@d312ef_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2026

Biological Aging of the Cardiopulmonary System

Age-related stiffening of large arteries is a predictor of cardiovascular morbidity and mortality, yet how pulmonary vascular stiffening integrates with right ventricular (RV) and lung functional decline--and how best to quantify "biological" cardiopulmonary aging--remains unclear. Here we map cardiopulmonary aging across the adult murine lifespan by integrating RV, proximal pulmonary artery (PA), and lung biomechanics with single-cell transcriptomics. Using ex vivo biaxial testing of the proximal PA, in vivo echocardiography, and lung mechanics, we find that cardiopulmonary aging is phase-dependent: PA circumferential stiffening and reduced distensibility progress largely linearly with age; whereas, RV remodeling and lung mechanical changes exhibit non-linear trajectories. This is consistent with early intrinsic functional decline of cells and organs followed by later, extrinsic load-dependent structural adaptation. To quantify organ-level biological aging, we apply principal component analysis to PA, RV, and lung feature sets to derive physiology-based aging scores that summarize coordinated variance within and across organs. Anchoring differential gene expression in PA single-cell RNA-seq to these continuous biological aging scores rather than chronological age reveals extensive, cell-type-specific remodeling programs (13,636 genes) that are sparse or non-informative when modeled by chronologic age. Biological aging associates across endothelia, smooth muscle cells, fibroblasts, and perivascular macrophages with increased oxidative phosphorylation signatures alongside suppression of adaptive/regulatory pathways, including impaired endothelial mechanotransduction, reduced smooth muscle Wnt signaling, altered extracellular matrix remodeling programs, and erosion of macrophage innate immune and TGF{beta}/NF-{kappa}B signaling nodes. These findings support a model in which pulmonary arterial stiffening is not merely a marker but an active contributor to cardiopulmonary aging via a biomechanical-metabolic-inflammatory uncoupling that diminishes vasoactive and mechano-adaptive reserve and promotes a positive feedback loop. Together, our work establishes physiology-derived biological aging as a powerful framework for interpreting vascular single-cell aging trajectories and identifies mechanistic pathways to target pulmonary vascular stiffening and preserve cardiopulmonary function with age.

physiology↗

bioRxiv2026

The electro-MICA toolbox for integrating electrophysiology within multimodal imaging and connectomics workflows

AO_SCPLOWBSTRACTC_SCPLOWThe integration of electrophysiological recordings with multimodal neuroimaging data holds great promise for advancing our understanding of brain function and neurological disorders. To facilitate this endeavour, we present electro-MICA, an open-access Python toolbox designed to project electrophysiological features from scalp and intracranial electroencephalography (EEG) onto cortical and hippocampal surfaces generated by validated multimodal imaging ecosystems. The toolbox comprises two pipelines: one for intracranial EEG (iEEG) recorded with stereo-EEG depth electrodes, and one for scalp EEG source localization. Both pipelines are grounded in numerical solutions to the electromagnetic equations governing electric activity in the brain, solved using the Boundary Element Method. A key methodological contribution is the use of a current density double layer model for neural generators, which avoids the mathematical singularities introduced by conventional dipole-based models when electrodes are near the cortical surface, a situation that can arise in iEEG. Electrode contacts are additionally modeled with non-zero length, improving physical realism. Scalp EEG source localization is performed using eLORETA on a subject-specific three-layer head model derived from the anatomical input. Validation against empirical gamma-band iEEG data from 32 subjects demonstrates that the distributed generator model outperforms both distance-based and dipole-based alternatives. An illustrative clinical example demonstrates the toolboxs capacity to reveal associations between intracranial spike rates, cortical thickness, and anatomical connectivity in an epilepsy patient. Electro-MICA requires no parameter selection from the user, facilitating straightforward multimodal analyses in both research and clinical settings. The toolbox is available at github.com/MICA-MNI/electromica with extensive online documentation at electromica.readthedocs.io.

neuroscience↗

bioRxiv2026

MetaMAG Explorer: A Database-Augmenting Pipeline for Genome-Resolved Metagenomics and Enhanced Microbial Classification

Accurate taxonomic classification in metagenomic studies remains challenging because reference databases are often static and incomplete, limiting our understanding of microbial diversity, especially in habitats that are not well represented. We introduce MetaMAG Explorer, a complete and modular pipeline designed to fill this gap with its unique database augmentation framework. Together with end-to-end features like read preprocessing, assembly, binning, and annotation, MetaMAG also presents an automated method for finding new metagenome-assembled genomes (MAGs), confirming their uniqueness by dereplication against curated repositories, and dynamically adding them to classification databases that are compatible with Kraken2. Additionally, MetaMAG makes it easier to understand data by automatically creating high-quality figures that are ready for publication, allowing results to be quickly included in scientific papers. Evaluated across human, plant, and rumen datasets, MetaMAG recovered 233 MAGs, including 121 high-quality genomes, of which 48 (20%) were novel. Database augmentation increased Kraken2 classification rates and reassigned millions of previously misclassified reads. Beyond the gain in read classification, the database augmentation revealed ecologically important taxa that are consistently present in all samples but previously undetected. By enabling iterative database growth driven by the novel MAGs, MetaMAG offers a scalable, highly reproducible, and extensible solution for truly genome-resolved metagenomics, advancing both microbial discovery and taxonomic classification accuracy.

bioinformatics↗

bioRxiv2026

Combination of engineered cell type-specific promoters and a high-efficiency AAV capsid restores hearing in adult DFNB1 mice model with demonstrated safety in nonhuman primate

A major challenge in gene therapy for GJB2-related hearing loss (DFNB1)--the most common form of hereditary deafness--is achieving efficient and precise connexin 26 delivery. Herein, we engineered two cell type-specific promoters (GJB2-1 and WFS1-2274) and developed an AAV capsid, AAV-MAS012, with enhanced transduction efficiency in mature cochlear cells. Our AAV-mediated gene therapy systems restored hearing of low-to-mid-frequencies in newborn Gjb2 cKO mice to wild-type levels and maintained for 45 weeks. Additionally, our therapeutic systems restored low-to-mid-frequencies hearing function to wild-type levels in adult Gjb2 cKO mice. A humanized version of the therapy, AAV-MAS012-WFS1-2274-hGJB2, rescued hearing function in two distinct Gjb2-deficient mouse models, and demonstrated a favorable safety profile in nonhuman primates. This study represents the first successful hearing restoration in adult Gjb2-deficient mice. The significant therapeutic efficacy of the humanized gene therapy system shows great potential for clinical translation in DFNB1 patients.

genetics↗

bioRxiv2026

Asymmetric Hydration and Protonation Switching of Dual Aspartates Drive Flagellar Rotation

The bacterial flagellar motor is an intricate nanomachine that transforms chemical energy from ion gradients into mechanical rotation, enabling bacterial movement. While stator unit architectures are conserved across species, the molecular link connecting ion translocation to rotational force generation remains elusive. In this study, we refined the cryo-EM structures of MotAB from Campylobacter jejuni (CjMotAB) and integrated a suite of approaches--including single-structure based pKa predictors and free energy perturbation (FEP) calculations, as well as standard and constant-pH molecular dynamics (CpHMD) simulations of various structural models representing the plugged, unplugged, and plug-removed states with different protonation states of D22--to dissect its rotational mechanism. Based on pKa calculations, the D22 residues in chains F and G of MotB were identified as proton carriers supporting the previous hypotheses. Importantly, we observed asymmetric hydration patterns of the two D22 residues in the MotB dimer, along with their hydrogen bonding interactions with MotA T189, which contribute to functional specialization. Our findings reveal that MotA rotation requires two essential prerequisites: plug removal and alternating D22 protonation switching, coupled with dynamic gauche-trans conformational changes in the sidechain of D22. This work clarifies how protonation dynamics and structural asymmetry synergistically regulate CjMotAB rotation, advancing our understanding of bacterial flagellar motor function and providing a foundational framework for investigating diverse ion-driven biological motors.

biophysics↗

bioRxiv2026

Chemical Proteomic Profiling of the Histaminylation Proteome in Cancer Cells Unveils Uncharted Epigenetic Marks on Core Histones

Histamine is a key signaling molecule in pathophysiology that can exhibit significant regulatory roles in diverse health and disease status. Besides the well-studied noncovalent interactions between histamine and its receptors, protein histaminylation is a recently discovered mechanism of action, through which histamine regulates cellular signaling pathways in a covalent modification manner. Histaminylation is an emerging protein post-translational modification, where an isopeptide bond is formed between the histamine primary amine and {gamma}-carboxyl group of glutamine through a transamidation reaction catalyzed by transglutaminase 2 (TGM2). However, due to the lack of efficient pan-specific antibodies targeting histaminylated glutamine, the histaminylation proteome in cells remains poorly explored. Here, we report the design and development of a novel N{tau}-propargylated histamine (N{tau}-PH) probe as well as its successful application in chemical proteomic profiling of the histaminylation proteome in cancer cells. Notably, new TGM2-catalyzed epigenetic marks on core histones, e.g., H2AX-Q84 and Q104 histaminylation, have been identified from cancer cells and verified. Lastly, the crosstalk between H2AX histaminylation and {gamma}H2AX formation was discovered in this study, suggesting that TGM2-mediated histaminylation plays a critical role in DNA damage responses.

biochemistry↗

bioRxiv2026

Multimodal imaging suggests potential immune-vascular contributions to altered regional brain perfusion and oxygen metabolism in Post-COVID-19 Syndrome

Post-COVID-19 Syndrome (PCS) frequently presents with persistent fatigue, cognitive impairment, and emotional symptoms. Although structural brain changes remain subtle, growing evidence implicates functional and metabolic disruptions in ongoing symptomatology. We used multimodal MRI to investigate cerebral perfusion and oxygen metabolism in PCS and examined their associations with cognitive function and peripheral biomarkers. We enrolled 40 individuals with prior mild SARS-CoV-2 infection, including 20 with persistent fatigue and 20 recovered controls matched for age, sex, BMI, and acute COVID-19 severity. Participants underwent structural MRI, arterial spin labelling (ASL) to quantify regional cerebral blood flow (CBF), and asymmetric spin echo imaging to estimate oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen consumption (CMRO{square}). We assessed cognition using an online battery and measured serum levels of TNF-, IL-6, IL-8, IL-13, IFN-{gamma}, GFAP, and S100{beta}, alongside blood routine tests. We performed ANCOVAs on predefined regions of interest (hippocampus, anterior cingulate cortex [ACC], insula, amygdala, striatum), followed by Bayesian inference and exploratory whole-brain analyses. PCS participants showed increased CMRO{square} in the hippocampus and decreased CMRO{square} in the ACC. Subfield analysis revealed elevated OEF and CMRO{square} across most hippocampal regions, excluding the entorhinal cortex. Whole-brain analyses identified increased perfusion in salience-related regions (insula, ACC, thalamus) and decreased perfusion in posterior cortical and cerebellar areas, in the absence of grey matter volume differences. Higher hippocampal metabolism positively correlated with cognitive performance, suggesting compensatory adaptation to sustain function. In contrast, lower ACC CMRO{square} correlated with depressive symptoms, reduced motivation, and elevated TNF- and GFAP, consistent with neurovascular uncoupling possibly driven by immune-glial activation. These findings reveal distinct physiological disruptions in PCS, with potential implications for stratified, metabolism-focused interventions.

neuroscience↗

bioRxiv2026

Brain dynamics of attentional, default-mode and limbic networks are disrupted at rest in Post-COVID-19 Syndrome

BackgroundPost-COVID-19 Syndrome (PCS) is characterised by persistent fatigue, cognitive impairments, and affective symptoms, yet its underlying neural mechanisms remain poorly understood. While static neuroimaging studies have identified resting-state connectivity abnormalities in PCS, such approaches fail to capture the brains dynamic functional organisation. This represents a missed opportunity to understand how alterations at the dynamic macroscale interactions give rise to the complex and fluctuating symptom profile of PCS. Cognitive and emotional processes rely on the brains capacity to flexibly reconfigure large-scale networks over time; disruptions in the exploration and transition between brain states may therefore play a central role in PCS pathophysiology. MethodsResting-state fMRI data were acquired from 20 individuals with PCS (mean age = 41.8 years, SD = 9.4) and 20 age- and sex-matched healthy controls (mean age = 40.6 years, SD = 8.1) using a multi-echo sequence. Following denoising with multi-echo independent component analysis, we applied Leading Eigenvector Dynamics Analysis (LEiDA) to identify recurrent patterns of whole-brain phase synchrony. The optimal number of dynamic brain states was determined using the Dunn index. For each state, we quantified probability of occurrence, lifetime, and transition probabilities, and mapped spatial topographies onto canonical functional networks. Group differences were assessed using ANCOVAs controlling for age, sex, and handedness. Exploratory associations with clinical symptoms, cognitive performance, and inflammatory markers were examined using both frequentist and Bayesian approaches. ResultsFive recurrent dynamic brain states were identified. Compared with controls, PCS participants showed reduced probability of occurrence and shorter lifetime of a visual/dorsal attention state, alongside increased probability of a limbic/default mode network (DMN) state. PCS was also characterised by reduced transitions between visual/dorsal attention and frontoparietal-DMN states, and increased transitions from somatomotor/visual states toward the limbic-DMN configuration. Exploratory analyses revealed that greater expression of the limbic-DMN state was negatively associated with global cognitive performance (MoCA) and positively associated with serum IL-1{beta} levels. ConclusionsPCS is associated with a reorganisation of intrinsic brain dynamics, marked by a shift from externally oriented attentional states toward limbic-DMN configurations. This imbalance may reflect reduced cognitive flexibility and increased sensitivity to interoceptive or affective signals. The observed links between dynamic brain-state expression, cognitive impairment, and peripheral inflammation support a systems-level mechanism through which immune signalling may influence neural function in PCS. Dynamic functional connectivity offers a sensitive framework for capturing these alterations and may inform future mechanistic models of post-viral dysfunction and therapeutic targeting. HighlightsO_LIPost-COVID-19 Syndrome (PCS) is linked to altered intrinsic brain dynamics at rest. C_LIO_LIPatients show reduced engagement of visual and attentional brain states. C_LIO_LIIncreased recruitment of limbic-DMN states suggests a shift toward more internally, emotionally charged focussed brain activity. C_LIO_LIBrain-state dynamics are putatively associated with global cognition and IL-1{beta}. C_LIO_LIReduced brain-state flexibility may underlie cognitive and emotional symptoms in PCS. C_LI

neuroscience↗

bioRxiv2026

Gliomas preferentially develop within the action-mode network

Gliomas tend to arise in specific brain regions and may integrate into functional circuits, suggesting they could be regulated by brain activity. However, it remains unclear whether glioma growth is related to system-level brain networks. Analyzing neuroimaging data from three datasets including 1,310 patients with cerebral gliomas, we identified and replicated a functionally connected glioma network, which overlaps with the action-mode network (AMN), somatomotor network (SMN), and action-related subcortical regions. Resting-state functional connectivity (RSFC) of the AMN successfully predicted the location of glioma occurrence in two independent datasets with complex tumor distributions. Remarkably, no patient had a glioma entirely outside the AMN, and over 89% of patients exhibited gliomas with at least 50% overlap with the network. Moreover, the spatial overlap between glioma location and the AMN demonstrated significant prognostic value in survival analyses, with higher AMN-tumor overlap associated with poorer overall survival. Notably, the acetylcholine transporter, a key player in glioma pathogenesis that drives transcriptional reprogramming, showed an expression pattern overlapping with the AMN. Meta-analytic annotations further linked the glioma network to processes of action initiation, execution, and feedback. These findings indicate that gliomas preferentially arise in circuits involved in action and highlight the central role of the AMN in glioma pathophysiology and growth.

neuroscience↗