Biology subjects

Hart, M.

Publications and source records attributed to Hart, M..

14 recordsLinked to original sources

bioRxiv2026

Sea slugs unplugged: Review of subpopulation sampling in phylogeographic studies of nudibranchs and their allies

Nudibranchs and other sea slugs include many cryptic species groups with unknown phenotypic and ecological diversity. How broadly and deeply should researchers sample those cryptic species pairs to capture the genetic variation within each species and potential adaptive differences between species? Fast and inexpensive surveys of genetic diversity that sample a single well-known locus across the geographical range ("phylogeography unplugged") have long been used to identify structured populations and guide choice of sampling localities for subsequent comparative genomic or phenotypic studies of the same species. Results from such studies might also be used to better understand the expected relationships between sampling and population structure in future comparative studies in other species (including many marine gastropods) for which an unplugged phylogeographic survey is not available or impractical. We reviewed analyses of molecular variance that used mitochondrial barcode sequences from marine sea slugs, and we asked whether there are characteristic patterns of subpopulation sampling that are associated with the magnitude and geographical scale of differentiation. We found wide variation in sampling designs: studies with both many and few samples discovered significant population differentiation or broadly similar distribution of haplotypes on both large and small spatial scales, in species from different higher taxonomic groups and oceans. We found two significant associations between sampling variables and population genetic variables, and we suggest using those associations to help guide (or understand the consequences of) sampling design in future studies.

zoology↗

bioRxiv2026

Ex vivo activation unmasks a sex-convergent, exhaustion-associated CD8+ T cell expansion in Parkinsons disease

Parkinsons disease (PD) affects an estimated 6.4 million men and 5.3 million women worldwide, and still lacks a validated peripheral biomarker. Brain tissue is inaccessible in living patients, making peripheral blood an attractive alternative, but existing studies have profiled immune cells almost exclusively as static, resting-state snapshots that cannot reveal how those cells function under challenge. A longitudinal design, following patients over time, or applying a controlled stimulus to reveal functional differences invisible at rest, offers a more sensitive window onto disease-associated dysfunction, and sex, despite differential PD incidence and progression, is rarely treated as a primary variable. Here, using ex vivo PMA/ionomycin stimulation as a controlled functional challenge, we profiled 195k PBMCs from 84 samples of 14 PD patients and 14 controls by single-cell RNA sequencing across an activation time course (0h, 2h, 4h), stratified by sex throughout. Sex explained more transcriptional variance than disease status, and male and female PD patients showed largely divergent responses at rest that converged, by peak activation, on a discrete CD8+ effector memory T cell subpopulation (Tem-CD8). This subpopulation showed an exhaustion-consistent programme, coinciding with a failure to resolve AP-1 induction and a reduction in inferred intercellular communication. The PD peripheral immune phenotype is therefore better characterised as a activation-dependent response than a fixed resting-state signature, identifying Tem-CD8 exhaustion as a disease-associated, sex-convergent candidate for further study.

neuroscience↗

bioRxiv2026

Aging Rhesus Macaque show tissue and sex-specific balance of drifting and coordinated miRNA programs

Macaques research centrality makes it critical to study their molecular aging. We accomplish this for their non-coding transcriptome by sequencing small RNA from 11 organs, with special focus on brain by including 24 brain regions, sampling males and females between ages 3-35 years. Heart, adrenal gland, corpus callosum and caudate putamen showed the most age-deregulated miRNA trajectories. The MIR-154 family, inside the imprinted, rejuvenation-associated Dlk1-Dio3 cluster, was particularly vulnerable. Known age-associated miRNA families LET-7, MIR-29, MIR-17 and MIR-92 were strongly deregulated, with heavy dependence on tissue and sex. MiRNA genomic clusters deregulation was concordant within tissue-sex combinations, implicating upstream regulation rather than random noise. Cross-species comparison with mouse showed ancient miRNAs dominating age-deregulated trajectories. Deregulation direction in tissues-sex was conserved between species at family/cluster levels, but conservation substantially weakened at individual miRNA level. Thus, we mark a decisive step in translating miRNA aging trajectories between two heavily used model organisms. Key FindingsO_LIHeart, adrenal gland, corpus callosum, caudate putamen are hotspots of miRNA age deregulation, with dramatic influence from sex. C_LIO_LINon-brain organs show tissue specific miRNA change, with inconsistent overlap between tissues. C_LIO_LIGenomic clusters of miRNAs were found to be concordant in their age deregulation direction, dependent on tissue and sex, suggesting upstream regulation. C_LIO_LIThe MIR-154 family, housed inside the heavily imprinted Dlk1-Dio3 cluster and processed from the rejuvenation associated MEG3-MIRG host gene is prominently involved in both non-brain organs and brain regions. C_LIO_LIConcentration of age deregulation in evolutionarily ancient miRNAs across species implies regulatory program rather than epigenetic drift, involving MIR-154, LET-7, MIR-29, MIR-17 and MIR-92 families. C_LIO_LIDirection of change conserved between species at the family / genomic cluster level but diminished substantially at individual miRNA level. C_LI

systems biology↗

bioRxiv2025

Tracking GAD-specific T-cell expansions in Type 1 diabetes by intradermal GAD-Alum challenge

Identifying and monitoring autoreactive T cells that drive beta cell destruction remains a major obstacle to developing effective immunotherapies for type 1 diabetes (T1D). These cells are extremely rare in peripheral blood and cannot be accessed directly from the pancreas. We used intradermal injection of GAD-Alum to recruit GAD-specific T cells to accessible sites in the skin and skin-draining lymph nodes (LNs), sampled by skin suction blisters and ultrasound-guided LN aspiration. Peripheral blood samples obtained before GAD injection were restimulated with GAD in vitro to detect reactive CD4+ T cells. Re-expression of selected T cell receptors (TCRs) confirmed antigen specificity. Up to 70% of T cells at the skin injection site were clonally-expanded and 4 of 14 (28%) re-expressed TCRs were GAD-reactive. In draining LNs 1 of 14 (4%) clonally-expanded TCRs was GAD-reactive, representing [~]0.08% of all T-cells. GAD-reactive cells across compartments displayed Th1 and Th17-associated transcription signatures. These results demonstrate the intradermal autoantigen challenge, coupled with scRNAseq, enables direct identification and molecular profiling of autoreactive T cells in vivo. This minimally invasive approach provides a powerful platform for tracking antigen-specific specific T cells to monitor disease activity and evaluate immune interventions in T1D.

immunology↗

bioRxiv2025

Extracellular vesicles and their RNA cargo facilitate bidirectional cross-kingdom communication between human and bacterial cells

While extracellular vesicles (EVs) are established mediators of intra-species signaling, their role as active participants in cross-kingdom communication remains incompletely understood. Here, we reveal that human colon cells and both Gram-positive and Gram-negative gut bacteria engage in species-specific, EV-mediated molecular dialogue, driven in part by RNA cargo. We show that bacterial EVs (BEVs) induce distinct transcriptomic responses in human cells, and that BEV-RNA independently causes similar effects. Conversely, we demonstrate that human EVs and highly abundant miR-192-5p are differentially internalized by bacteria, affecting their physiology. Our findings support a conceptual model in which EVs function as directional messengers that shape host-microbiome interactions. This study introduces a framework for understanding EVs as cross-kingdom regulators and underscores the importance of tailored, context-specific analyses for understanding the scope of EV-mediated interactions in microbiome-host homeostasis and disease. Highlights[1] L. casei, E. faecalis and P. mirabilis produce BEVs that are internalized by Caco-2 cells at different rates. BEVs produced by L. casei have a positive influence on the viability of Caco-2 cells. Incubation of Caco-2 cells with BEVs leads to changes in the gene expression of immune-response-related genes. [2] BEVs carry RNAs and the type of RNA cargo varies significantly between the BEVs from the different bacteria. Comparison of Caco-2 gene deregulation between BEVs and transfection of RNA isolated from BEV highlights component-specific effects. [3] Caco-2 EVs are taken up by E. faecalis and influence their growth. MiRNA-192-5p can be frequently detected in EVs from Caco-2 cells. Synthetic miR-192-5p is internalized by P. mirabilis and the ability to take up human miRNAs by L. casei and E. faecalis can be increased by packaging of the miRNA in artificial liposomes.

molecular biology↗

bioRxiv2024

Evoked resonant neural activity outperforms spectral markers in decoding sleep from the subthalamic nucleus

BackgroundDeep brain stimulation is a treatment for advanced Parkinsons disease and currently tuned to target motor symptoms during daytime. Parkinsons disease is associated with multiple nocturnal symptoms such as akinesia, insomnia and sleep fragmentation which may require adjustments of stimulation during sleep for best treatment outcome. ObjectivesThere is a need for a robust biomarker to guide stimulation titration across sleep stages. This study aimed to investigate whether evoked resonant neural activity (ERNA) is modulated during sleep. MethodsWe recorded local field potentials from the subthalamic nucleus of four Parkinsons patients with externalised electrodes while applying single stimulation pulses to investigate the effect of sleep on ERNA. ResultsWe found that ERNA features change with wakefulness and sleep stages, and are correlated with canonical frequency bands and heart rate. We further evaluated the performance of machine learning models in classifying non-REM sleep versus wakefulness and found that ERNA amplitude outperforms all spectral markers. ConclusionsGiven the heterogeneity of spectral features during sleep, their susceptibility to movement artefacts and superior classification accuracy of models using ERNA features, this study paves the way for ERNA as a marker for automatic stimulation titration during sleep and improved patient care.

neuroscience↗

bioRxiv2023

Th17 cells target the metabolic miR-142-5p-SDHC/SDHD axis promoting invasiveness and progression of cervical cancers

During cervical carcinogenesis, T-helper (Th)-17 cells accumulate in the peripheral blood and tumor tissues of cancer patients. We previously demonstrated that Th17 cells are associated with therapy resistance as well as cervical cancer metastases and relapse, however, the underlying Th17-driven mechanisms supporting cervical cancer progression are not fully understood as yet. In this study, we found that Th17 cells promote migration and invasion of cervical cancer cells in 2D cultures and 3D spheroids. We demonstrated that Th17 cells induced the expression of miR-142-5p in cervical cancer cells supporting their migration and invasiveness. As the responsible mechanism, we identified the subunits C and D of the succinate dehydrogenase (SDH) complex as new targets of miR-142-5p and provided evidence that Th17 cells reduced the expression of SDHC and SDHD that was dependent on miR-142-5p. Functional downstream analysis with inhibitors of miR-142-5p and siRNA knock down of SDHC and SDHD revealed that Th17-induced miR-142-5p-mediated reduced expression of SDHC and SDHD was responsible for enhanced migration and invasion of cervical cancer cells. Consistently, cervical cancer patients exhibited high levels of succinate in their serum associated with lymph node metastases and diminished expression of SDHD in patients' biopsies significantly correlated with increased numbers of Th17 cells, advanced tumor stage and lymph node metastases. Correspondingly, a combination of weak or negative SDHD expression and a ratio of Th17/CD4+ T cells > 43.90 % in situ was associated with reduced recurrence free survival. In summary, we unraveled a novel molecular mechanism by which Th17 cells promote cervical cancer progression and suggest evaluation of Th17 cells as a potential target for immunotherapy in cervical cancer.

cancer biology↗

bioRxiv2023

Structure of the PfRCR complex which bridges the malaria parasite and erythrocyte during invasion

The symptoms of malaria occur during the blood stage of infection, when parasites invade and replicate within human erythrocytes. The five-component PfPCRCR complex, containing PfRH5, PfCyRPA, PfRIPR, PfCSS and PfPTRAMP, is essential for erythrocyte invasion by the deadliest human malaria parasite, Plasmodium falciparum. Invasion can be prevented by antibodies or nanobodies against each of these five conserved proteins, making them the leading blood stage malaria vaccine candidates. However, little is known about the molecular mechanism by which PfPCRCR functions during invasion. Here we present the structure of the PfRCR complex, containing PfRH5, PfCyRPA and PfRIPR, determined by cryogenic-electron microscopy. This reveals that PfRIPR consists of an ordered multi-domain core flexibly linked to an elongated tail. We test the hypothesis that PfRH5 opens to insert into the membrane, but instead show that a rigid, disulphide-locked PfRH5 can mediate efficient erythrocyte invasion. Finally, we show that the elongated tail of PfRIPR, which is the target of growth- neutralising antibodies, binds to the PfCSS-PfPTRAMP complex on the parasite membrane. Therefore, a modular PfRIPR is linked to the merozoite membrane through an elongated tail, while its structured core presents PfCyRPA and PfRH5 to interact with erythrocyte receptors. This provides novel insight into the mechanism of erythrocyte invasion and opens the way to new approaches in rational vaccine design.

microbiology↗

bioRxiv2022

String-Pulling as a Behavioral Assessment of Skilled Forelimb Motor Function in a Middle Cerebral Artery Occlusion Rat Model

Stroke is a leading cause of long-term disability in humans and frequently results in bilateral impairments in fine motor control. Many behavioral tasks used to assess rodent models of stroke evaluate a single limb; however, recent work has demonstrated that bilateral hand-over-hand movements used to pull in a string assess skilled movement of both hands. Devascularization focused on the forelimb portion of sensorimotor cortex has been observed to produce persistent disruptions in the topographical organization of string-pulling behavior. The current study examined changes in string-pulling after a more clinically relevant rodent model of stroke via middle cerebral artery occlusion (MCAO). Detailed movement analyses revealed disruptions in the bilateral organization of string-pulling and fine motor control of both hands. Rats missed the string more often with both hands, and when the string was missed on the impaired side, rats continued to cycle through subcomponents of string-pulling behavior as if the string were grasped in the hand. Rats also failed to make a grasping motion with the impaired hand when the string was missed and instead, demonstrated an open-handed raking-like motion. No differences were found in time to approach or to complete the string-pulling task to obtain a reward, demonstrating the importance of using a detailed functional analysis of movement to detect changes in performance. String-pulling behavior is sensitive at detecting changes in bilateral rhythmical hand control following MCAO providing a foundation for future work to investigate other models of stroke and to evaluate the efficacy of therapeutic interventions that enhance neuroplasticity.

animal behavior and cognition↗

bioRxiv2021

Metabolic reprogramming of cytotoxic T lymphocytes by high glucose enhances pancreatic beta cell apoptosis via TRAIL

Cytotoxic T lymphocytes (CTLs) are involved in development of diabetes. However, the impact of excessive glucose on CTL-mediated antigen-independent killing remains elusive. Here, we report that TNF-related apoptosis inducing ligand (TRAIL) is substantially up- regulated in CTLs in environments with high glucose (HG) both in vitro and in vivo. The PI3K- Akt-NF{kappa}B axis and non-mitochondrial reactive oxygen species are essential in HG-induced TRAIL upregulation in CTLs. TRAILhigh CTLs induce apoptosis of pancreatic beta cell line 1.4E7. Metformin and Vitamin D synergistically reduce HG-enhanced expression of TRAIL in CTLs and coherently protect 1.4E7 cells from TRAIL-mediated apoptosis. Notably, in patients with diabetes, correlation between Vitamin D concentrations in plasma and glucose levels is linked to HG-enhanced TRAIL expression on CTLs. Microarray data reveal that OXCT2, an important enzyme in ketone body catabolism, is a promising target in response to vitamin D. Our work not only reveals a novel mechanism of CTL involvement in progression of diabetes, but also establishes CTLs as a target for combined metformin and vitamin D therapy to protect pancreatic beta cells of diabetic patients.

immunology↗

bioRxiv2020

Multinucleation Associated DNA Damage causes quiescence despite compromised p53

Nuclear atypia is one of the earliest hallmarks of cancer progression. How distinct forms of nuclear atypia differently impact cell fate is not understood at the molecular level. Here, we perform single-cell tracking studies to determine the immediate and long-term impact of multinucleation or misshapen nuclei and reveal a significant difference between multinucleation and micronucleation, a catastrophic nuclear atypia known to promote genomic rearrangements and tumour heterogeneity. Tracking the fate of newborn cells exhibiting various nuclear atypia shows that multinucleation, unlike other forms of nuclear atypia, blocks proliferation in p53-compromised cells. Because compromised p53 is seen in over 50% of cancers, we explored how multinucleation blocks proliferation and promotes quiescence. Multinucleation increases 53BP1-decorated nuclear bodies (DNA damage repair platforms), along with a heterogeneous reduction in transcription and protein accumulation across the multi-nucleated compartments. Importantly, Multinucleation Associated DNA Damage (MADD) associated 53BP1-bodies remain unresolved for days, despite an intact NHEJ machinery that repairs laser-induced DNA damage within minutes. This persistent MADD signalling blocks the onset of DNA replication and is associated with driving proliferative G1 cells into quiescence, revealing a novel replication stress independent cell cycle arrest caused by mitotic lesions. These findings call for segregating protective and prohibitive nuclear atypia to inform therapeutic approaches aimed at limiting tumour heterogeneity.

cell biology↗

bioRxiv2020

Altered substance P signaling underlies perivascular sensory nerve dysfunction in inflammatory bowel disease

ObjectiveInflammatory Bowel Disease (IBD) is associated with cardiovascular disease risk and impaired intestinal blood flow, but the functional role of perivascular nerves that control vasomotor function of mesenteric arteries (MAs) perfusing the intestine is unknown in IBD. Because perivascular sensory nerves and their transmitters calcitonin gene-related peptide (CGRP) and substance P (SP) are important mediators of both vasodilation and inflammatory responses, our objective was to identify IBD-related deficits in perivascular sensory nerve function and vascular neurotransmitter signaling. Approach and ResultsIn MAs from an IL-10-/- mouse model, we found that IBD significantly impairs EFS-mediated sensory vasodilation and sensory inhibition of sympathetic vasoconstriction, despite decreased sympathetic nerve density and vasoconstriction. The MA content and EFS-mediated release of both CGRP and SP are slightly decreased with IBD, but IBD has different effects on each transmitter. CGRP nerve density, receptor expression, hyperpolarization and vasodilation are preserved with IBD. In contrast, SP nerve density and receptor expression are increased, and SP hyperpolarization and vasodilation are impaired with IBD. A critical finding is that blocking neurokinin 1 (SP) receptors restored EFS-mediated sensory vasodilation and enhanced CGRP-mediated vasodilation in MAs from IBD but not Control mice. ConclusionsAn aberrant role for the perivascular sensory neurotransmitter SP and its downstream signaling in MAs underlies vascular dysfunction with IBD. With IBD, SP signaling impedes CGRP-mediated sensory vasodilation, contributing to impaired blood flow. Substance P and NK1 receptors may represent an important target for treating vascular dysfunction in IBD.

physiology↗

bioRxiv2019

Bioresponsive Microspheres for On-demand Delivery of Anti-inflammatory Cytokines for Osteoarthritis

Despite innovations in surgical interventions, treatment of cartilage injury in osteoarthritic joints remains a challenge due to concomitant inflammation. Obstructing a single dominant inflammatory cytokine have shown remarkable clinical benefits in rheumatoid arthritis, and similar strategies are being suggested to target inflammatory pathways in osteoarthritis (OA). Here we describe the utility of gelatin microspheres that are responsive to arthritic flares, resulting in on-demand, and spatiotemporally controlled release of anti-inflammatory cytokines for cartilage preservation and repair. These microspheres had net negative charge potential to sequester cationic anti-inflammatory cytokines, and the magnitude of the negative charge potential increased with increase in crosslinking density. The enzymatic degradation of the microcarriers was concentration dependent. Release of anti-inflammatory cytokines from the loaded microspheres was directly correlated with the degradation of the gelatin matrix. Exposure of the IL-4 and IL-13 loaded microspheres reduced the inflammation of chondrocytes up to 80%. Hence, the delivery of these microspheres in an osteoarthritic joint can attenuate the stimulation of chondrocytes to secrete catabolic factors including proteinases and nitric oxide. The microsphere format also allows for minimally invasive delivery and is less susceptible to mechanically-induced drug release and are conformant to the intra-articular space. Consequently, bioresponsive microspheres are an effective tool for OA prevention and treatment.

bioengineering↗

bioRxiv2018

MARK2/Par1b present at retraction fibres corrects spindle off-centering induced by actin disassembly

Tissue maintenance requires adequate cell proliferation and a directed plane of cell division. Retraction fibres can determine the plane of cell division by directing spindle movements; however, retraction fibre components that direct spindle movements remain unclear. We report MARK2/Par1b kinase as a novel component of actin-rich retraction fibres, important for directed spindle movements. A kinase-dead mutant of MARK2 reveals MARK2s ability to monitor actin status. MARK2s localisation at retraction fibres, but not the rest of the cortical membrane or centrosome, is dependent on its kinase activity, highlighting a specialised spatial regulation of MARK2. By subtly perturbing the actin cytoskeleton, we demonstrate MARK2s role in correcting spindle off-centering, induced by lesions in actin assembly. In addition to this mitotic role, we show MARK2s post-mitotic role in ensuring normal G1-S progression and cell proliferation. We propose that MARK2 provides a molecular framework to integrate cortical signals and cytoskeletal changes in both mitosis and interphase.\n\nShort SummaryCoordination of cell proliferation and division is important for tissue maintenance. We report a regulated localisation for MARK2 in mitosis and interphase. We demonstrate its mitotic role in correcting spindle positioning defects and its interphase role in G1-S transition.

cell biology↗