Biology subjects

Ward, N.

Publications and source records attributed to Ward, N..

16 recordsLinked to original sources

bioRxiv2026

MicroRNA miR-219 is required for neural border and neural crest development in Xenopus neurulas

Neural crest (NC) multipotent stem cells give rise to many tissues including most of the peripheral nervous system, pigment cells and the craniofacial mesenchyme and skeleton. During gastrulation and early neurulation, cranial NC cells are specified in the ectoderm territory located between the anterior neural plate ectoderm and the future pre-placodal and lateral non-neural ectoderm. At the end of neurulation, NC cells undergo an epithelial-to-mesenchymal transition and migrate to various locations in the developing embryo where they differentiate. While the fine-tuning of NC specification is increasingly being elucidated, many questions remain, including how microRNAs may govern expression of gene programs during these processes. MicroRNAs are short non-coding 20-22 nucleotides-long RNAs which regulate gene expression through post-transcriptional repression. We have identified miR-219 as a candidate regulator of Xenopus NC development. Here, miR-219-dependent molecular pathways were investigated by morpholino knock-down and reveal NC phenotypes. The development of the NC and adjacent ectoderm was evaluated using whole mount in situ hybridization of key markers (pax3, zic1, xhe2, sox10, snai2, sox2), alcian blue cartilage staining, phenotype analysis, RNA sequencing of microdissected dorsal ectoderm and microRNA rescue experiments. While neural induction is mainly unaffected, miR-219 depletion alters gene expression programs associated with neural border development, resulting in loss of NC specification. HighlightsO_LImiR-219 depletion expands the neural border territory and disrupts neural crest specification. C_LIO_LImiR-219 depletion phenotypes are rescued with miRNA mimics. C_LIO_LImiR-219 morphant neural border expansion is rescued by pax3 depletion. C_LIO_LIRNA-seq reveals specific gene program modulation in miR-219 morphant neural crest. C_LIO_LImiR-219 is predicted to directly downregulate the neural gene Hes5.3. C_LI

developmental biology↗

bioRxiv2026

Quinolinic acid phosphoribosyl transferase moonlights as an apoptosis regulator to empower lung cancer progression

Although nicotinamide adenine dinucleotide (NAD) metabolism is fundamental for cancer cell survival, the role of the de novo NAD biosynthetic pathway, particularly in non-small cell lung cancer (NSCLC), remains largely unknown. Here, we describe a non-canonical role for the rate-limiting enzyme in de novo NAD+ biosynthesis, quinolinate phosphoribosyltransferase (QPRT), in NSCLC progression. We show that QPRT is highly expressed in late-stage tumors and required for NSCLC growth; however, its suppression does not change NAD levels or elicit compensatory NAD biosynthetic activity. Instead, QPRT interacts with caspase-3 and suppresses its activation, protecting NSCLC cells from apoptosis. This reveals a moonlighting function for QPRT in apoptosis regulation independent of its enzymatic activity in tryptophan catabolism. Together, these findings, redefine QPRT as a protein with dual functionality and reveal it as a potential therapeutic target in NSCLC, highlighting the importance of non-canonical roles of metabolic enzymes in cancer biology. SignificanceThis study reveals that QPRT supports NSCLC progression by directly inhibiting caspase-3-mediated apoptosis independent of NAD biosynthesis, redefining its role and highlighting non-enzymatic functions of metabolic enzymes as therapeutic targets.

cancer biology↗

bioRxiv2025

MicroRNA miR-196a controls neural crest patterning by repressing immature neural ectoderm programs in Xenopus embryos.

HighlightsmiR-196a promotes Neural Crest development: O_LIRNA sequencing of the developing neural border and neural crest reveals miR-196a-dependent gene programs. C_LIO_LImiR-196a represses early neural plate programs and reduces pluripotency gene expression. C_LIO_LImiR-196a may directly control neural crest gene sox10 in vivo. C_LI Neural crest (NC) cells form a multipotent stem cell population specified during neurulation, which undergo an epithelial-to-mesenchymal transition (EMT) and migrate extensively in the developing embryo, to generate numerous tissues and cell types including the craniofacial skeleton, the peripheral nervous system and pigment cells. The genetic and molecular details of NC specification are governed by a complex, yet still partially understood gene regulatory network (NC-GRN). In particular, the precise function of microRNAs (miRNA) in this network remains poorly characterized. miRNAs are short non-coding 20-22 nucleotides long RNAs, which control gene expression through post-transcriptional repression. Since miRNA-196a is expressed in the developing neural and NC cells of Xenopus laevis embryos, we here investigated miR-196a function in the NC-GRN, by knocking-down its expression using antisense morpholinos. Depletion of miR-196a revealed major NC and craniofacial phenotypes. These defects were preceded by the perturbed expression of key neural, neural border and NC markers such as sox2/3, zic1/3, pax3, sox10 and snail2. Using RNA sequencing of individual neural border and NC explants, we have identified a signature of genes up- and down-regulated by miR-196a and validate these with rescue experiments using a miRNA mimic. Our study identifies miR-196a as a key actor of early patterning in the dorsal ectoderm, balancing the extent of immature neural plate progenitors with NC and placode specification, while also promoting neuron differentiation within the neural plate.

developmental biology↗

bioRxiv2023

Structural reconstruction of individual filaments in Abeta42 fibril populations assembled in vitro reveal rare species that resemble ex vivo amyloid polymorphs from human brains

Structural polymorphism has been demonstrated for both in vitro and ex vivo amyloid fibrils associated with disease. The manner in which different filament structures are assembled from common building blocks remains unclear but the assembly environment is likely to be a key determinant. To address this, three-dimensional reconstruction of individual filament structures was conducted from atomic force microscopy images to map the structural polymorphism landscape of A{beta}42 amyloid fibril populations formed in vitro under most frequently used buffer conditions. The data show sensitivity of A{beta}42 fibril polymorphism to the assembly environment in both the magnitude of heterogeneity and the types of filament species formed. However, some conserved fibril polymorphs were observed across the experimental conditions. Excitingly, by matching individual filament structures to cryo-electron microscopy derived structural data, rare species in these heterogeneous population clouds that show remarkable similarity to A{beta}42 amyloid polymorphs purified from human patient brains were discovered. These results link in vitro experimental approaches with structures formed in vivo, and highlight the polymorph distribution, and the type and magnitude of structural variations within these heterogeneous molecular distributions as important factors in amyloid biology.

biophysics↗

bioRxiv2023

PP1β opposes classic PP1 function, inhibiting spine maturation and promoting LTP

Protein phosphatase 1 (PP1) regulates synaptic plasticity and has been described as a molecular constraint on learning and memory. There are three neuronal isoforms, PP1, PP1{beta}, and PP1{gamma}, but little is known about their individual functions. PP1 and PP1{gamma} are assumed to mediate the effects of PP1 on learning and memory based on their enrichment at dendritic spines and their preferential binding to neurabin and spinophilin, major PP1 synaptic scaffolding proteins. However, it was recently discovered that human de novo PP1{beta} mutations cause intellectual disability, suggesting an important but ill-defined role for PP1{beta}. In this study, we investigated the functions of each PP1 isoform in hippocampal synaptic physiology using conditional CA1-specific knockout mice. In stark contrast to classic PP1 function, we found that PP1{beta} promotes synaptic plasticity as well as spatial memory. These changes in synaptic plasticity and memory are accompanied by changes in GluA1 phosphorylation, GluN2A levels, and dendritic spine density and morphology, including silent synapse number. These functions of PP1{beta} reveal a previously unidentified signaling pathway regulating spine maturation and plasticity, broadening our understanding of the complex role of PP1 in synaptic physiology.

neuroscience↗

bioRxiv2022

Nuclear inhibitor of protein phosphatase 1 (NIPP1) regulates CNS tau phosphorylation and myelination during development

Nuclear inhibitor of protein phosphatase 1 (NIPP1) is a known regulator of gene expression and has been shown to play roles in many physiological or pathological processes such as stem cell proliferation and skin inflammation. While NIPP1 has many regulatory roles in proliferating cells, its function in the central nervous system (CNS) has not been directly investigated. In the present study, we examined NIPP1 CNS function using a conditional knockout (cKO) mouse model, in which the nipp1 gene is excised from neural precursor cells. These mice demonstrate severe developmental impairments that lead to premature lethality within the first few postnatal weeks. To delineate some of the neurological changes occurring in these animals, we first assessed microtubule associated protein tau, a known target of NIPP1 activity. Furthermore, observed tremors prompted exploration of myelin integrity, an integral structure for CNS function, whose disruption is associated with various neurological disorders and neurodegenerative diseases. First, immunoblotting demonstrated increased phospho-tau and altered AKT and PP1 activity in NIPP1 cKO mice, suggesting increased tau phosphorylation likely results from a shift in kinase/phosphatase activity. Second, immunoblots, electron microscopy, and electrophysiology demonstrated a myelin deficit within the brain and optic nerve. Our study suggests that NIPP1 in neural precursors regulates phosphorylation of tau and CNS myelination and may represent a novel therapeutic target for neurodegenerative diseases.

neuroscience↗

bioRxiv2022

NADK upregulation is an essential metabolic adaptation that enables breast cancer metastatic colonization

Metabolic reprogramming and metabolic plasticity allow cancer cells to fine-tune their metabolism to adapt to the ever-changing environments of the metastatic cascade, for which lipid metabolism and oxidative stress are of particular importance. Continuous production of NADPH, a cornerstone of both lipid and redox homeostasis, is essential for proliferation and cell survival suggesting that cancer cells may require larger pools of NADPH to efficiently metastasize. NADPH is recycled through reduction of NADP+ by several enzymatic systems in cells; however, de novo NADP+ is synthesized only through one known enzymatic reaction, catalysed by NAD+ kinase (NADK). Here, we show that NADK is upregulated in metastatic breast cancer cells enabling de novo production of NADP(H) and the expansion of the NADP(H) pools thereby increasing the ability of these cells to adapt to the oxidative challenges of the metastatic cascade and efficiently metastasize. Mechanistically, we found that metastatic signals lead to a histone H3.3 variant-mediated epigenetic regulation of the NADK promoter, resulting in increased NADK levels in cells with metastatic ability. Together, our work presents a previously uncharacterized role for NADK as an important contributor to breast cancer progression and suggests that NADK constitutes an important and much needed therapeutic target for metastatic breast cancers.

cancer biology↗

bioRxiv2022

PP1 inhibitor-2 promotes PP1γ positive regulation of synaptic transmission

Inhibitor-2 (I-2) is a prototypic inhibitor of protein phosphatase-1 (PP1), a major serine-threonine phosphatase that regulates synaptic plasticity and learning and memory. Although I-2 is a potent inhibitor of PP1 in vitro, our previous work has elucidated that, in vivo, I-2 may act as a positive regulator of PP1. Here we show that I-2 and PP1{gamma}, but not PP1, positively regulate synaptic transmission in hippocampal neurons. Moreover, we demonstrated that I-2 enhances PP1{gamma} interaction with its major synaptic scaffold, neurabin, by Forster resonance energy transfer (FRET)/Fluorescence lifetime imaging microscopy (FLIM) studies, while having a limited effect on PP1 autoinhibitory phosphorylation. Furthermore, our study indicates that the effect of I-2 on PP1 activity in vivo is dictated by I-2 threonine-72 phosphorylation. Our work thus demonstrates a molecular mechanism by which I-2 positively regulates PP1 function in synaptic transmission.

neuroscience↗

bioRxiv2019

Inter-hemispheric inhibition in stroke survivors is related to fatigue and cortical excitability

ObjectivePersistent post-stroke fatigue is a major debilitating condition that has been linked to low corticomotor excitability and aberrant attention, both phenomena that are associated with the inter-hemispheric inhibition balance in the brain. In this study, we examined the relationship between inter-hemispheric inhibitory effective connectivity, motor cortex excitability and chronic persistence of post-stroke fatigue.\n\nMethodsWe tested eighteen non-depressed stroke survivors with minimal motoric and cognitive impairments using spectral dynamic causal modelling (spDCM) of resting state magnetic resonance imaging (rs-fMRI) and transcranial magnetic stimulation (TMS) measures of cortical excitability. We also assessed the levels of non-exercise induced, persistent fatigue using Fatigue Severity Scale (FSS) - a self-report questionnaire which has been widely applied and validated across different conditions. To understand neural effective connectivity mechanisms involved in fatigue and corticomotor excitability we examined the balance in inhibitory connectivity between homologue regions in M1, anterior insula, caudate and thalamus of the resting brain.\n\nResultsInter-hemispheric inhibition balance between left and right M1 accounted for 67% of variability in the reported fatigue (R=.82, p<0.001). Inter-hemispheric inhibition balance in M1 also accounted for 54% of variability in the corticomotor excitability characterised by individual resting motor thresholds (R=.74, p<0.001), a measure that has been associated with subjective fatigue reports. Other examined inter-hemispheric connections did not show significant relationships with either fatigue or cortical excitability measures.\n\nConclusionOur findings suggest that the balance in inter-hemispheric effective connectivity between primary motor regions is involved in regulation of corticomotor excitability and could explain subjective post-stroke fatigue.

neuroscience↗

bioRxiv2019

Fatigue, effort perception and central activation failure in chronic stroke survivors: a TMS and fMRI investigation

Fatigue is commonly seen in stroke survivors and the most common manifestation of fatigue is the requirement of high effort for activities of daily life. In this study we set out to identify the neural correlates of perceived effort and central activation failure, a neurophysiological measure correlated with perceived effort. Methods: Twelve chronic stroke survivors participated in this study. Fatigue levels were quantified using the Fatigue Severity Scale -7, perceived effort was quantified using a 1-10 numerical rating scale while performing an isometric biceps hold task, Central Activation Failure was quantified using the modified twitch interpolation technique using Transcranial Magnetic Stimulation and functional Magnetic Resonance Imaging was used to measure blood-oxygen-level dependent signal (BOLD) from the brain while the participant performed a hand grip task. Analysis: Following standard pre-processing procedures for fMRI data using SPM software, co-variance of BOLD signal with perceived effort levels and central activation failure was evaluated. Correlation analysis was performed between measures of fatigue and effort. Results: The main findings of this study were 1) high fatigue was associated with high perceived effort 2) higher perceived effort was associated with greater increase in BOLD fMRI activity in pre-SMA and the ipsilateral inferior frontal gyrus with increasing force 3) greater Central Activation Failure was associated with higher increase in BOLD fMRI activity in bilateral caudate, contralateral superior frontal gyrus and pre-motor cortices with increasing force.

neuroscience↗

bioRxiv2019

Dose-controlled tDCS reduces electric field intensity variability at a cortical target site

BackgroundVariable effects limit the efficacy of transcranial direct current stimulation (tDCS) as a research and therapeutic tool. Conventional application of a fixed-dose of tDCS does not account for inter-individual differences in anatomy (e.g. skull thickness), which varies the amount of current reaching the brain. Individualised dose-control may reduce the variable effects of tDCS by reducing variability in electric field intensities at a cortical target site.\n\nObjectiveTo characterise the variability in electric field intensity at a cortical site (left primary motor cortex; M1) and throughout the brain for conventional fixed-dose tDCS, and individualised dose-controlled tDCS.\n\nMethodsThe intensity and distribution of the electric field during tDCS was estimated using Realistic Volumetric Approach to Simulate Transcranial Electric Stimulation (ROAST) in 50 individual brain scans taken from the Human Connectome Project, for fixed-dose tDCS (1mA & 2mA) and individualised dose-controlled tDCS targeting left M1.\n\nResultsWith a fixed-dose (1mA & 2mA), E-field intensity in left M1 varied by more than 100% across individuals, with substantial variation observed throughout the brain as well. Individualised dose-controlled ensured the same E-field intensity was delivered to left M1 in all individuals. Its variance in other regions of interest (right M1 and area underneath the electrodes) was comparable with fixed- and individualised-dose.\n\nConclusionsIndividualized dose-control can eliminate the variance in electric field intensities at a cortical target site. Assuming that the current delivered to the brain directly determines its physiological and behavioural consequences, this approach may allow for reducing the known variability of tDCS effects.

neuroscience↗

bioRxiv2019

Recombinant Expression of Aldehyde Dehydrogenase 2 (ALDH2) in Escherichia coli Nissle 1917 for Oral Delivery in ALDH2-Deficient Individuals

Turning red after consuming alcohol may seem like a mere social inconvenience. Yet, this flushing response is caused by an accumulation of acetaldehyde, a carcinogenic intermediate of alcohol metabolism. Aldehyde dehydrogenase 2 (ALDH2) deficiency, the result of a point mutation, produces a less efficient ALDH2. The resulting accumulation of acetaldehyde greatly increases the risk of developing esophageal and head and neck cancers. In this study, we produced recombinant ALDH2 in the probiotic E. coli Nissle 1917, which successfully reduces acetaldehyde levels in simulated oral conditions. Packaged in a hard candy, the ALDH2-probiotic would remain in the mouth to specifically target salivary acetaldehyde. Using mathematical modeling, we also determined how much recombinant ALDH2 is needed to reduce elevated acetaldehyde levels.\n\nFinancial DisclosureThis work was funded by Taipei American School. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.\n\nCompeting InterestsThe authors have declared that no competing interests exist.\n\nEthics StatementN/A\n\nData AvailabilityYes - all data are fully available without restriction. Sequences for the plasmids used in this study are available through the Registry of Standard Biological Parts. Links to raw data are included in Supplementary Information.

synthetic biology↗

bioRxiv2019

Damage to the Right Insula Disrupts the Perception of Affective Touch

Specific, peripheral C-tactile afferents contribute to the perception of tactile pleasure, but the brain areas involved in their processing remain debated. We report the first human lesion study on the perception of C-tactile touch (N = 59), revealing that posterior and anterior right insula lesions reduce tactile, contralateral and ipsilateral pleasantness sensitivity, respectively. These findings are consistent with a posterior-to-anterior pattern of integration of interoceptive information in the frontoinsular junction.

neuroscience↗

bioRxiv2017

Sex-related differences in behavioral and amygdalar responses to compound facial threat cues

During face perception, we integrate facial expression and eye gaze to take advantage of their shared signals. For example, fear with averted gaze provides a congruent avoidance cue, signaling both threat presence and its location, whereas fear with direct gaze sends an incongruent cue, leaving threat location ambiguous. It has been proposed that the processing of different combinations of threat cues is mediated by dual processing routes: reflexive processing via magnocellular (M) pathway and reflective processing via parvocellular (P) pathway. Because growing evidence has identified a variety of sex differences in emotional perception, here we also investigated how M and P processing of fear and eye gaze might be modulated by observers sex, focusing on the amygdala, a structure important to threat perception and affective appraisal. We adjusted luminance and color of face stimuli to selectively engage M or P processing and asked observers to identify emotion of the face. Female observers showed more accurate behavioral responses to faces with averted gaze and greater left amygdala reactivity both to fearful and neutral faces. Conversely, males showed greater right amygdala activation only for M-biased averted-gaze fear faces. In addition to functional reactivity differences, females had greater bilateral amygdala volumes, which positively correlated with behavioral accuracy for M-biased fear. Conversely, in males only the right amygdala volume was positively correlated with accuracy for M-biased fear faces. Our findings suggest that M and P processing of facial threat cues is modulated by functional and structural differences in the amygdalae associated with observers sex.

neuroscience↗

bioRxiv2017

Neurodynamics and connectivity during facial fear perception: The role of threat exposure and signal congruity

Fearful faces convey threat cues whose meaning is contextualized by eye gaze: While averted gaze is congruent with facial fear (both signal avoidance), direct gaze is incongruent with it, as direct gaze signals approach. We have previously shown using fMRI that the amygdala is engaged more strongly by fear with averted gaze, which has been found to be processed more efficiently, during brief exposures. However, the amygdala also responds more to fear with direct gaze during longer exposures. Here we examined previously unexplored brain oscillatory responses to characterize the neurodynamics and connectivity during brief ([~]250 ms) and longer ([~]883 ms) exposures of fearful faces with direct or averted eye gaze. We replicated the exposure time by gaze direction interaction in fMRI (N=23), and observed greater early phase locking to averted-gaze fear (congruent threat signal) with MEG (N=60) in a network of face processing regions, with both brief and longer exposures. Phase locking to direct-gaze fear (incongruent threat signal) then increased significantly for brief exposures at [~]350 ms, and at [~]700 ms for longer exposures. Our results characterize the stages of congruent and incongruent facial threat signal processing and show that stimulus exposure strongly affects the onset and duration of these stages.

neuroscience↗

bioRxiv2017

Anxiety Modulates Perception Of Facial Fear In A Pathway-Specific, Lateralized, Manner

Facial expression and eye gaze provide a shared signal about threats. While averted-gaze fear clearly points to the source of threat, direct-gaze fear renders the source of threat ambiguous. Dual processing routes have been proposed to mediate these processes: reflexive processing via magnocellular (M-) pathway and reflective processing via parvocellular (P-) pathway. We investigated how observers trait anxiety modulates Mand P-pathway processing of clear and ambiguous threat cues. We performed fMRI on a large cohort (N=108) widely ranging in trait anxiety while they viewed fearful or neutral faces with averted or directed gaze. We adjusted luminance and color of the stimuli to selectively engage M- or P-pathway processing. We found that higher anxiety facilitated processing of averted-gaze fear projected to M-pathway, but impaired perception of direct-gaze fear projected to P-pathway. Increased right amygdala reactivity was associated with higher anxiety, only for averted-gaze fear presented to M-pathway. Conversely, increased left amygdala reactivity was associated with higher anxiety for P-biased, direct-gaze fear. This lateralization was more pronounced with higher anxiety. Our findings suggest that trait anxiety has differential effects on perception of clear and ambiguous facial threat cues via selective engagement of M and P pathways and lateralization of amygdala reactivity.

neuroscience↗