Biology subjects

Henderson, L.

Publications and source records attributed to Henderson, L..

13 recordsLinked to original sources

bioRxiv2026

Tired and wired: sleep deprivation prevents emotional adaptation to prolonged and ambiguous threat

Sleep problems are strongly linked to anxiety, but the psychological mechanisms underpinning this relationship are poorly understood. In this pre-registered study, we combined virtual reality, psychophysiology and multidimensional experience sampling to test the hypothesis that sleep deprivation disrupts emotional adaptation to sustained or resolving threat, giving rise to a heightened state of anxiety. Following a night of restful sleep or total sleep deprivation, healthy young adults navigated an immersive virtual world that alternated between ambiguously threatening and non-threatening contexts. Despite initial increases in emotional arousal, sleep-rested individuals quickly downregulated affective responses to ambiguous threat, reflecting efficient adaptation to the aversive virtual environment. Sleep-deprived individuals, by contrast, were unable to overturn elevated arousal responses, and exhibited a breakdown of goal-orientated, emotional control. Interestingly, resting heart rate variability, an index of affective regulatory capacity, mitigated arousal responses to ambiguous threat after sleep deprivation. These findings suggest that impaired adaptation to prolonged threat may represent a key mechanistic pathway linking insufficient sleep to anxiety.

neuroscience↗

bioRxiv2025

A novel frameshift mutation in Phosphoinositide 3-kinase regulatory subunit 1 (PIK3R1) causes immunodeficiency and Amyotrophic Lateral Sclerosis (ALS)

Mutations in PIK3R1, a regulatory subunit of Class I PI3K, are implicated in immune disorders and neurological conditions. We identified a novel heterozygous pathogenic frameshift mutation (c.1710dup) in PIK3R1 in a patient with common variable immunodeficiency who developed slowly progressive Amyotrophic Lateral Sclerosis. Induced pluripotent stem cells (iPSCs) and iPSC-derived motor neurons (iMNs) demonstrated that this mutation resulted in PIK3R1 haploinsufficiency, with downstream activation of AKT, disruption of neuronal electrical function and increased apoptosis in iPSC-derived motor neurons. Single-cell RNA sequencing (scRNA-seq) and pathway analysis of differentially expressed genes showed apoptosis pathways were upregulated in neuronal clusters from iMNs harboring the PIK3R1c.1710 dup mutation. Mutated iPSC-derived brain organoids were smaller than matched controls. scRNA-seq of brain organoids showed more active apoptosis in neuronal clusters of patient-derived brain organoids. These findings identify a critical and novel role for PIK3R1 haploinsufficiency in neuronal function and survival.

neuroscience↗

bioRxiv2024

Chromosomal instability increases radiation sensitivity

Continuous chromosome missegregation over successive mitotic divisions, known as chromosomal instability (CIN), is common in cancer. Increasing CIN above a maximally tolerated threshold leads to cell death due to loss of essential chromosomes. Here, we show in two tissue contexts that otherwise isogenic cancer cells with higher levels of CIN are more sensitive to ionizing radiation, which itself induces CIN. CIN also sensitizes HPV-positive and HPV-negative head and neck cancer patient derived xenograft (PDX) tumors to radiation. Moreover, laryngeal cancers with higher CIN prior to treatment show improved response to radiation therapy. In addition, we reveal a novel mechanism of radiosensitization by docetaxel, a microtubule stabilizing drug commonly used in combination with radiation. Docetaxel causes cell death by inducing CIN due to abnormal multipolar spindles rather than causing mitotic arrest, as previously assumed. Docetaxel-induced CIN, rather than mitotic arrest, is responsible for the enhanced radiation sensitivity observed in vitro and in vivo, challenging the mechanistic dogma of the last 40 years. These results implicate CIN as a potential biomarker and inducer of radiation response, which could provide valuable cancer therapeutic opportunities. Statement of SignificanceCancer cells and laryngeal tumors with higher chromosome missegregation rates are more sensitive to radiation therapy, supporting chromosomal instability as a promising biomarker of radiation response.

cancer biology↗

bioRxiv2024

Automated measurement of cardiomyocyte monolayer contraction using the Exeter Multiscope

We apply a novel microscope architecture, the Exeter Multiscope, to the problem of acquiring image data in rapid succession from nine wells of a 96 well plate. We demonstrate that the new microscope can detect contraction in cardiomyocyte monolayers which have been plated into these wells. Each well is sampled using 500 x 500 pixels across a 1.4 x 1.4 mm field of view, acquired in three colours at 3.7 Hz per well. The use of multiple illumination wavelengths provides post-hoc focus selection, further increasing the level of automation. The performance of the Exeter Multiscope is benchmarked against industry standard methods using a commercial microscope with a motorised stage and demonstrates that the Multiscope can acquire data almost 40 times faster. The data from both Multiscope and the commercial systems are processed by a pixel variance algorithm that uses information from the pixel value variability over time to determine the timing and amplitude of tissue contraction. This algorithm is also benchmarked against an existing algorithm that employs an absolute difference measure of tissue contraction.

biophysics↗

bioRxiv2024

Transcriptomic Meta-analysis Identifies Long Non-Coding RNAs Mediating Zika's Oncolytic Impact in Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is an aggressive and lethal form of brain cancer with few effective treatments. In this context, Zika virus has emerged as a promising therapeutic agent due to its ability to selectively infect and kill GBM cells. To elucidate these mechanisms and expand the landscape of oncolytic virotherapy, we pursued a transcriptomic meta-analysis comparing the molecular signatures of Zika infection in GBM and neuroblastoma (NBM). Over-representation analysis of dysregulated coding genes showed significant enrichment of tumor necrosis factor (TNF), NF-{kappa}B, and p53 signaling pathways. A refined list of long non-coding RNAs consistently dysregulated in Zika-infected GBMs was also developed. Functional review of these candidates revealed their potential regulatory role in Zika-mediated oncolysis. We performed validation of the less-researched targets in adult and pediatric GBM cell lines and found significant differential regulation, as predicted. Altogether, our results provide novel insights into the molecular mechanisms underlying the effect of Zika on GBM. We highlight potential therapeutic targets that could be further interrogated to improve the efficacy of tumor cell death and the utility of Zika as an adjuvant virotherapy for GBM and other related cancers.

cancer biology↗

bioRxiv2024

Improving Inverse Folding models at Protein Stability Prediction without additional Training or Data

Deep learning protein sequence models have shown outstanding performance at de novo protein design and variant effect prediction. We substantially improve performance without further training or use of additional experimental data by introducing a second term derived from the models themselves which align outputs for the task of stability prediction. On a task to predict variants which increase protein stability the absolute success probabilities of PO_SCPLOWROTEINC_SCPLOWMPNN and ESMO_SCPLOWIFC_SCPLOW are improved by 11% and 5% respectively. We term these models PO_SCPLOWROTEINC_SCPLOWMPNN-O_SCPLOWDDC_SCPLOWG and ESMO_SCPLOWIFC_SCPLOW-O_SCPLOWDDC_SCPLOWG.

biophysics↗

bioRxiv2023

Molecular model of a bacterial flagellar motor in situ reveals a "parts-list" of protein adaptations to increase torque

One hurdle to understanding how molecular machines work, and how they evolve, is our inability to see their structures in situ. Here we describe a minicell system that enables in situ cryogenic electron microscopy imaging and single particle analysis to investigate the structure of an iconic molecular machine, the bacterial flagellar motor, which spins a helical propeller for propulsion. We determine the structure of the high-torque Campylobacter jejuni motor in situ, including the subnanometre-resolution structure of the periplasmic scaffold, an adaptation essential to high torque. Our structure enables identification of new proteins, and interpretation with molecular models highlights origins of new components, reveals modifications of the conserved motor core, and explain how these structures both template a wider ring of motor proteins, and buttress the motor during swimming reversals. We also acquire insights into universal principles of flagellar torque generation. This approach is broadly applicable to other membrane-residing bacterial molecular machines complexes.

molecular biology↗

bioRxiv2023

A survey of CIN measures across mechanistic models

Chromosomal instability (CIN) is the persistent reshuffling of cancer karyotypes via chromosome mis-segregation during cell division. In cancer, CIN exists at varying levels that have differential effects on tumor progression. However, mis-segregation rates remain challenging to assess in human cancer despite an array of available measures. We evaluated measures of CIN by comparing quantitative methods using specific, inducible phenotypic CIN models of chromosome bridges, pseudobipolar spindles, multipolar spindles, and polar chromosomes. For each, we measured CIN fixed and timelapse fluorescence microscopy, chromosome spreads, 6-centromere FISH, bulk transcriptomics, and single cell DNA sequencing (scDNAseq). As expected, microscopy of tumor cells in live and fixed samples correlated well (R=0.77; p<0.01) and sensitively detect CIN. Cytogenetics approaches include chromosome spreads and 6-centromere FISH, which also correlate well (R=0.77; p<0.01) but had limited sensitivity for lower rates of CIN. Bulk genomic DNA signatures and bulk transcriptomic scores, CIN70 and HET70, did not detect CIN. By contrast, single-cell DNA sequencing (scDNAseq) detects CIN with high sensitivity, and correlates very well with imaging methods (R=0.83; p<0.01). In summary, single-cell methods such as imaging, cytogenetics, and scDNAseq can measure CIN, with the latter being the most comprehensive method accessible to clinical samples. To facilitate comparison of CIN rates between phenotypes and methods, we propose a standardized unit of CIN: Mis-segregations per Diploid Division (MDD). This systematic analysis of common CIN measures highlights the superiority of single-cell methods and provides guidance for measuring CIN in the clinical setting. SignificanceCancer relies on genomic changes to drive evolution. One type of change, Chromosomal INstability (CIN), promotes plasticity and heterogeneity of chromosome sets via ongoing errors in mitosis. The rate of these errors informs patient prognosis, drug response, and risk of metastasis. However, measuring CIN in patient tissues is challenging, hindering the emergence of CIN rate as a prognostic and predictive clinical biomarker. To advance clinical measures of CIN, we quantitatively tested the relative performance of several CIN measures in tandem using four well-defined, inducible CIN models. This survey revealed poor sensitivity in several common CIN assays and highlights the primacy of single-cell approaches. Further, we propose a standard, normalized unit of CIN, permitting comparison across methods and studies.

cancer biology↗

bioRxiv2022

Indigenous Cultural Safety Training for Applied Health, Social Work and Education Professionals: A PRISMA Scoping Review

BackgroundAnti-Indigenous racism is a widespread social problem in health, social work, and education systems in English-speaking Colonized countries such as Canada, with profound negative impacts to the health and education of Indigenous peoples. In 2015, Canadas Truth and Reconciliation Commission recognized the legacy and impact of Colonization and recommended training programs for these professions on cultural competency and curricula, and on the colonial history of Canada. Yet there is little evidence on best practices for such training, highlighting the need to synthesize existing findings on how these training programs are developed, implemented, and evaluated. MethodsThis scoping review explored the academic literature on Indigenous cultural safety and competence training in the health, social work, and education fields. Medline, EMBASE, CINAHL, ERIC and ASSIA were searched for articles published between 1996-2020 in Canada, United States, Australia, and New Zealand. The Joanna Briggs Institutes three-step search strategy was used as was the PRISMA extension for Scoping Reviews. Data was charted and synthesized in three stages. Results134 were included in this review. Data was extracted on four themes: 1) Article Characteristic; 2) Cultural Safety Concepts, Critiques and Rationale; 3) Characteristics of Cultural Safety Training; and 4) Evaluation Details of Cultural Safety Training. Findings suggest that research on cultural safety training programs in health, social work and education has grown significantly. Nursing and medicine professions have received a significant proportion of cultural training programs, compared with general/allied health, social work, and education. Across fields, professionals and students were targeted equally by training programs. Only half of evaluations of cultural safety and related intervention identified methodological limitations. ImplicationsConsidering, comparing, and contrasting literature on cultural safety and related concepts and how they are applied in practice would advance this scholarly work, as would more robust evaluations of cultural safety and similar training interventions to understand their impact at the individual level. Finally, commitment to meaningfully engage Indigenous communities to develop, implement and evaluate such programs is urgently needed.

scientific communication and education↗

bioRxiv2022

ADOPT: intrinsic protein disorder prediction through deep bidirectional transformers

Intrinsically disordered proteins (IDP) are important for a broad range of biological functions and are involved in many diseases. An understanding of intrinsic disorder is key to develop compounds that target IDPs. Experimental characterization of IDPs is hindered by the very fact that they are highly dynamic. Computational methods that predict disorder from the amino acid sequence have been proposed. Here, we present ADOPT, a new predictor of protein disorder. ADOPT is composed of a self-supervised encoder and a supervised disorder predictor. The former is based on a deep bidirectional transformer, which extracts dense residue level representations from Facebooks Evolutionary Scale Modeling (ESM) library. The latter uses a database of NMR chemical shifts, constructed to ensure balanced amounts of disordered and ordered residues, as a training and test dataset for protein disorder. ADOPT predicts whether a protein or a specific region is disordered with better performance than the best existing predictors and faster than most other proposed methods (a few seconds per sequence). We identify the features which are relevant for the prediction performance and show that good performance can already gained with less than 100 features. ADOPT is available as a standalone package at https://github.com/PeptoneLtd/ADOPT.

bioinformatics↗

bioRxiv2021

Do naps benefit novel word learning? Developmental differences and white matter correlates

Behavioural and neuroimaging data suggest that memory representations of newly learned words undergo changes during nocturnal sleep, including improvements in explicit recall and lexical integration (i.e., after sleep, novel words compete with existing words during online word recognition). Some studies have revealed larger sleep-benefits in children relative to adults. However, whether daytime naps play a similar facilitatory role is unclear. We investigated the effect of a daytime nap (relative to wake) on explicit memory (recall/recognition) and lexical integration (lexical competition) of newly learned novel words in young adults and children aged 10-12 years, also exploring white matter correlates of the pre- and post-nap effects of word learning in the child group with diffusion weighted MRI. In both age groups, a nap maintained explicit memory of novel words and wake led to forgetting. However, there was an age group interaction when comparing change in recall over the nap: children showed a slight improvement whereas adults showed a slight decline. There was no evidence of lexical integration at any point. Although children spent proportionally more time in slow-wave sleep (SWS) than adults, neither SWS nor spindle parameters correlated with over-nap changes in word learning. For children, increased fractional anisotropy (FA) in the uncinate fasciculus and arcuate fasciculus were associated with the recognition of novel words immediately after learning, and FA in the right arcuate fasciculus was further associated with changes in recall of novel words over a nap, supporting the importance of these tracts in the word learning and consolidation process. These findings point to a protective role of naps in word learning, and emphasize the need to advance theories of word learning by better understanding both the active and passive roles that sleep plays in supporting vocabulary consolidation over development.

neuroscience↗

bioRxiv2021

Regulation of Plant Phototropic Growth by NPH3/RPT2-like Substrate Phosphorylation and 14-3-3 Binding

Polarity underlies all plant physiology and directional growth responses such as phototropism. Yet, our understanding of how plant tropic responses are established is far from complete. The plasma-membrane associated BTB-containing protein, NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3) is a key determinant of phototropic growth which is regulated by AGC kinases known as the phototropins (phots). However, the mechanism by which phots initiate phototropic signalling via NPH3, and other NPH3/RPT2-like (NRL) members, has remained unresolved. Here we demonstrate that NPH3 is directly phosphorylated by phot1 both in vitro and in vivo. Light-dependent phosphorylation within a conserved consensus sequence (RxS) located at the extreme C-terminus of NPH3 is necessary to promote its functionality for phototropism and petiole positioning in Arabidopsis. Phosphorylation of this region by phot1 also triggers 14-3-3 binding combined with changes in NPH3 phosphorylation and localisation status. Seedlings expressing mutants of NPH3 that are unable to bind or constitutively bind 14-3-3s show compromised functionality that is consistent with a model where signalling outputs arising from a gradient in NPH3 RxS phosphorylation/localisation across the stem are a major contributor to phototropic responsiveness. Our current findings provide further evidence that 14-3-3 proteins are instrumental components regulating auxin-dependent growth and show for the first time that NRL proteins are direct phosphorylation targets for plant AGC kinases. Moreover, the C-terminal phosphorylation site/14-3-3-binding motif of NPH3 is conserved in several members of the NRL family, suggesting a common mechanism of regulation.

plant biology↗

bioRxiv2020

Critical role for cold shock protein YB-1 in cytokinesis

High levels of the cold shock protein Y-box-binding protein-1, YB-1, are tightly correlated with increased cell proliferation and cancer progression. However, the precise mechanism by which YB-1 regulates proliferation is unknown. Here, we found that YB-1 depletion in several cell lines resulted in cytokinesis failure, multinucleation and an increase in G1 transit time. Rescue experiments indicated that YB-1 was required for completion of cytokinesis. Using confocal imaging of cells undergoing cytokinesis both in vitro and in zebrafish embryos, we found that YB-1 was critical for microtubule organization during cytokinesis. Using mass spectrometry we identified multiple novel phosphorylation sites on YB-1. We show that phosphorylation of YB-1 at multiple serine residues was essential for its function during cytokinesis. Using atomistic modelling we show how multiple phosphorylations alter YB-1 conformation, allowing it to interact with protein partners. Our results establish phosphorylated YB-1 as a critical regulator of cytokinesis, defining for the first time precisely how YB-1 regulates cell division. SUMMARYY-box-binding protein-1, YB-1, is essential for cell division, but it is not clear how it functions. Using live imaging and confocal microscopy we show that YB-1 functions only in the last step of division, specifically being required to initiate cytokinesis.

cell biology↗