Biology subjects

George, R.

Publications and source records attributed to George, R..

16 recordsLinked to original sources

bioRxiv2026

Extracellular matrix properties and dynamics are important for butterfly scale nanostructure development

Butterfly wing scales are intricately structured, cuticle-derived, extensions of single scale cells. Their highly ordered structures confer a range of functions, including producing structural color, which depends upon unknown molecular mechanisms controlling the secretion and ordering of an extracellular matrix (ECM). To find the genes required for patterning the ECM we compare scale nanostructure development between structurally colored blue scales and non-iridescent black scales on the forewings of the butterfly Heliconius sara using transmission electron microscopy, RNA-seq and proteomics. We first determined that structural differences between the two scale types are established from about half-way through pupal development and then investigated differences in relevant genes and proteins between scale types from this stage onwards. We show that knockouts of the genes coding for zona pellucida (ZP) domain proteins, miniature and trinity, and the cuticle protein gene, Cpr128 produce distinct effects on scale morphology and structure formation. In particular, some highly unusual scale morphologies are observed in miniature knockout individuals, suggesting a previously undescribed role of ZP domain proteins in structuring the ECM of scale cells and in mediating the mechanochemical interactions needed to produce the complex extracellular structures important for biological function in this system.

developmental biology↗

bioRxiv2026

Lactational transfer of synthetic oxytocin and sex-specific suppression of neurodevelopmental risk gene networks in the rat prefrontal cortex

Autism spectrum disorder and related neurodevelopmental disorders (NDDs) affect males at two-to-four times the rate of females, yet the environmental contributors to this sex-differentiated vulnerability remain poorly understood. Here, using a clinically translatable postpartum rat model, we show that synthetic oxytocin (OT) administered for postpartum hemorrhage (PPH) prophylaxis ( PPH-OT), a universally administered obstetric medication, undergoes lactational transfer, confirmed by stable isotope-labeled OT and LC-MS/MS, without altering maternal behavior or neonatal cortical OT receptor expression. In offspring, PPH-OT altered ultrasonic vocalizations during dyadic interaction and caused a male-specific reduction in social approach, without affecting other behavioral domains. Sex-stratified RNA-sequencing of the medial prefrontal cortex (mPFC) revealed pronounced transcriptional dimorphism: males showed 1,732 differentially expressed genes versus 693 in females, and a sex-by-treatment interaction contrast identified 1,229 formally sex-differentiated genes. Male mPFC downregulated genes were significantly enriched for high-confidence NDD risk genes across three independent databases -- SFARI score-1 (highest confidence autism genes; OR = 4.56, p = 0.015), DBD autism (OR = 10.34, p = 7.3x10-{superscript 1}{superscript 2}), and SysNDD autosomal dominant (OR = 9.78, p = 8.4x10-) -- including core regulators of cortical circuit assembly (Grin2a, Grin2b, Reln, Tbr1, Mef2c, and Tcf4), an enrichment pattern largely restricted to males. Hypothalamic transcriptional changes were pronounced but showed no enrichment for NDD risk genes, establishing mPFC specificity. These findings identify PPH-OT as a candidate environmental modifier of male neurodevelopmental vulnerability and provide a pressing rationale for prospective investigation of neurodevelopmental outcomes in PPH-OT-exposed children.

neuroscience↗

bioRxiv2026

Do drugs with biliary toxicity cause cholangiocarcinoma?

AO_SCPLOWBSTRACTC_SCPLOWMany commonly used therapeutic drugs cause biliary toxicity, but it is unclear if they are directly responsible for the increasing incidence of cholangiocarcinoma (CCA). We tested experimentally and analyzed through a cohort approach whether drugs, such as the commonly used antibiotic Augmentin, which is a poster-child of biliary toxicity, are causally linked to CCA development. Using sophisticated analytical tools in cholangiocytes, including single extracellular vesicle (EV) analysis, we found no evidence that Augmentin increases the cholangiocyte malignancy marker YAP1 or phospho-YAP1. Furthermore, we analyzed the CCA incidence in our healthcare system and determined it to be 0.0932% (Augmentin group) and 0.0799% (amoxicillin control group). Although the Augmentin group showed a numerically higher CCA incidence, the association did not reach statistical significance (RR = 1.1669, 95% CI 0.6200-2.1961; Fishers exact test, P = 0.7493). Similarly, we found no evidence for cholangiocarcinoma development with other commonly used drugs, including chlorpromazine, floxuridine, 5-fluorouracil, flucloxacillin and terbinafine. We conclude that there is no direct causal relationship between clinical Augmentin doses and CCA development.

cancer biology↗

bioRxiv2026

Ex vivo maturation of the malaria parasite egress protease SERA6 aids pathway dissection and inhibitor development.

Release (egress) of malaria parasites from host red blood cells (RBC) is a protease-dependent process involving breakdown of the RBC cytoskeleton by a parasite cysteine protease-like protein called SERA6. In the penultimate step of the egress cascade, SERA6 undergoes autoproteolytic maturation triggered upon cleavage by a serine protease called SUB1 and requiring interactions between SERA6 and fragments of another parasite protein called MSA180. Egress can be blocked by treatment of intraerythrocytic parasites with small molecules that prevent the autocatalytic SERA6 maturation step, suggesting that SERA6 is a druggable target. Here we describe the development of a cell-free in vitro system that recapitulates SERA6 maturation. We use the assay to confirm the strict requirement for MSA180 in SERA6 maturation by SUB1 and to show that these 3 components are sufficient for SERA6 maturation. Using a synthetic peptide substrate based on a predicted autocatalytic cleavage site we demonstrate that the fully mature SERA6 is an active proteolytic enzyme and we validate improved small molecule inhibitors of SERA6. Our lead inhibitory compound efficiently blocks egress of asexual blood stage parasites, confirming SERA6 as a new potential antimalarial drug target.

biochemistry↗

bioRxiv2025

Reduced SK channel control of mesolimbic dopamine neuron firing drives reward seeking adaptations in chronic pain

Patients with chronic neuropathic pain typically experience affective symptoms that drive reduced quality of life and negatively impact pain management. Mesolimbic dopamine is necessary for reward valuation and learning, and the existence of a hypodopaminergic state has been proposed to underlie these affective symptoms of chronic pain. However, direct functional evidence for this hypodopaminergic state is lacking, and the mechanisms underlying its emergence over the acute to chronic pain transition are unknown. Here, we find a selective deficit in the ability of mesolimbic dopamine neurons to sustain burst firing, which is apparent uniquely at chronic timepoints following neuropathic injury. As a result, animals are unable to sustain effortful pursuit of rewards under conditions of high effort or time costs. Convergent biophysical modeling and experimental electrophysiology establish that in a spared nerve injury (SNI) model of chronic neuropathic pain, calcium-activated, small-conductance potassium (SK) channel function is impaired, resulting in lower peak firing and earlier entry into depolarization block of mesolimbic dopamine neurons. Critically, dopamine dependent reward learning, formation of cue-reward associations and locomotor activity remain intact, arguing against the interpretation of a generalized hypodopaminergic state. These results elucidate a circuit-level basis for selective motivational deficits emerging in chronic neuropathic pain.

neuroscience↗

bioRxiv2025

Proteomic characterisation of Japanese quails unique seminal foam

Male Japanese quail (Coturnix japonica) produce a unique proctodeal foam upon ejaculation which is thought to enhance fertilisation success. However, the precise function and proteomic characterisation of this foam remain largely unexplored. Using high throughput LC-MS/MS proteomics analysis, we characterised the proteome of the quail seminal foam for the first time. Our analysis confidently identified 224 proteins in the foam using 32 pooled samples from 96 males. 96.4% of proteins had orthologs in the closely related (diverged 35 million years ago) chicken (Gallus gallus) which generated 40 Gene Ontology terms. Further interrogation revealed proteins involved in sperm motility, maturation and DNA protection, suggesting the foam plays a role in fertilisation success. Proteins linked to immune defence and inflammation modulation were identified, indicating the foam may protect sperm from antigens and reduce female immunogenic responses. This work advances our understanding of the function and evolution of Japanese quail unique seminal foam and directs future experiments to investigate the role of key seminal foam proteins in post-copulatory sexual selection. Significance of the StudySeminal fluid plays an important role in fertilisation success, yet the molecular components of seminal fluid and their function remain poorly understood in most species. This study provides the first comprehensive proteomic characterisation of a unique seminal foam produced by the Japanese quail (Coturnix japonica), revealing its potential mechanistic function in sperm regulation, sperm motility, immune protection, and fertilisation success. By identifying key proteins associated with energy production, membrane fluidity, and sperm maturation, our findings suggest the foam may influence post-ejaculatory sperm function. Additionally, the identification of immunity proteins indicates a role in sperm protection and modulation of female immune responses. This study advances our understanding of avian reproductive biology and opens new avenues for investigating the specific role of seminal foam proteins in fertilisation dynamics and post-copulatory sexual selection.

evolutionary biology↗

bioRxiv2024

TECPR2 is a Rab5 effector that regulates endosomal cargo recycling

Small GTP-binding (G) proteins of the Rabs, Arfs, and Arls (Arf-like) family mediate the recruitment of their effectors to subcellular membrane-bound compartments, which in turn mediates vesicle budding, motility, and tethering. Here, we report that Tectonin-{beta}-propeller repeat containing protein 2 (TECPR2), a protein mutated in a form of hereditary sensory and autonomic neuropathy (HSAN), is an effector of early endosomal Rab protein, Rab5, and interacts with Rab5 via its C-terminal TECPR repeats. The HSAN-associated TECPR2 (R1336W) missense variant was deficient in Rab5-binding and, consequently, in membrane recruitment. TECPR2-depletion led to perinuclear collapse of recycling endosomes and increased overlap of sorting and degradative subdomain markers on early endosomes. Consistent with a possible role in endocytic recycling, we observed impaired recycling and increased lysosomal degradation of 5{beta}1 integrin receptors upon TECPR2 knockdown. TECPR2 regulates the early endosomal localization of the cargo adaptor for {beta}1 integrins, SNX17, and its-associated protein complex WASH, which mediates actin polymerization on early endosomes. Finally, TECPR2 depletion in the zebrafish model resulted in delayed motility and changes in the neuromuscular junction. Our study supports an early endosomal role for TECPR2 in cargo recycling and provides insights into how its loss-of- function results in a neurodegenerative genetic disorder.

cell biology↗

bioRxiv2024

The human ribosome modulates multidomain protein biogenesis by delaying cotranslational domain docking

Proteins with multiple domains are intrinsically prone to misfold, yet fold efficiently during their synthesis on the ribosome. This is especially important in eukaryotes, where multidomain proteins predominate. Here, we sought to understand how multidomain protein folding is modulated by the eukaryotic ribosome. We used cryo-electron microscopy and hydrogen/deuterium exchange-mass spectrometry to characterise the structure and dynamics of partially-synthesised intermediates of a model multidomain protein. We find that nascent subdomains fold progressively during synthesis on the human ribosome, templated by interactions across domain interfaces. The conformational ensemble of the nascent chain is tuned by its unstructured C-terminal segments, which keep interfaces between folded domains in dynamic equilibrium until translation termination. This contrasts with the bacterial ribosome, on which domain interfaces form early and remain stable during synthesis. Delayed domain docking may avoid interdomain misfolding to promote the maturation of multidomain proteins in eukaryotes.

biochemistry↗

bioRxiv2024

Paired transcriptomic analyses of atheromatous and control vessels reveal novel autophagy and immunoregulatory genes in peripheral artery disease

AbstractO_ST_ABSBackgroundC_ST_ABSPeripheral artery disease (PAD), a significant health burden worldwide, affects lower extremities due to atherosclerotic changes in the peripheral vessels. Although mechanisms of PAD have been studied, the molecular milieu of the plaques localized within peripheral arteries in patients are not well understood. Thus, to identify PAD lesion specific gene expression profiles precluding genetic, environmental and dietary biases, we studied the transcriptomic profile of plaque tissues normalized to non-plaque tissues from the same donors. MethodsTranscriptomic analysis of 9 paired samples of PAD patients from south Indian population was performed with institutional ethics approval and written consent. Plaque tissues were histologically confirmed. Expression of a select target gene set was done by qPCR from the same tissues. Bioinformatic and network analyses were performed using various statistical tools. ResultsA total of 296 upregulated, 274 downregulated genes and 186 non-coding RNAs were identified. STAG1, SPCC3, FOXQ1 and E2F3 were key downregulated genes and CD93 was top upregulated gene. Autophagosome assembly, cellular response to UV, cytoskeletal organization, TCR signaling and phosphatase activity were key dysregulated pathways identified in the study. Telomerase regulation and autophagy were identified as novel interacting pathways using network analysis. Plaque tissue was predominantly composed of immune cells and dedifferentiated cell populations indicated by cell specific marker imputed gene expression analysis. ConclusionThe current study identifies novel genes, non-coding RNAs, associated regulatory pathways and cell composition of the plaque tissue in PAD patients. The autophagy and immunoregulatory genes may drive novel mechanisms resulting in atheroma. These novel interacting networks and genes have the potential for PAD specific therapeutic applications.

molecular biology↗

bioRxiv2023

MiR-155 epigenetically counteracts hypoxia for mitochondrial fitness during germinal center positive selection

To increase antibody affinity against pathogens, positively selected GC-B cells initiate cell division in the light zone (LZ) of germinal centres (GCs). Among those, higher-affinity clones migrate to the dark zone (DZ) and vigorously proliferate by relying on oxidative phosphorylation (OXPHOS). However, it remains unknown how positively selected GC-B cells adapt their metabolism for cell division in the glycolysis-dominant, cell cycle arrest-inducing, hypoxic LZ microenvironment. Here, we show that microRNA (miR)-155 mediates metabolic reprogramming during positive selection to protect high-affinity clones. Transcriptome examination and mass spectrometry analysis revealed that miR-155 regulates H3K36me2 levels by directly repressing hypoxia-induced histone lysine demethylase, Kdm2a. This is indispensable for enhancing OXPHOS through optimizing the expression of vital nuclear mitochondrial genes under hypoxia. The miR-155-Kdm2a interaction is crucial to prevent excessive production of reactive oxygen species and apoptosis. Thus, miR-155-mediated epigenetic regulation promotes mitochondrial fitness in high-affinity clones, ensuring their expansion and consequently affinity maturation.

immunology↗

bioRxiv2023

A Connectome of the Male Drosophila Ventral Nerve Cord

Animal behavior is principally expressed through neural control of muscles. Therefore understanding how the brain controls behavior requires mapping neuronal circuits all the way to motor neurons. We have previously established technology to collect large-volume electron microscopy data sets of neural tissue and fully reconstruct the morphology of the neurons and their chemical synaptic connections throughout the volume. Using these tools we generated a dense wiring diagram, or connectome, for a large portion of the Drosophila central brain. However, in most animals, including the fly, the majority of motor neurons are located outside the brain in a neural center closer to the body, i.e. the mammalian spinal cord or insect ventral nerve cord (VNC). In this paper, we extend our effort to map full neural circuits for behavior by generating a connectome of the VNC of a male fly.

neuroscience↗

bioRxiv2022

Mindin is essential for cutaneous fibrogenesis in a new mouse model of systemic sclerosis

Fibrosis is a result of chronically activated fibroblasts leading to the overproduction of extracellular matrix (ECM), causing tissue hardening and loss of organ function. Systemic sclerosis (SSc) is a fibrotic skin disease marked by inflammation, autoimmunity and vasculopathy along with progressive fibrosis of the skin and internal organs. A major bottleneck in understanding the etiology of SSc has been the lack of a holistic animal model that can mimic the human SSc disease. We found that the transcription factor Snail is overexpressed in the epidermis of SSc patients and a transgenic mouse recapitulating this expression pattern is sufficient to induce hallmark clinical features of the human disease. Using this mouse model as a discovery platform, we have uncovered a critical role for the matricellular protein Mindin in fibrogenesis. Mindin is produced by Snail transgenic skin keratinocytes and aids fibrogenesis by inducing inflammatory cytokine and collagen production in resident dermal fibroblasts. Given the dispensability of Mindin in normal tissue physiology, targeting this protein holds promise as an effective therapy for fibrosis.

pathology↗

bioRxiv2022

Whole genome analysis sheds light on the genetic origin of Huns, Avars and conquering Hungarians

Huns, Avars and conquering Hungarians were Migration Period nomadic groups which arrived in three successive waves in the Carpathian Basin between the 5th and 9th centuries. Based on historical data each of these groups are thought to have arrived from Asia, although their exact origin and relation to other ancient and modern populations has been debated. In this study we have sequenced 9 Hun, 143 Avar and 113 Hungarian conquest period samples, and identified three core populations, representing immigrants from each period, with no recent European ancestry. Our results suggest that this "immigrant core" of both Huns and Avars originated in present day Mongolia, and their origin can be traced back to Xiongnus. On the other hand, the "immigrant core" of the conquering Hungarians derived from an earlier admixture of Mansis, early Sarmatians and descendants of late Xiongnus. In addition, we detected shared Hun-related ancestry in numerous Avar and Hungarian conquest period genetic outliers indicating a genetic link between these successive nomadic groups. Aside from the immigrant core groups we identified that the majority of the individuals from each period were local residents, harboring "native European" ancestry.

genetics↗

bioRxiv2020

Mutations in SKI in Shprintzen-Goldberg syndrome lead to attenuated TGF-β responses through SKI stabilization

Shprintzen-Goldberg syndrome (SGS) is a multisystemic connective tissue disorder, with considerable clinical overlap with Marfan and Loeys-Dietz syndromes. These syndromes have commonly been associated with enhanced TGF-{beta} signaling. In SGS patients, heterozygous point mutations have been mapped to the transcriptional corepressor SKI, which is a negative regulator of TGF-{beta} signaling that is rapidly degraded upon ligand stimulation. The molecular consequences of these mutations, however, are not understood. Here we use a combination of structural biology, genome editing and biochemistry to show that SGS mutations in SKI abolish its binding to phosphorylated SMAD2 and SMAD3. This results in stabilization of SKI and consequently attenuation of TGF-{beta} responses, in both knockin cells expressing an SGS mutation, and in fibroblasts from SGS patients. Thus, we reveal that SGS is associated with an attenuation of TGF-{beta}-induced transcriptional responses, and not enhancement, which has important implications for other Marfan-related syndromes.

biochemistry↗

bioRxiv2019

Genomic epidemiology of a complex, multi-species plasmid-borne blaKPC carbapenemase outbreak in Enterobacterales in the UK, 2009-2014

Carbapenem resistance in Enterobacterales is a public health threat. Klebsiella pneumoniae carbapenemase (encoded by alleles of the blaKPC family) is one of the commonest transmissible carbapenem resistance mechanisms worldwide. The dissemination of blaKPC has historically been associated with distinct K. pneumoniae lineages (clonal group 258 [CG258]), a particular plasmid family (pKpQIL), and a composite transposon (Tn4401). In the UK, blaKPC has caused a large-scale, persistent outbreak focused on hospitals in North-West England. This outbreak has evolved to be polyclonal and poly-species, but the genetic mechanisms underpinning this evolution have not been elucidated in detail; this study used short-read whole genome sequencing of 604 blaKPC-positive isolates (Illumina) and long-read assembly (PacBio)/polishing (Illumina) of 21 isolates for characterisation. We observed the dissemination of blaKPC (predominantly blaKPC-2; 573/604 [95%] isolates) across eight species and more than 100 known sequence types. Although there was some variation at the transposon level (mostly Tn4401a, 584/604 (97%) isolates; predominantly with ATTGA-ATTGA target site duplications, 465/604 [77%] isolates), blaKPC spread appears to have been supported by highly fluid, modular exchange of larger genetic segments amongst plasmid populations dominated by IncFIB (580/604 isolates), IncFII (545/604 isolates) and IncR replicons (252/604 isolates). The subset of reconstructed plasmid sequences also highlighted modular exchange amongst non-blaKPC and blaKPC plasmids, and the common presence of multiple replicons within blaKPC plasmid structures (>60%). The substantial genomic plasticity observed has important implications for our understanding of the epidemiology of transmissible carbapenem resistance in Enterobacterales, for the implementation of adequate surveillance approaches, and for control.\n\nIMPORTANCEAntimicrobial resistance is a major threat to the management of infections, and resistance to carbapenems, one of the \"last line\" antibiotics available for managing drug-resistant infections, is a significant problem. This study used large-scale whole genome sequencing over a five-year period in the UK to highlight the complexity of genetic structures facilitating the spread of an important carbapenem resistance gene (blaKPC) amongst a number of bacterial species that cause disease in humans. In contrast to a recent pan-European study from 2012-2013(1), which demonstrated the major role of spread of clonal blaKPC-Klebsiella pneumoniae lineages in continental Europe, our study highlights the substantial plasticity in genetic mechanisms underpinning the dissemination of blaKPC. This genetic flux has important implications for: the surveillance of drug resistance (i.e. making surveillance more difficult); detection of outbreaks and tracking hospital transmission; generalizability of surveillance findings over time and for different regions; and for the implementation and evaluation of control interventions.

genomics↗

bioRxiv2018

MYCN Amplification and ATRX Mutations are Incompatible in Neuroblastoma

Aggressive cancers often have activating mutations in growth-controlling oncogenes and inactivating mutations in tumor-suppressor genes. In neuroblastoma, amplification of the MYCN oncogene and inactivation of the ATRX tumor-suppressor gene correlate with high-risk disease and poor prognosis. Here we show that ATRX mutations and MYCN amplification are mutually exclusive across all ages and stages in neuroblastoma. Using human cell lines and mouse models, we found that elevated MYCN expression and ATRX mutations are incompatible. Elevated MYCN levels promote metabolic reprogramming, mitochondrial dysfunction, reactive-oxygen species generation, and DNA-replicative stress. The combination of replicative stress caused by defects in the ATRX-histone chaperone complex and that induced by MYCN-mediated metabolic reprogramming leads to synthetic lethality. Therefore, ATRX and MYCN represent an unusual example, where inactivation of a tumor-suppressor gene and activation of an oncogene are incompatible. This synthetic lethality may eventually be exploited to improve outcomes for patients with high-risk neuroblastoma.

cancer biology↗