Biology subjects

Bulmer, D.

Publications and source records attributed to Bulmer, D..

7 recordsLinked to original sources

bioRxiv2026

Inhibition of TYK2 attenuates hyper IL-6- and Oncostatin M-mediated Calcium Signalling in Sensory Neurons

Inflammatory bowel disease (IBD) is characterised by chronic pain, a debilitating symptom for which effective treatments are few and far between. IBD pathogenesis includes the prevalence of a variety of pro-inflammatory cytokines, including the Interleukin-6 (IL-6) family members Il-6 and Oncostatin M (OSM). Previous research has shown disruption of OSM signaling can modulate nociceptor sensitization and activation, however the downstream signalling pathway is unknown. When an in silico analysis of murine colonic sensory neuronal populations was undertaken for receptor expression for OSM and other factors necessary for intracellular signaling, we can find diverse expression indicative of functional signaling. We were able to observe that hyper Il-6 (Il-6 bound to the soluble Il-6 receptor) and OSM can elicit activation of a subset of murine sensory neurons by finding an increase in calcium mobilization following superfusion. This could then be attenuated by the pharmacologic inhibition of all janus kinases or interestingly, TYK2 alone. Furthermore, inhibition of transient receptor potential vanilloid 1 or transient receptor potential ankyrin 1 ion channels, which are known to be sensitized by OSM in other sensory neurons also reduced the proportion of OSM-responsive neurons. This further understanding of OSM signaling in sensory neurons creates avenues for more extensive research into the molecular mechanisms occurring as well as the potential to exploit these therapeutically to induce analgesia in a subset of neurons.

neuroscience↗

bioRxiv2025

GPR68, a proton-sensing GPCR, mediates acid-induced visceral nociception

Background & AimsLocalised acidification from immune cell infiltration and heightened glycolysis contributes to colitis pathology by activating acid-sensing receptors such as GPR68, a proton-sensing GPCR expressed on immune and stromal cells. Single-cell RNAseq analysis revealed GPR68 is also expressed in colonic sensory neurons, prompting us to investigate its role in acid-induced colonic nociception. MethodsExpression of GPR68 in colonic nociceptors and tissue from people with colitis was confirmed by in silico analysis of our RNAseq databases. Its contribution to disease activity was assessed using the acute dextran sulphate sodium (DSS) model of colitis. Acid-evoked sensory signalling was evaluated via colonic afferent recordings and Ca{superscript 2} imaging in DRG neurons from wild-type and GPR68-/- mice, supported by pharmacological studies using Ogerin (a GPR68 positive allosteric modulator) and Ogremorphin (a GPR68 antagonist). ResultsRNAseq analysis showed GPR68 is robustly expressed in Trpv1 colonic nociceptors and upregulated in tissue from people with inflammatory bowel disease, consistent with reduced disease activity in DSS-treated GPR68-/- mice. Genetic deletion of GPR68 abolished colonic afferent responses to acid, which were also attenuated by Ogremorphin and enhanced by Ogerin. In Ca{superscript 2}-free buffer, DRG neurons from GPR68-/- mice or those pre-treated with Ogremorphin showed significantly reduced acid-evoked intracellular Ca{superscript 2} responses. By contrast the colonic afferent and DRG Ca2+ response (in Ca2+-containing buffer) to capsaicin was comparable between tissue from wild-type and GPR68-/- mice highlighting the involvement of divergent proton-dependent cellular signalling cascades. ConclusionsThese findings identify GPR68 as a key mediator of acid-induced colonic nociception and highlight its potential as a therapeutic target for the treatment of pain in colitis. SynopsisWe demonstrate that the proton-sensing receptor GPR68 mediates acid-induced signalling in colonic sensory neurons. Genetic and pharmacological modulation confirms GPR68s role in visceral nociception and supports its potential as a therapeutic target for pain management in colitis.

neuroscience↗

bioRxiv2025

IL-17 sensitises sensory neurons and colonic afferents to noxious stimuli in a PI3K dependent manner

Managing visceral pain associated with gastrointestinal (GI) disease remains a significant challenge due to the gut-related side effects and contraindicated use of many commonly used painkillers in people with inflammatory bowel disease (IBD). Consequently, it is crucial to deepen our understanding of the mediators and mechanisms underlying inflammatory pain in people with IBD. To do this, we compared bulk RNA sequencing data from colonic biopsy samples from people with IBD with single-cell RNA sequencing data from colon projecting dorsal root ganglion (DRG) neurons in mice to generate an interactome of putative pro-nociceptive cytokine signalling pathways. This in silico analysis revealed a 10-fold increase in IL17A expression in samples from people with ulcerative colitis (UC) alongside marked co-expression of Il17ra with Trpv1 in colon-projecting DRG neurons in mice, highlighting a likely role for interleukin-17 (IL-17) in colonic nociceptor signalling in people with UC. In support of this, Ca2+ imaging studies demonstrated that IL-17 stimulates DRG sensory neurons co-sensitive to capsaicin with a similar proportion responding in neuron-enriched cultures generated by magnetic-activated cell sorting, thus confirming that IL-17 directly activates DRG neurons. IL-17-evoked Ca2+ signals were attenuated by TRPV1 inhibition, consistent with nociceptor activation, and blocked by inhibition of phosphoinositide 3-kinase (PI3K) activity, consistent with the known role for PI3K as a downstream effector of IL-17 receptor signalling. In keeping with these observations, IL-17 enhanced murine colonic afferent responses to colorectal distension at noxious distension pressures, an effect also blocked by PI3K inhibition. Overall, these findings demonstrate a pro-nociceptive effect of IL-17 in the GI tract, thus highlighting the potential utility of IL-17-targeting therapies to reduce pain in people with UC.

neuroscience↗

bioRxiv2025

Securin and cyclin B1-CDK1, but not SGO2, regulate separase activity during meiosis I in mouse oocytes

During meiosis I in oocytes, anaphase is triggered by deactivation of cyclin B1-CDK1 and activation of separase. Active separase plays an essential role in cleaving cohesin rings that hold homologous chromosomes together. Critically, separase must be inhibited until all chromosomes are aligned and the cell is prepared for anaphase I. Inhibition can be mediated through the binding of separase to either securin or cyclin B1-CDK1. The relative contribution of each inhibitory pathway varies depending on cell type. Recently, shugoshin-2 (SGO2) has also been shown to inhibit separase in mitotic cells. Here, we used a separase biosensor and perturbed the three inhibitory pathways during meiosis I in mouse oocytes. We show that inhibition mediated by either securin or cyclin B1-CDK1, but not SGO2, is independently sufficient to suppress separase activity. However, when both the securin and cyclin B1-CDK1 inhibitory pathways are perturbed together, separase activity begins prematurely, resulting in gross segregation defects. Furthermore, we characterised shugoshin-2 destruction dynamics and conclude that it is not an essential separase inhibitor in mouse oocytes. The existence of multiple separase inhibitory pathways highlights the critical importance of tightly regulated separase activity during this unique and challenging cell division.

cell biology↗

bioRxiv2024

Essential Roles of RodA Peptidoglycan Polymerase and PBP2 Transpeptidase in Expression of Cell Wall-Spanning Supramolecular Organelles and Modulating Salmonella Virulence

The increased spread of multidrug-resistant bacteria no longer sensitive to commonly used antibiotics poses a major threat to human health. The search for potential new drug targets is critical in disease control and prevention. Whilst several components of the cell wall synthesis machinery are already targeted by beta-lactam antibiotics, other elements of this machinery present opportunities for novel drug targets. Landmark studies revealed RodA exhibits peptidoglycan polymerase activity in Bacillus subtilis and Escherichia coli, highlighting RodA as a prime for the next generation of antimicrobial drugs. However, the role of RodA in virulence remains unexplored. Through targeted mutagenesis, virulence gene reporter assays, and phenotypic screening, we demonstrate that the presence of RodA or PBP2, is intrinsically linked to the regulation of virulence gene expression in Salmonella. Specifically, deletion of either of these components causes both disruption in cell morphology and a complete downregulation in major cell invasion-associated virulence factors in vitro, and attenuated virulence in vivo. Significantly, this study highlights the importance of RodA and PBP2 in both the biology and virulence of an important bacterial pathogen, identifying them as promising targets for developing new antibiotics.

microbiology↗

bioRxiv2024

Intestinal barrier function in the naked mole-rat: an emergent model for gastrointestinal insights

The intestinal barrier plays a crucial role in homeostasis, both by facilitating absorption of nutrients and fluids, and providing a tight shield to prevent the invasion by either pathogen or commensal microorganisms. Intestinal barrier malfunction is associated with systemic inflammation, oxidative stress, and decreased insulin sensitivity, which may lead to the dysregulation of other tissues. Therefore, a deeper understanding of physiological aspects related to an enhanced barrier function is of significant scientific and clinical relevance. The naked mole-rat has many unusual biological features, including attenuated colonic neuron sensitivity to acid and bradykinin, and resistance to chemical-induced intestinal damage. However, insight into their intestinal barrier physiology is scarce. Here, we observed notable macroscopic and microscopic differences in intestinal tissue structure between naked mole-rats and mice. Moreover, naked mole-rats showed increased number of larger goblet cells and elevated mucus content. In measuring gut permeability, naked mole-rats showed reduced permeability compared to mice, measured as transepithelial electrical resistance, especially in ileum. Furthermore, intestinal ion secretion induced by serotonin, bradykinin, histamine, and capsaicin was significantly reduced in naked mole-rats compared to mice, despite the expression of receptors for all these agonists. In addition, naked mole-rats exhibited reduced pro-secretory responses to the non-selective adenylate cyclase activator forskolin. Collectively, these findings indicate that naked mole-rats possess a robust and hard-to-penetrate gastrointestinal barrier, that is resistant to environmental and endogenous irritants. Naked mole-rats may therefore provide valuable insights into the physiology of the intestinal barrier and set the stage for the development of innovative and effective therapies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/576063v4_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@1c6c812org.highwire.dtl.DTLVardef@1792503org.highwire.dtl.DTLVardef@6d1c00org.highwire.dtl.DTLVardef@1497fb7_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2020

Uptake of monoaromatic hydrocarbons during biodegradation by FadL channel-mediated lateral diffusion

In modern societies, biodegradation of hydrophobic pollutants generated by industry is important for environmental and human health. In Gram-negative bacteria, biodegradation depends on facilitated diffusion of the pollutant substrates into the cell, mediated by specialised outer membrane (OM) channels. Here we show, via a combined experimental and computational approach, that the uptake of monoaromatic hydrocarbons such as toluene in Pseudomonas putida F1 (PpF1) occurs via lateral diffusion through FadL channels. Contrary to classical diffusion channels via which polar substrates move directly into the periplasmic space, PpF1 TodX and CymD direct their hydrophobic substrates into the OM via a lateral opening in the channel wall, bypassing the polar barrier formed by the lipopolysaccharide leaflet on the cell surface. Our study suggests that lateral diffusion of hydrophobic molecules is the modus operandi of all FadL channels, with potential implications for diverse areas such as biodegradation, quorum sensing and gut biology.

microbiology↗