Biology subjects

Bewick, G.

Publications and source records attributed to Bewick, G..

4 recordsLinked to original sources

bioRxiv2025

Vitamin D receptor is necessary for metabolic health after sleeve gastrectomy

BackgroundThe vitamin D receptor (VDR) regulates insulin sensitivity. Metabolic bariatric surgery (MBS) remains the most effective treatment for obesity and T2D. However, whether its metabolic effects are VDR-dependent is unknown. Here, we assessed VDR role in the metabolic response to sleeve gastrectomy (SG). MethodsWhole body VDR knockout (KO) and wild type (WT) C57BL/6J mice with diet-induced obesity (DIO) were assigned to either SG or sham procedure. Postoperatively, animals underwent glucose and insulin tolerance tests. On sacrifice, serum, white adipose tissue (WAT), liver and colonic contents were collected for further biochemical, histological and bile acid analysis. Separately, human VDR gene expression was assessed in subcutaneous adipose tissue (SAT) biopsies collected from patients with/without MBS history. ResultsKO SG mice exhibited delayed glucose utilization after an oral challenge and progressive loss of insulin sensitivity, despite the same magnitude of surgery-induced weight change between the two genotypes. WAT in KO SG mice had lower mass, smaller adipocytes and increased inflammation. SG had a differential effect on colonic levels of the glucoregulatory cholic acid 7-sulfate (CA7S): increasing CA7S concentration in the WT mice but decreasing it in the KO mice. Finally, patients with MBS history had higher VDR expression in SAT as compared to those without MBS history. ConclusionVDR is necessary for metabolic health after SG in DIO mice due to its role in WAT function, insulin sensitivity and inflammatory response after surgery. Increased expression of VDR in patients post-MBS suggests that it may also contribute to metabolic responses in humans. HighlightsO_LIVDR KO results in delayed glucose utilization following SG in DIO mice C_LIO_LIVDR KO results in progressive loss of improved insulin sensitivity after SG C_LIO_LIVDR KO results in white adipose tissue inflammation and remodeling after SG C_LIO_LIVDR expression increases in human subcutaneous adipose tissue after bariatric surgery C_LI

physiology↗

bioRxiv2024

Measurement of Real Time Serotonin Dynamics from Human Derived Gut Organoids

The importance of the gut in regulating the brain-body-immune axis is becoming increasingly evident. Interestingly, the brain and gut share many common signalling molecules, with serotonin being one of the most notable. In fact, the gut is the primary source of serotonin in the body. However, studying serotonin dynamics in a human-specific context remains a challenge. Human stem cell-derived models provide a promising avenue for studying signal transmission in well-controlled, in vitro environments. In this study, we report the first fast-scan cyclic voltammetry (FSCV) measurements of serotonin signalling in a newly developed enterochromaffin cell (ECC)-enriched gut organoid model. First, we characterize the stem cell-derived gut organoids and confirmed they are enriched with ECCs - the key cell type responsible for producing and releasing serotonin in the gut. We then optimize an in vitro buffer that maintains cell viability while supporting FSCV measurements. Using this system, we detect spontaneous release events, which increase in frequency and amplitude following stimulation with forskolin (FSK) and 3-isobutyl-1-methylxanthine (IBMX). Finally, we confirm the identity of the signal as serotonin by using a selective serotonin reuptake inhibitor (SSRI), which significantly delayed the reuptake profile. Our study introduces the first real time measurement of serotonin signalling in a human-derived gut model. We believe this system will be essential for future research on serotonins role in the gut and for potential novel drug target identification.

bioengineering↗

bioRxiv2022

Aryl hydrocarbon receptor utilises cellular zinc signals to maintain the gut epithelial barrier

Both zinc and plant-derived ligands of the aryl hydrocarbon receptor (AHR) are dietary components which regulate intestinal epithelial barrier function and protect against Inflammatory Bowel Disease (IBD)1,2. Here, we explore whether zinc and AHR pathway are linked using a mouse IBD model with follow-on studies on human and mouse ileum organoids. Our data demonstrate that AHR regulates cellular zinc uptake, and that zinc is an integral part of AHR signalling processes. We show that dietary supplementation in mice with the plant-derived AHR ligand precursor, indole-3-carbinol (I3C), offers a high level of protection against dextran sulfate sodium induced IBD while protection fails in mice with AHR deleted in the intestinal epithelium. AHR agonist treatment is also ineffective in mice with a nutritional zinc deficiency. Experiments in the human Caco-2 cell line and ileum organoids showed that AHR activation increases total cellular zinc and cytosolic free Zn2+ concentrations through transcriptional upregulation of several SLC39 zinc importers. As a consequence, genes for tight junction (TJ) proteins were upregulated in a zinc-dependent manner involving zinc inhibition of signalling to NF-{kappa}B and attenuated degradation of TJ proteins through zinc inhibition of calpain activity. Thus, our data indicate that AHR activation by plant-derived dietary ligands improves gut barrier function via zinc-dependent cellular pathways, suggesting that combined dietary supplementation with AHR ligands and zinc might be effective in preventing and treating inflammatory gut disorders.

cell biology↗

bioRxiv2022

Molecular characterization of the intact muscle spindle using a multi-omics approach

The proprioceptive system is essential for the control of coordinated movement, posture and skeletal integrity. The sense of proprioception is produced in the brain using peripheral sensory input from receptors such as the muscle spindle, which detects changes in the length of skeletal muscles. Despite its importance, the molecular composition of the muscle spindle is largely unknown. In this study, we generated comprehensive transcriptomic and proteomic datasets of the entire muscle spindle. We then associated differentially expressed genes with the various tissues composing the spindle using bioinformatic analysis. Immunostaining verified these predictions, thus establishing new markers for the different spindle tissues. Utilizing these markers, we identified the differentiation stages the spindle capsule cells undergo during development. Together, these findings provide comprehensive molecular characterization of the intact spindle as well as new tools to study its development and function in health and disease.

developmental biology↗