Biology subjects

Pearce, A.

Publications and source records attributed to Pearce, A..

5 recordsLinked to original sources

bioRxiv2025

Reducing Foetal Bovine Serum Culture Conditions does not affect GPCR Signalling

Animal use in research extends beyond the use of animal models to study physiology and disease. Many aspects of in vitro research use reagents derived from animals, most prolifically the use of foetal bovine serum (FBS) in growth media for cellular models. With the aim to reduce animal use, we investigated the effect of reduced FBS culture conditions on cell growth, as well as different stages of G protein-coupled receptor (GPCR) signalling, a wide area of research which might therefore impact many groups. We identified little differences on cell growth or GPCR signalling when reducing culture FBS percentage from 10% to 5%, using assays ranging from receptor activation to downstream transcription factors stimulation. In addition to diminishing animal use, the reduction of FBS use will also have economic and environmental benefits, which we hope will be of benefit to the wider research community.

pharmacology and toxicology↗

bioRxiv2025

Increased RAMP3 expression enhances GLP-1 mediated Glucose Stimulated Insulin Secretion in a Manner Dependent on Ca2+ Mobilisation

The targeting of the Glucagon-like peptide-1 receptor (GLP-1R) for diabetes and obesity is not a novel strategy, with recent therapeutics showing efficacy in weight loss and glycaemic control. However, they are also associated with side effects, including gastrointestinal disruptions and pancreatitis. Developing agonists with different signalling profiles, or that exert some tissue selectivity can circumvent these on-target, unwanted effects. Receptor activity-modifying proteins (RAMPs) offer the potential to do both, through modulation of agonist binding and signalling, as well as surface expression. The GLP-1R was found to interact with RAMP3, with the heterodimer able to bind agonist at the cell surface. RAMP3 expression biased the receptor towards Ca2+ mobilisation, away from the canonical cAMP-driven signalling. When examining G protein coupling, the interaction with RAMP3 reduced activation of the cognate Gs but increased secondary couplings to Gq and Gi. These increased couplings led to an elevation in glucose-stimulated insulin secretion when cells overexpressing RAMP3 were stimulated with GLP-1. A reciprocal effect was observed when looking at reduced expression of endogenous RAMP3, with a loss of sensitivity to GLP-1 in both glucose and insulin tolerance tests in a Ramp3 knockout mouse. The effects of this interaction can then inform selection of models and peptide design when targeting this receptor for therapeutic intervention. Significance StatementG Protein-Coupled Receptors, such as the Glucagon-Like Peptide-1 (GLP-1) Receptor are common drug targets, although not without side effects due to on-target, unwanted signalling outputs. This study identifies an interacting protein which alters its signalling to promote insulin secretion. This may improve the therapeutic potential of GLP-1 mimetics, enhancing effectual signalling over that associated with unwanted effects by directly targeting this receptor complex.

pharmacology and toxicology↗

bioRxiv2024

Exploring Differences in Functional Connectivity in Australian Rules Football Players : A Resting-State fMRI Study on the Default Mode Network

The effects of non-concussive impacts in contact-sports such as in Australian rules football (ARF) are still largely unexplored. These impacts are often but not always lower in intensity, but occur more frequently than actual concussions. Since non-concussive impacts are often asymptomatic, their significance may be underestimated. Acute or subacute measurement of non-concussive injury is challenging as the pathological response and injury is poorly described. There is therefore a need for a greater understanding of the pathological consequences of exposure. Growing evidence indicates that resting-state functional connectivity (rs-fMRI) changes in the Default Mode Network (DMN) may be an important biomarker that is sensitive to characterize these impacts. In this work, we examined functional connectivity changes within the DMN of ARF players to evaluate its potential as an early biomarker for non-concussive impacts. Based on rs-fMRI, we compare the DMN of 47 sub-elite ARF players (mean age 21.5{+/-}2.7 years [SD], males 57%) and 42 age-matched healthy controls (mean age 23.2{+/-}2.3 years [SD], males 48%) using Independent Component Analysis (ICA) and Dual Regression. This approach permits an unbiased decomposition of brain activity into networks with principled handling of statistical error. An 83% increase in DMN connectivity (as measured by the Strictly Standardized Mean Difference on values derived from Dual Regression) was observed in ARF players in the left retrosplenial cingulate cortex compared to healthy controls (FDR-corrected p-value from dual regression = 0.03, 95% CI computed via bootstrapping was 58% to 116%). The AUC for distinguishing ARF players from controls was 0.80 (95% CI; [0.71, 0.89]), equating to a PPV of 78% and a NPV of 74%. These results are preliminary; future work could investigate robustness to different random initializations of ICA and validate the findings on an independent testing set, as well as investigate longitudinal changes in ARF players over the course of a playing season.

neuroscience↗

bioRxiv2023

Differential effects of prolonged aerobic and resistance exercise on cognitive functioning in sedentary young adults

ObjectivesInconsistencies in the literature make it difficult to outline the relationship between exercise and cognition in young adults. Our aim is to better understand the relationship between prolonged aerobic and resistance exercise and cognitive abilities in sedentary young adults, and how this relationship is mediated by changes in cardiovascular fitness. MethodsTwenty-three volunteers were recruited and assigned to two groups to complete one hour of continuous daily workout sessions of aerobic (SPIN) and anaerobic (SCSW) exercises over a 30 day period. Each subject was provided with a Polar-10 wearable to record the heart rate (HR) activity during the workout sessions. The workout sessions were completed during five consecutive days over four consecutive weeks. Each week, HR data were collected from the last workout session. Volunteers also completed a neurocognitive test battery (Cambridge Brain Sciences, CBS) each exercise session, including an additional baseline measure before exercise regime began. ResultsWe found that memory, reasoning and verbal abilities improved throughout the aerobic, but not the resistance exercise program. We found a positive correlation between heart rate index (HRI) and memory and reasoning test scores. We also found a negative correlation between reasoning ability and HRM (heart rate mean), and heart rate skewness (SKW). The results of a regression model to predict memory and reasoning abiltiies revealed that memory was best predicted by HRI and HRM, while the reasoning ability was best predicted by only HRI. ConclusionRegular aerobic exercises improved specific cognitive performance and it was possible to predict the performance by employing the HR parameters HRI and HRM.

neuroscience↗

bioRxiv2022

Cancer-Associated Mutations Enhance The Sensitivity Of The Trupath GαQ/11 System

G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors and are a common drug target. They can be stabilised in different conformational states by ligands to activate multiple transducers and effectors leading to a variety of cellular responses. The potential of agonists to activate select pathways has important implications for drug discovery. Thus, there is a clear need to profile the initial GPCR signal transduction event, activation of G proteins, to enhance understanding of receptor coupling and guide drug design. The BRET-based biosensor suite, TRUPATH, was recently developed to enable quantification of the activation profiles of all non-visual G proteins (excluding Golf and G14) and has since been utilised in numerous studies. However, it fails to detect Gq/11 activation for a number of GPCRs previously reported to display promiscuous secondary coupling to Gq/11. Here we report modifications to the Gq and G11 biosensors in the switch I region that prevent intrinsic GTPase activity (R183C/Q). Except for the PAC1R, substitution with cancer-associated mutations, Cys or Gln, significantly increased sensitivity to allow detection of robust, reliable, and representative Gq/11 responses to Class B1 GPCRs. We also demonstrate the utility of these modified biosensors for promiscuously coupled class A GPCR that have primary Gs-coupling. Thus, we propose that modification to Gq/11 may also be necessary in other biosensor systems to enable detection of Gq/11 activation.

pharmacology and toxicology↗