P-Rex1 directly activates RhoG to regulate GPCR-driven Rac signalling and actin polarity in neutrophils

ABSTRACT G-protein-coupled receptors (GPCRs) regulate the organisation of the actin cytoskeleton by activating the Rac subfamily of small GTPases. The guanine-nucleotide-exchange factor (GEF) P-Rex1 is engaged downstream of GPCRs and phosphoinositide 3-kinase (PI3K) in many cell types, and promotes tumorigenic signalling and metastasis in breast cancer and melanoma, respectively. Although P-Rex1-dependent functions have been attributed to its GEF activity towards Rac1, we show that P-Rex1 also acts as a GEF for the Rac-related GTPase RhoG, both in vitro and in GPCR-stimulated primary mouse neutrophils. Furthermore, loss of either P-Rex1 or RhoG caused equivalent reductions in GPCR-driven Rac activation and Rac-dependent NADPH oxidase activity, suggesting they both function upstream of Rac in this system. Loss of RhoG also impaired GPCR-driven recruitment of the Rac GEF DOCK2, and F-actin, to the leading edge of migrating neutrophils. Taken together, our results reveal a new signalling hierarchy in which P-Rex1, acting as a GEF for RhoG, regulates Rac-dependent functions indirectly through RhoG-dependent recruitment of DOCK2. These findings thus have broad implications for our understanding of GPCR signalling to Rho GTPases and the actin cytoskeleton

SCFAs Induce Mouse Neutrophil Chemotaxis through the GPR43 Receptor

Short chain fatty acids (SCFAs) have recently attracted attention as potential mediators of the effects of gut microbiota on intestinal inflammation. Some of these effects have been suggested to occur through the direct actions of SCFAs on the GPR43 receptor in neutrophils, though the precise role of this receptor in neutrophil activation is still unclear. We show that mouse bone marrow derived neutrophils (BMNs) can chemotax effectively through polycarbonate filters towards a source of acetate, propionate or butyrate. Moreover, we show that BMNs move with good speed and directionality towards a source of propionate in an EZ-Taxiscan chamber coated with fibrinogen. These effects of SCFAs were mimicked by low concentrations of the synthetic GPR43 agonist phenylacetamide-1 and were abolished in GPR43−/− BMNs. SCFAs and phenylacetamide-1 also elicited GPR43-dependent activation of PKB, p38 and ERK and these responses were sensitive to pertussis toxin, indicating a role for Gi proteins. Phenylacetamide-1 also elicited rapid and transient activation of Rac1/2 GTPases and phosphorylation of ribosomal protein S6. Genetic and pharmacological intervention identified important roles for PI3Kγ, Rac2, p38 and ERK, but not mTOR, in GPR43-dependent chemotaxis. These results identify GPR43 as a bona fide chemotactic receptor for neutrophils in vitro and start to define important elements in its signal transduction pathways

Measuring the success of programmes of care for people living with dementia: a protocol for consensus building with consumers to develop a set of Core Outcome Measures for Improving Care (COM-IC).

INTRODUCTION: The Core Outcome Measures for Improving Care (COM-IC) project aims to deliver practical recommendations on the selection and implementation of a suite of core outcomes to measure the effectiveness of interventions for dementia care. METHODS AND ANALYSIS: COM-IC embeds a participatory action approach to using the Alignment-Harmonisation-Results framework for measuring dementia care in Australia. Using this framework, suitable core outcome measures will be identified, analysed, implemented and audited. The methods for analysing each stage will be codesigned with stakeholders, through the conduit of a Stakeholder Reference Group including people living with dementia, formal and informal carers, aged care industry representatives, researchers, clinicians and policy actors. The codesigned evaluation methods consider two key factors: feasibility and acceptability. These considerations will be tested during a 6-month feasibility study embedded in aged care industry partner organisations. ETHICS AND DISSEMINATION: COM-IC has received ethical approval from The University of Queensland (HREC 2021/HE001932). Results will be disseminated through networks established over the project, and in accordance with both the publication schedule and requests from the Stakeholder Reference Group. Full access to publications and reports will be made available through UQ eSpace (https://espace.library.uq.edu.au/), an open access repository hosted by The University of Queensland

Proceedings of the Oxygen Homeostasis/Hypoxia Meeting

© 2004 American Association for Cancer ResearchThe first Oxygen Homeostasis/Hypoxia Meeting was held on February 12, 2003, at the Sheraton National Hotel, Washington, D.C. The meeting was hosted by Drs. S. Percy Ivy and Giovanni Melillo of the National Cancer Institute, NIH. The purpose of the meeting was to stimulate collaborations among the participants who are engaged in different areas of hypoxia research and application, Including basic research on hypoxia, and its induction and consequences; the development of drugs targeting hypoxia and factors involved in pathways leading to (or controlled by) hypoxia; and the development and application of hypoxia imaging techniques and reagents.Bennett Kaufman, Orit Scharf, Jeffrey Arbeit, Margaret Ashcroft, J. Martin Brown, Richard K. Bruick, J. Donald Chapman, Sydney M. Evans, Amato J. Giaccia, Adrian L. Harris, Eric Huang, Randall Johnson, William Kaelin, Jr., Cameron J. Koch, Patrick Maxwell, James Mitchell, Len Neckers, Garth Powis, Joseph Rajendran, Gregg L. Semenza, Jonathan Simons, Erik Storkebaum, Michael J. Welch, Murray Whitelaw, Giovanni Melillo and S. Percy Iv