Dataset Information

The Rac-GEF Tiam1 controls integrin-dependent neutrophil responses

ABSTRACT: Rac GTPases are required for neutrophil adhesion and migration, and for the neutrophil effector responses that kill pathogens. These Rac-dependent functions are impaired when neutrophils lack the activators of Rac, Rac-GEFs from the Prex, Vav and Dock families. In this study, we demonstrate that Tiam1 is also expressed in neutrophils, governing focal complexes, actin cytoskeletal dynamics, polarisation and migration, in a manner depending on the integrin ligand to which the cells adhere. Tiam1 is dispensable for the generation of reactive oxygen species but mediates degranulation and NETs release in adherent neutrophils, as well as the killing of bacteria. In vivo, Tiam1 is required for neutrophil recruitment during aseptic peritonitis and for the clearance of Streptococcus pneumoniae during pulmonary infection. However, Tiam1 functions differently to other Rac-GEFs. Instead of promoting neutrophil adhesion to ICAM1 and stimulating β2 integrin activity as could be expected, Tiam1 restricts these processes. In accordance with these paradoxical inhibitory roles, Tiam1 limits the fMLP-stimulated activation of Rac1 and Rac2 in adherent neutrophils, rather than activating Rac as expected. Tiam1 promotes the expression of several regulators of small GTPases and cytoskeletal dynamics, including αPix, Psd4, Rasa3 and Tiam2. It also controls the association of Rasa3, and potentially αPix, Git2, Psd4 and 14‐3‐3ζ/δ, with Rac. We propose these latter roles of Tiam1 underlie its effects on Rac and β2 integrin activity and on cell responses. Hence, Tiam1 is a novel regulator of Rac-dependent neutrophil responses that functions differently to other known neutrophil Rac-GEFs.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Primary Cell, Neutrophil

SUBMITTER: David Oxley

LAB HEAD: david oxley

PROVIDER: PXD046791 | Pride | 2024-01-26

REPOSITORIES: Pride

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Publications

The Rac-GEF Tiam1 controls integrin-dependent neutrophil responses.

Hornigold Kirsti K Baker Martin J MJ Machin Polly A PA Chetwynd Stephen A SA Johnsson Anna-Karin AK Pantarelli Chiara C Islam Priota P Stammers Melanie M Crossland Laraine L Oxley David D Okkenhaug Hanneke H Walker Simon S Walker Rachael R Segonds-Pichon Anne A Fukui Yoshinori Y Malliri Angeliki A Welch Heidi C E HCE

Frontiers in immunology 20231121

Rac GTPases are required for neutrophil adhesion and migration, and for the neutrophil effector responses that kill pathogens. These Rac-dependent functions are impaired when neutrophils lack the activators of Rac, Rac-GEFs from the Prex, Vav, and Dock families. In this study, we demonstrate that Tiam1 is also expressed in neutrophils, governing focal complexes, actin cytoskeletal dynamics, polarisation, and migration, in a manner depending on the integrin ligand to which the cells adhere. Tiam1 ...[more]

PMID: 38077328

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Project description:Preschool children with recurrent wheezing are heterogeneous, with differing responses to respiratory viral infections. Although neutrophils are crucial for host defense, their function has not been studied in this population. We performed functional immunophenotyping on isolated blood neutrophils from 52 preschool children with recurrent wheezing (aeroallergen sensitization, n=16; no sensitization, n=36). Blood neutrophils were purified and cultured overnight with polyinosinic:polycytidylic acid (poly(I:C)) as a viral analog stimulus. Neutrophils underwent next-generation sequencing with Reactome pathway analysis and were analyzed for cytokine secretion, apoptosis, myeloperoxidase and extracellular DNA release. CD14+ monocytes were also exposed to neutrophil culture supernatant and analyzed for markers of M1 and M2 activation. 495 genes, related largely to the innate immune system and neutrophil degranulation, were differently expressed in children with versus without aeroallergen sensitization. Functional experiments identified more neutrophil degranulation and extracellular trap formation (i.e., more myeloperoxidase and extracellular DNA) and less neutrophil pro-inflammatory cytokine secretion in children with aeroallergen sensitization. Neutrophils also shifted CD14+ monocytes to a more anti-inflammatory (i.e., M2) phenotype in sensitized children and a more pro-inflammatory (i.e., M1) phenotype in non-sensitized children. Although both groups experienced viral exacerbations, annualized exacerbation rates prompting unscheduled healthcare were also higher in children without aeroallergen sensitization after enrollment. Systemic neutrophil responses to viral infection differ by allergic phenotype and may be less effective in preschool children without allergic inflammation. Further studies of neutrophil function are needed in this population, which often has less favorable therapeutic responses to inhaled corticosteroids and other therapies directed at T2-high inflammation.

Dataset Information

The Rac-GEF Tiam1 controls integrin-dependent neutrophil responses

Publications

The Rac-GEF Tiam1 controls integrin-dependent neutrophil responses.

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