2020 journal article

The FcεRIβ homologue, MS4A4A, promotes FcεRI signal transduction and store-operated Ca2+ entry in human mast cells

Cellular Signalling, 71, 109617.

By: G. Arthur n, L. Ehrhardt-Humbert n, D. Snider n, C. Jania*, S. Tilley*, D. Metcalfe*, G. Cruse n

co-author countries: United States of America 🇺🇸
author keywords: Mast cell; IgE receptor; MS4A; Allergy; Orai1
MeSH headings : Calcium / metabolism; Calcium Signaling; Cell Degranulation; Cell Line; Cholesterol / metabolism; Fetal Blood / metabolism; Humans; Mast Cells / metabolism; Mast Cells / physiology; Membrane Microdomains / metabolism; Membrane Proteins / metabolism; ORAI1 Protein / metabolism; Phospholipase C gamma / metabolism; Proto-Oncogene Proteins c-kit / metabolism; Receptors, IgE / metabolism; Sequence Homology, Amino Acid; Signal Transduction
Source: ORCID
Added: April 10, 2020

Members of the membrane spanning 4A (MS4A) gene family are clustered around 11q12-13, a region linked to allergy and asthma susceptibility. Other than the known functions of FcεRIβ (MS4A2) and CD20 (MS4A1) in mast cell and B cell signaling, respectively, functional studies for the remaining MS4A proteins are lacking. We thus explored whether MS4A4A, a mast cell expressed homologue of FcεRIβ, has related functions to FcεRIβ in FcεRI signaling. We establish in this study that MS4A4A promotes phosphorylation of PLCγ1, calcium flux and degranulation in response to IgE-mediated crosslinking of FcεRI. We previously demonstrated that MS4A4A promotes recruitment of KIT into caveolin-1-enriched microdomains and signaling through PLCγ1. Caveolin-1 itself is an important regulator of IgE-dependent store-operated Ca2+ entry (SOCE) and promotes expression of the store-operated Ca2+ channel pore-forming unit, Orai1. We thus further report that MS4A4A functions through interaction with caveolin-1 and recruitment of FcεRI and KIT into lipid rafts. In addition to proximal FcεRI signaling, we similarly show that MS4A4A regulates Orai1-mediated calcium entry downstream of calcium release from stores. Both MS4A4A and Orai1 had limited effects with compound 48/80 stimulation, demonstrating some degree of selectivity of both proteins to FcεRI receptor signaling over Mas-related G Protein coupled receptor X2 signaling. Overall, our data are consistent with the conclusion that MS4A4A performs a related function to the homologous FcεRIβ to promote PLCγ1 signaling, SOCE, and degranulation through FcεRI in human mast cells and thus represents a new target in the regulation of IgE-mediated mast cell activation.