A common signaling pathway leading to degranulation in mast cells and its regulation by CCR1‐ligand. Issue 6 (6th February 2020)

• Record Type: Journal Article
• Authors: Chang, Hyeun Wook; Kanegasaki, Shiro; Jin, Fansi; Deng, Yifeng; You, Zhiwei; Chang, Jae‐Hoon; Kim, Dong Young; Timilshina, Maheshwor; Kim, Jae‐Ryong; Lee, Youn Ju; Toyama‐Sorimachi, Noriko; Tsuchiya, Tomoko
• Is Part Of: Allergy. Volume 75:Issue 6(2020)
• Page Start: 1371
• Page End: 1381
• Publication Date: 2020-02-06
• Subjects: CCR1 -- FcεRI -- KIT -- SHP‐1 -- TLR4; Allergy -- Periodicals; 616.97
• DOI: 10.1111/all.14186
• Languages: English
• ISSNs: 0105-4538

Abstract

Abstract: Background: Signal transduction pathways mediated by various receptors expressed on mast cells are thought to be complex, and inhibitory signals that turn off activating signals are not known. Methods: Upstream signaling cascades mediated by several known receptors in bone marrow‐derived mast cells that lead to degranulation and mediator release were studied by immunoblotting and immunoprecipitation. Small interfering RNAs and knockout mice were used to confirm findings. Results: All ligands tested including IgE/Ag, SCF, HSP70, CCL3, and its valiant eMIP induced phosphorylation of linker for activation of T cells (LAT), which triggered their receptor‐mediated downstream signaling cascades that controlled degranulation and mediator release. Phosphorylation of lymphocyte‐specific protein kinase (Lck) was induced by each ligand, which commonly played an indispensable role in LAT phosphorylation. In contrast, phosphorylation of spleen tyrosine kinase was additionally induced in cells stimulated only with IgE/Ag and SCF, which is also associated with LAT phosphorylation in part. Degranulation and mediator release induced by IgE/Ag, SCF, or HSP70 were enhanced by nanomolar doses of CCR1 ligands CCL3 and eMIP via enhanced LAT phosphorylation. On the other hand, micromolar doses of CCR1 ligand inhibited degranulation and mediator release from mast cells stimulated with IgE/Ag, SCF, or HSP70 by de‐phosphorylation of phosphorylated Lck with Src homology region 2 domain‐containing phosphatase‐1. Conclusions: Linker for activation of T cells plays a central role in signal transduction pathways in mast cells stimulated with any ligand tested. Dose‐dependent alternate costimulation and inhibition of CCR1 ligands in IgE/Ag‐, SCF‐, or HSP70‐stimulated mast cells occur at the level of Lck‐LAT phosphorylation. Abstract : Binding of IgE/Ag, SCF, HSP70, and eMIP/CCL3 to their receptors induces Lck phosphorylation, which in turn phosphorylates LAT. Phospho‐LAT triggers phosphorylation of PLC, PI3K, and downstream signaling proteins leading to degranulation and mediator release. All receptors are internalized with the aid of phospho‐Lck. Activated by micromolar doses of eMIP/CCL3 or by A770041, SHP‐1 dephosphorylates phospho‐Lck, whereby receptor recycling, degranulation and mediator release are terminated. Abbreviations: A770041, a selective inhibitor of Lck; CCL3, C‐C motif chemokine ligand 3; eMIP, a 69‐amino acid variant of human CCL3; HSP70, heat shock protein 70; Lck, lymphocyte‐specific protein tyrosine kinase; LAT, linker for activation of T cells; PI3K: phosphatidylinositol 3‐kinase; PLC?: phospholipase C?; SCF; stem cell factor; SHP‐1: Src homology region 2 domain‐containing phosphatase‐1