Leukocyte-associated immunoglobulin-like receptor 1 inhibits T-cell signaling by decreasing protein phosphorylation in the T-cell signaling pathway

Jeoung-Eun Park,David D Brand,Edward F Rosloniec,Ae-Kyung Yi,John M Stuart,Andrew H Kang,Linda K Myers

doi:10.1074/jbc.ra119.011150

Abstract

Multiple observations implicate T-cell dysregulation as a central event in the pathogenesis of rheumatoid arthritis. Here, we investigated mechanisms for suppressing T-cell activation via the inhibitory receptor leukocyte-associated immunoglobulin-like receptor 1 (LAIR-1). To determine how LAIR-1 affects T-cell receptor (TCR) signaling, we compared 1) T cells from LAIR-1-sufficient and -deficient mice, 2) Jurkat cells expressing either LAIR-1 mutants or C-terminal Src kinase (CSK) mutants, and 3) T cells from mice that contain a CSK transgene susceptible to chemical inhibition. Our results indicated that LAIR-1 engagement by collagen or by complement C1q (C1Q, which contains a collagen-like domain) inhibits TCR signaling by decreasing the phosphorylation of key components in the canonical T-cell signaling pathway, including LCK proto-oncogene SRC family tyrosine kinase (LCK), LYN proto-oncogene SRC family tyrosine kinase (LYN), ζ chain of T-cell receptor-associated protein kinase 70 (ZAP-70), and three mitogen-activated protein kinases (extracellular signal-regulated kinase, c-Jun N-terminal kinase 1/2, and p38). The intracellular region of LAIR-1 contains two immunoreceptor tyrosine-based inhibition motifs that are both phosphorylated by LAIR-1 activation, and immunoprecipitation experiments revealed that Tyr-251 in LAIR-1 binds CSK. Using CRISPR/Cas9-mediated genome editing, we demonstrate that CSK is essential for the LAIR-1-induced inhibition of the human TCR signal transduction. T cells from mice that expressed a PP1 analog-sensitive form of CSK (CskAS) corroborated these findings, and we also found that Tyr-251 is critical for LAIR-1's inhibitory function. We propose that LAIR-1 activation may be a strategy for controlling inflammation and may offer a potential therapeutic approach for managing autoimmune diseases.

Highlights

Multiple observations implicate T-cell dysregulation as a central event in the pathogenesis of rheumatoid arthritis
We have previously shown that activation of LAIR-1 can prevent collagen-induced autoimmune arthritis (CIA) [2]
To investigate whether tyrosine residues in inhibition motifs (ITIMs) are critical for LAIR-1 function and to clarify which tyrosine is required for the inhibition of the T cell, we developed mutant LAIR-1 constructs in which individual tyrosine residues were replaced by phenylalanine

Summary

Introduction

Multiple observations implicate T-cell dysregulation as a central event in the pathogenesis of rheumatoid arthritis. We investigated mechanisms for suppressing T-cell activation via the inhibitory receptor leukocyte-associated immunoglobulinlike receptor 1 (LAIR-1). Cells may express multiple inhibitory receptors, some individual receptors are important in the regulation of particular immune functions [1]. One such receptor is leukocyte-associated Ig-like receptor 1 (LAIR-1) or CD305. LAIR-1 contributes to the regulation of the immune system by binding to extracellular ligands and delivering a signal to immune cells. LAIR-1 has an extracellular binding domain coupled to a cytoplasmic tail containing two immunoreceptor tyrosine-based inhibition motifs (ITIMs). We have previously shown that activation of LAIR-1 can prevent collagen-induced autoimmune arthritis (CIA) [2]. This study explores the mechanism by which LAIR-1 modifies T-cell function and prevents signaling through the TCR

Results

Discussion

Conclusion