Myeloid immune checkpoint ILT3/LILRB4/gp49B can co-tether fibronectin with integrin on macrophages. (11th June 2022)

• Record Type: Journal Article
• Authors: Itoi, So; Takahashi, Naoyuki; Saito, Haruka; Miyata, Yusuke; Su, Mei-Tzu; Kezuka, Dai; Itagaki, Fumika; Endo, Shota; Fujii, Hiroshi; Harigae, Hideo; Sakamoto, Yuzuru; Takai, Toshiyuki
• Is Part Of: International immunology. Volume 34:Number 8(2022)
• Page Start: 435
• Page End: 444
• Publication Date: 2022-06-11
• Subjects: extracellular matrix -- focal adhesion kinase -- myeloid checkpoint -- spleen tyrosine kinase; Immunology -- Periodicals; 616.079
• DOI: 10.1093/intimm/dxac023
• Languages: English
• ISSNs: 0953-8178

Abstract

Abstract: LILRB4 (B4, also known as ILT3/CD85k) is an immune checkpoint of myeloid lineage cells, albeit its mode of function remains obscure. Our recent identification of a common ligand for both human B4 and its murine ortholog gp49B as the fibronectin (FN) N-terminal 30 kDa domain poses the question of how B4/gp49B regulate cellular activity upon recognition of FN in the plasma and/or the extracellular matrix. Since FN in the extracellular matrix is tethered by FN-binding integrins, we hypothesized that B4/gp49B would tether FN in cooperation with integrins on the cell surface, thus they should be in close vicinity to integrins spatially. This scenario suggests a mode of function of B4/gp49B by which the FN-induced signal is regulated. The FN pull-down complex was found to contain gp49B and integrin β 1 in bone marrow-derived macrophages. The confocal fluorescent signals of the three molecules on the intrinsically FN-tethering macrophages were correlated to each other. When FN-poor macrophages adhered to culture plates, the gp49–integrin β 1 signal correlation increased at the focal adhesion, supporting the notion that gp49B and integrin β 1 become spatially closer to each other there. Adherence of RAW264.7 and THP-1 cells to immobilized FN induced phosphorylation of spleen tyrosine kinase, whose level was augmented under B4/gp49B deficiency. Thus, we concluded that B4/gp49B can co-tether FN in cooperation with integrin in the cis configuration on the same cell, forming a B4/gp49B–FN–integrin triplet as a regulatory unit of a focal adhesion-dependent pro-inflammatory signal in macrophages. Abstract : B4 and integrins co-tether fibronectin on macrophages Graphical Abstract: