An activating and inhibitory signal from an inhibitory receptor LMIR3/CLM-1: LMIR3 augments lipopolysaccharide response through association with FcRgamma in mast cells.
Leukocyte mono-Ig-like receptor 3 (LMIR3) is an inhibitory receptor mainly expressed in myeloid cells. Coengagement of Fc epsilonRI and LMIR3 impaired cytokine production in bone marrow-derived mast cells (BMMCs) induced by Fc epsilonRI crosslinking alone. Mouse LMIR3 possesses five cytoplasmic tyrosine residues (Y241, Y276, Y289, Y303, Y325), among which Y241 and Y289 (Y241/289) or Y325 fit the consensus sequence of ITIM or immunotyrosine-based switch motif (ITSM), respectively. The inhibitory effect was abolished by the replacement of Y325 in addition to Y241/289 with phenylalanine (Y241/189/325/F) in accordance with the potential of Y241/289/325 to cooperatively recruit Src homology region 2 domain-containing phosphatase 1 (SHP)-1 or SHP-2. Intriguingly, LMIR3 crosslinking alone induced cytokine production in BMMCs expressing LMIR3 (Y241/276/289/303/325F) mutant as well as LMIR3 (Y241/289/325F). Moreover, coimmunoprecipitation experiments revealed that LMIR3 associated with ITAM-containing FcRgamma. Analysis of FcRgamma-deficient BMMCs demonstrated that both Y276/303 and FcRgamma played a critical role in the activating function of this inhibitory receptor. Importantly, LMIR3 crosslinking enhanced cytokine production of BMMCs stimulated by LPS, while suppressing production stimulated by other TLR agonists or stem cell factor. Thus, an inhibitory receptor LMIR3 has a unique property to associate with FcRgamma and thereby functions as an activating receptor in concert with TLR4 stimulation.
Izawa
Kumi
K
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
Kitaura
Jiro
J
Yamanishi
Yoshinori
Y
Matsuoka
Takayuki
T
Kaitani
Ayako
A
Sugiuchi
Masahiro
M
Takahashi
Mariko
M
Maehara
Akie
A
Enomoto
Yutaka
Y
Oki
Toshihiko
T
Takai
Toshiyuki
T
Kitamura
Toshio
T
D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D000818:Animals; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008407:Mast Cells / Q000276:immunology*; D051379:Mice; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000378:metabolism; D017452:Receptors, IgG / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D014443:Tyrosine / Q000235:genetics
C482560:CLM-1 protein, mouse; D008070:Lipopolysaccharides; D017452:Receptors, IgG; D011971:Receptors, Immunologic; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D014443:Tyrosine; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; C516725:Ptpn11 protein, mouse