Biochemical and Biophysical Research Communications
Identification of phosphatidylserine as a ligand for the CD300a immunoreceptor
Highlights
► CD300a is a new phosphatidylserine receptor expressed on myeloid cells. ► Phosphatidylserine delivers a signal for recruitment of SHP-1 by CD300a in mast cells. ► The CD300a/phosphatidylserine interaction is blocked by MFG-E8 or anti-CD300a antibody.
Introduction
CD300 is a multigene family consisting of seven genes on human chromosome 17 [1], [2]. CD300 molecules are member of immunoglobulin (Ig)-super family bearing one Ig-like domain in the extracellular portion. The mouse counterparts of CD300 molecules, which were reported to be as myeloid-associated Ig-like receptor (MAIR) [3], [4], [5], [6], [7], [8]/CMRF-35-like molecule (CLM) [9], [10], [11]/leukocyte mono-Ig-like receptor (LMIR) [12], [13], [14]/DIgR [15], [16], were encoded by nine genes on a small segment of mouse chromosome 11, syntenic region of human chromosome 17 [9], [17]. CD300 molecules are preferentially expressed on myeloid cells, including macrophages, neutrophils, dendritic cells (DCs) and/or mast cells, and may regulate activation of these cells. One of the CD300 molecules, CD300a (also called MAIR-I [3], LMIR1 [12], or CLM-8 [9] in mice and IRp60 [18] or CMRF-35H [1] in human), has a long cytoplasmic region containing the consensus immunoreceptor tyrosine-based inhibitory motif (ITIM) sequence. Upon crosslinking with monoclonal antibodies, CD300a inhibits FcεRI-mediated signals, resulting in the suppression of degranulation from human and mouse mast cells in vitro [3], [4], [19], [20]. In addition, CD300a modulates inflammatory responses by myeloid cells [21], [22]. CD300a is also expressed on human, but not mouse, NK cells and involved in cytotoxic function [18], [23]. However, the ligand for CD300a has not been identified and the physiological role of CD300a remained unclear.
In this study, we identified phosphatidylserine (PS), which is exposed on the outer leaflet of the plasma membrane of apoptotic cells, as a ligand for CD300a.
Section snippets
Antibodies, CD300-Fc and MFG-E8
The human and mouse CD300a-specific monoclonal antibodies TX49 (mouse IgG1) and TX41 (rat IgG2a), respectively, were generated in our laboratory, as described previously [3]. The fusion proteins of CD300a and CD300d with the Fc portion of human IgG (CD300a-Fc and CD300d-Fc, respectively) were generated from chimeric cDNA containing the entire extracellular domain of each CD300 and the human IgG1Fc, as described [24]. Milk fat globule EGF factor 8 (MFG-E8) and D89E MFG-E8 containing a point
CD300a binds dead cells
To identify the ligand for CD300a, we generated a chimeric fusion protein of the extracellular portion of CD300a with the Fc portion of human IgG (CD300a-Fc). We used the CD300a-Fc to screen for the expression of a CD300a ligand on hematopoietic cells and tumor cell lines by using flow cytometry. Although the CD300a-Fc did not stain any viable cells tested, we found that CD300a-Fc bound a small population of dead cells. To confirm this observation, Ba/F3 cells were irradiated with UV for 30 min
Discussion
Several receptors for PS are expressed on phagocytes and are involved in clearing apoptotic cells [27], [28], [29]. For example, T cell immunoglobulin- and mucin-domain-containing molecules 4 (TIM-4), TIM-1 and TIM-3 are expressed on macrophages and/or dendritic cells and mediate engulfment of apoptotic cells upon binding PS [30], [31]. Brain-specific angiogenesis inhibitor 1 (BAI1) [32] and stabilin-2 [33], which are expressed on neuron [34] and the sinusoidal endothelial cells of the spleen,
Acknowledgments
We thank S. Mitsuishi for secretarial assistances. This research was supported in part by Grants provided by the Ministry of Education, Culture, Sports, Science and Technology of Japan and by the Program for Promotion of Fundamental Studies in Health Science of the National Institute of Biomedical Innovation (NIBIO), Japan.
References (39)
- et al.
Activation of neutrophils by a novel triggering immunoglobulin-like receptor MAIR-IV
Mol. Immunol.
(2008) - et al.
Identification and characterization of a new pair of immunoglobulin-like receptors LMIR1 and 2 derived from murine bone marrow-derived mast cells
Biochem. Biophys. Res. Commun.
(2003) - et al.
Functional analysis of activating receptor LMIR4 as a counterpart of inhibitory receptor LMIR3
J. Biol. Chem.
(2007) - et al.
DIgR1 A novel membrane receptor of the immunoglobulin gene superfamily, is preferentially expressed by antigen-presenting cells
Biochem. Biophys. Res. Commun.
(2001) - et al.
DIgR2, dendritic cell-derived immunoglobulin receptor 2 is one representative of a family of IgSF inhibitory receptors and mediates negative regulation of dendritic cell-initiated antigen-specific T-cell responses
Blood
(2006) - et al.
Involvement of mast cells in IL-12/23 p40 production is essential for survival from polymicrobial infections
Blood
(2007) - et al.
Reversal of airway inflammation and remodeling in asthma by a bispecific antibody fragment linking CCR3 to CD300a
J. Allergy Clin. Immunol.
(2006) - et al.
Are we ready to downregulate mast cells?
Curr. Opin. Immunol.
(2009) - et al.
The CD300a (IRp60) inhibitory receptor is rapidly up-regulated on human neutrophils in response to inflammatory stimuli and modulates CD32a (FcgammaRIIa) mediated signaling
Mol. Immunol.
(2008) - et al.
CD300a/c regulate type I interferon and TNF-alpha secretion by human plasmacytoid dendritic cells stimulated with TLR7 and TLR9 ligands
Blood
(2008)
New phosphatidylserine receptors: clearance of apoptotic cells and more
Dev. Cell
TIM-1 and TIM-4 glycoproteins bind phosphatidylserine and mediate uptake of apoptotic cells
Immunity
Brain-specific angiogenesis inhibitor 1 (BAI1) is expressed in human cerebral neuronal cells
Neurosci. Res.
Expression, processing, and glycosaminoglycan binding activity of the recombinant human 315-kDa hyaluronic acid receptor for endocytosis (HARE)
J. Biol. Chem.
Cell adhesion to phosphatidylserine mediated by a product of growth arrest-specific gene 6
J. Biol. Chem.
The CMRF-35H gene structure predicts for an independently expressed member of an ITIM/ITAM pair of molecules localized to human chromosome 17
Tissue Antigens
The gene encoding the immunoregulatory signaling molecule CMRF-35A localized to human chromosome 17 in close proximity to other members of the CMRF-35 family
Tissue Antigens
Paired activating and inhibitory immunoglobulin-like receptors, MAIR-I and MAIR-II, regulate mast cell and macrophage activation
J. Exp. Med.
Requirement of the tyrosines at residues 258 and 270 of MAIR-I in inhibitory effect on degranulation from basophilic leukemia RBL-2H3
Int. Immunol.
Cited by (65)
Efferocytosis: An accomplice of cancer immune escape
2023, Biomedicine and PharmacotherapyThe secretome of irradiated peripheral blood mononuclear cells attenuates activation of mast cells and basophils
2022, eBioMedicineCitation Excerpt :Similarly, lipid pre-treatment prevented basophil activation following α-IgE to a similar extent as PBMCsec (P=0.0207 PBMCsec versus medium and P=0.6606 PBMCsec versus lipids, [ANOVA and Dunnett's multiple comparisons test]; Figure 6c) and even stronger than PBMCsec after stimulation with Bet v 1 (P=0.0017 PBMCsec versus medium and P=0.0038 PBMCsec versus lipids, [ANOVA and Dunnett's multiple comparisons test]; Figure 6d, Supplemental Figure S16). Previously, an inhibitory effect of phosphatidylserine (PS) on basophils via CD300a has been reported.46,51 Since γ-irradiated PBMCs, the source of PBMCsec, express PS on their surface,17,52 we screened PBMCsec for the presence of PS analytes by lipidomics.
Positive and negative roles of lipids in mast cells and allergic responses
2021, Current Opinion in ImmunologyAutonomous regulation of IgE-mediated mast cell degranulation and immediate hypersensitivity reaction by an inhibitory receptor CD300a
2019, Journal of Allergy and Clinical Immunology