Human CD300C delivers an Fc receptor-γ-dependent activating signal in mast cells and monocytes and differs from CD300A in ligand recognition.
CD300C is highly homologous with an inhibitory receptor CD300A in an immunoglobulin-like domain among the human CD300 family of paired immune receptors. To clarify the precise expression and function of CD300C, we generated antibodies discriminating between CD300A and CD300C, which recognized a unique epitope involving amino acid residues CD300A(F56-L57) and CD300C(L63-R64). Notably, CD300C was highly expressed in human monocytes and mast cells. Cross-linking of CD300C by its specific antibody caused cytokine/chemokine production of human monocytes and mast cells. Fc receptor γ was indispensable for both efficient surface expression and activating functions of CD300C. To identify a ligand for CD300A or CD300C, we used reporter cell lines expressing a chimera receptor harboring extracellular CD300A or CD300C and intracellular CD3ζ, in which its unknown ligand induced GFP expression. Our results indicated that phosphatidylethanolamine (PE) among the lipids tested and apoptotic cells were possible ligands for both CD300C and CD300A. PE and apoptotic cells more strongly induced GFP expression in the reporter cells through binding to extracellular CD300A as compared with CD300C. Differential recognition of PE by extracellular CD300A and CD300C depended on different amino acid residues CD300A(F56-L57) and CD300C(L63-R64). Interestingly, GFP expression induced by extracellular CD300C-PE binding in the reporter cells was dampened by co-expression of full-length CD300A, indicating the predominance of CD300A over CD300C in PE recognition/signaling. PE consistently failed to stimulate cytokine production in monocytes expressing CD300C with CD300A. In conclusion, specific engagement of CD300C led to Fc receptor γ-dependent activation of mast cells and monocytes.
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Mariko
M
Takahashi
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Kumi
K
Izawa
Department of Molecular Cell Immunology and Allergology, Nihon University School of Medicine, 30-1 Oyaguchikami-cho, Itabashi, Tokyo 173-8610, Japan; Research Unit for Allergy, RIKEN Research Center for Allergy and Immunology, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
Jun-Ichi
JI
Kashiwakura
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Yoshinori
Y
Yamanishi
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Yutaka
Y
Enomoto
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Ayako
A
Kaitani
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Akie
A
Maehara
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Masamichi
M
Isobe
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Shinichi
S
Ito
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Toshihiro
T
Matsukawa
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Fumio
F
Nakahara
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan; Division of Stem Cell Signaling, Center for Stem Cell Biology and Regenerative Medicine, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Toshihiko
T
Oki
ACTGen Inc., 15-502, Akaho, Komagane-shi, Nagano-ken, 399-4117, Japan.
Masunori
M
Kajikawa
Department of Molecular Cell Immunology and Allergology, Nihon University School of Medicine, 30-1 Oyaguchikami-cho, Itabashi, Tokyo 173-8610, Japan.
Chisei
C
Ra
Department of Molecular Cell Immunology and Allergology, Nihon University School of Medicine, 30-1 Oyaguchikami-cho, Itabashi, Tokyo 173-8610, Japan.
Yoshimichi
Y
Okayama
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan; Division of Stem Cell Signaling, Center for Stem Cell Biology and Regenerative Medicine, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan. Electronic address: kitamura@ims.u-tokyo.ac.jp.
Toshio
T
Kitamura
Division of Cellular Therapy, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan. Electronic address: kitaura-tky@umin.ac.jp.
Jiro
J
Kitaura
D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism / Q000502:physiology*; D016207:Cytokines / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005786:Gene Expression Regulation; D018922:HL-60 Cells; D006801:Humans; D007107:Immune System; D019169:Jurkat Cells; D020014:K562 Cells; D008024:Ligands; D008407:Mast Cells / Q000166:cytology / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000166:cytology / Q000378:metabolism*; D041681:NIH 3T3 Cells; D010587:Phagocytosis; D051381:Rats; D017452:Receptors, IgG / Q000378:metabolism*; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D020298:U937 Cells
D000954:Antigens, Surface; C444139:CD300C protein, human; D016207:Cytokines; D008024:Ligands; D008562:Membrane Glycoproteins; D017452:Receptors, IgG