Cloning and characterization of a novel mouse myeloid DAP12-associated receptor family.
The presence of a negatively charged residue in the transmembrane domain of DAP12 precludes its cell surface expression in the absence of a partner receptor containing a positive charge in its transmembrane domain. We utilized this property of DAP12 to screen a BALB / c macrophage cDNA library for novel molecules that induce cell surface expression of DAP12. By this method, we cloned a cell surface receptor with a single Ig (V) domain, a transmembrane lysine residue, and a short cytoplasmic domain. By homology screening of BALB / c macrophage libraries, we identified a second cDNA for a highly homologous receptor. These receptors appear to be the mouse orthologues of a recently identified human cDNA, TREM-2, so we have designated the receptors as mouse TREM-2a and TREM-2b. By Northern blotting, transcripts for TREM-2 were found in each of three macrophage cell lines but not in a variety of other hematopoietic cell lines. We further demonstrate that TREM-2a is associated with endogenous DAP12 in macrophage cells, and cross-linking of TREM-2a on the surface of macrophages leads to the release of nitric oxide. Our studies define TREM-2 as a receptor family in mouse macrophages and demonstrate the capacity of these receptors to activate macrophage function through DAP12.
Department of Immunology, VA Medical Center San Francisco, San Francisco, USA. mdaws@itsa.ucsf.edu
M R
MR
Daws
L L
LL
Lanier
W E
WE
Seaman
J C
JC
Ryan
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics; D008264:Macrophages / Q000378:metabolism*; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000096:biosynthesis; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000096:biosynthesis; D011971:Receptors, Immunologic / Q000235:genetics* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D048868:Adaptor Proteins, Signal Transducing; D007136:Immunoglobulins; D008565:Membrane Proteins; D012333:RNA, Messenger; D011971:Receptors, Immunologic; C424124:TREM-2a receptor; C424125:TREM-2b receptor; C110546:TYROBP protein, human; D009569:Nitric Oxide