Lipid rafts are required for efficient signal transduction by CD1d.
Plasma membranes of eukaryotic cells are not uniform, possessing distinct cholesterol- and sphingolipid-rich lipid raft microdomains which constitute critical sites for signal transduction through various immune cell receptors and their co-receptors. CD1d is a conserved family of major histocompatibility class I-like molecules, which has been established as an important factor in lipid antigen presentation to natural killer T (NKT) cells. Unlike conventional T cells, recognition of CD1d by the T cell receptor (TCR) of NKT cells does not require CD4 or CD8 co-receptors, which are critical for efficient TCR signaling. We found that murine CD1d (mCD1d) was constitutively present in the plasma membrane lipid rafts on antigen presenting cells, and that this restricted localization was critically important for efficient signal transduction to the target NKT cells, at low ligand densities, even without the involvement of co-receptors. Further our results indicate that there may be additional regulatory molecule(s), co-located in the lipid raft with mCD1d for NKT cell signaling.
Park
Yoon-Kyung
YK
Graduate School of Life Sciences and Biotechnology, Korea University, Anam-Dong, Sungbuk-Ku, Seoul 136-701, Republic of Korea.
Lee
Joong-Won
JW
Ko
Young-Gyu
YG
Hong
Seokmann
S
Park
Se-Ho
SH
D000818:Animals; D018949:Antigens, CD1 / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D015536:Down-Regulation; D007110:Immunity, Active / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism; D015471:Leukemia, Basophilic, Acute / Q000378:metabolism; D008024:Ligands; D021962:Membrane Microdomains / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D051381:Rats; D015398:Signal Transduction
D018949:Antigens, CD1; D008024:Ligands