NK cell CD94/NKG2A inhibitory receptors are internalized and recycle independently of inhibitory signaling processes

F Borrego, J Kabat, TB Sanni… - The Journal of …, 2002 - journals.aai.org
F Borrego, J Kabat, TB Sanni, JE Coligan
The Journal of Immunology, 2002journals.aai.org
Abstract Human CD94/NKG2A is an inhibitory receptor that recognizes HLA-E and is
expressed by NK cells and a subset of T cells. We have analyzed the cellular trafficking of
the CD94/NKG2A receptor using the NKL cell line and peripheral blood NK cells. Flow
cytometric, confocal microscopic, and biochemical analyses show that CD94/NKG2A
continuously recycles in an active process that requires the cytoskeleton between the cell
surface and intracellular compartments that are distinguishable from recycling compartments …
Abstract
Human CD94/NKG2A is an inhibitory receptor that recognizes HLA-E and is expressed by NK cells and a subset of T cells. We have analyzed the cellular trafficking of the CD94/NKG2A receptor using the NKL cell line and peripheral blood NK cells. Flow cytometric, confocal microscopic, and biochemical analyses show that CD94/NKG2A continuously recycles in an active process that requires the cytoskeleton between the cell surface and intracellular compartments that are distinguishable from recycling compartments used by well-characterized receptors, such as transferrin receptor (CD71). CD94/NKG2A, an inhibitory receptor, traffics differently from the closely related CD94/NKG2C molecule, an activating receptor. Using transfection/expression analyses of wild-type and mutant CD94/NKG2A molecules in the HLA-E negative rat basophilic cell line RBL-2H3, we demonstrate that CD94/NKG2A internalization is independent of ligand cross-linking or the presence of functional immunoreceptor tyrosine-based inhibition motifs. Thus, the mechanisms that control cell surface homeostasis of CD94/NKG2A are independent of functional signaling.
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