Anne Chauveau a,b, Anne Aucher a, Philipp Eissmann a, Eric Vivier b,c, and Daniel M. Davis a,1
-Author Affiliations
aDivision of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, United Kingdom;
bCentre d'Immunologie de Marseille–Luminy, Université de la Méditerranée, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche (UMR) 6312, Centre National de la Recherche Scientifique UMR6102, Campus de Luminy, 13288 Marseille, France; and
cHôpital de la Conception, Assistance Publique-Hôpitaux de Marseille, Baille 13005, Marseille, France
Edited by Ronald N. Germain, National Institutes of Health, Bethesda, MD, and accepted by the Editorial Board February 16, 2010 (received for review September 4, 2009)
Abstract
Membrane nanotubes are membranous tethers that physically link cell bodies over long distances. Here, we present evidence that nanotubes allow human natural killer (NK) cells to interact functionally with target cells over long distances. Nanotubes were formed when NK cells contacted target cells and moved apart. The frequency of nanotube formation was dependent on the number of receptor/ligand interactions and increased on NK cell activation. Most importantly, NK cell nanotubes contained a submicron scale junction where proteins accumulated, including DAP10, the signaling adaptor that associates with the activating receptor NKG2D, and MHC class I chain-related protein A (MICA), a cognate ligand for NKG2D, as occurs at close intercellular synapses between NK cells and target cells. Quantitative live-cell fluorescence imaging suggested that MICA accumulated at small nanotube synapses in sufficient numbers to trigger cell activation. In addition, tyrosine-phosphorylated proteins and Vav-1 accumulated at such junctions. Functionally, nanotubes could aid the lysis of distant target cells either directly or by moving target cells along the nanotube path into close contact for lysis via a conventional immune synapse. Target cells moving along the nanotube path were commonly polarized such that their uropods faced the direction of movement. This is the opposite polarization than for normal cell migration, implying that nanotubes can specifically drive target cell movement. Finally, target cells that remained connected to an NK cell by a nanotube were frequently lysed, whereas removing the nanotube using a micromanipulator reduced lysis of these target cells.
Membrane nanotubes are membranous tethers that physically link cell bodies over long distances. Here, we present evidence that nanotubes allow human natural killer (NK) cells to interact functionally with target cells over long distances. Nanotubes were formed when NK cells contacted target cells and moved apart. The frequency of nanotube formation was dependent on the number of receptor/ligand interactions and increased on NK cell activation. Most importantly, NK cell nanotubes contained a submicron scale junction where proteins accumulated, including DAP10, the signaling adaptor that associates with the activating receptor NKG2D, and MHC class I chain-related protein A (MICA), a cognate ligand for NKG2D, as occurs at close intercellular synapses between NK cells and target cells. Quantitative live-cell fluorescence imaging suggested that MICA accumulated at small nanotube synapses in sufficient numbers to trigger cell activation. In addition, tyrosine-phosphorylated proteins and Vav-1 accumulated at such junctions. Functionally, nanotubes could aid the lysis of distant target cells either directly or by moving target cells along the nanotube path into close contact for lysis via a conventional immune synapse. Target cells moving along the nanotube path were commonly polarized such that their uropods faced the direction of movement. This is the opposite polarization than for normal cell migration, implying that nanotubes can specifically drive target cell movement. Finally, target cells that remained connected to an NK cell by a nanotube were frequently lysed, whereas removing the nanotube using a micromanipulator reduced lysis of these target cells.
cell activation immune synapses cytotoxicity cell motility intercellular communication
Footnotes
1To whom correspondence should be addressed. E-mail:d.davis@imperial.ac.uk.
Author contributions: A.C., E.V. and D.M.D. designed research; A.C. and A.A. performed research; P.E. contributed new reagents/analytic tools; A.C. and D.M.D. analyzed data; and A.C. and D.M.D. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. R.N.G. is a guest editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/cgi/content/full/0910074107/DCSupplemental.
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The authors declare no conflict of interest.
This article is a PNAS Direct Submission. R.N.G. is a guest editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/cgi/content/full/0910074107/DCSupplemental.
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