Membrane heterogeneities in the formation of B cell receptor-Lyn kinase microclusters and the immune synapse.
Antigen binding to the B cell receptors (BCRs) induces BCR clustering, phosphorylation of BCRs by the Src family kinase Lyn, initiation of signaling, and formation of an immune synapse. We investigated B cells as they first encountered antigen on a membrane using live cell high resolution total internal reflection fluorescence microscopy in conjunction with fluorescence resonance energy transfer. Newly formed BCR microclusters perturb the local membrane microenvironment, leading to association with a lipid raft probe. This early event is BCR intrinsic and independent of BCR signaling. Association of BCR microclusters with membrane-tethered Lyn depends on Lyn activity and persists as microclusters accumulate and form an immune synapse. Membrane perturbation and BCR-Lyn association correlate both temporally and spatially with the transition of microclustered BCRs from a "closed" to an "open" active signaling conformation. Visualization and analysis of the earliest events in BCR signaling highlight the importance of the membrane microenvironment for formation of BCR-Lyn complexes and the B cell immune synapse.
Sohn
Hae Won
HW
Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
Tolar
Pavel
P
Pierce
Susan K
SK
D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism; D001402:B-Lymphocytes / Q000201:enzymology* / Q000276:immunology*; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology*; D031541:Fluorescence Resonance Energy Transfer; D021962:Membrane Microdomains / Q000276:immunology; D051379:Mice; D008856:Microscopy, Fluorescence; D011487:Protein Conformation; D011940:Receptor Aggregation / Q000276:immunology; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D015398:Signal Transduction / Q000276:immunology; D019061:src-Family Kinases / Q000378:metabolism*
D000944:Antigens, Differentiation, B-Lymphocyte; D011947:Receptors, Antigen, B-Cell; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases