title: Negative feedback regulation of antigen receptors through calmodulin inhibition of E2A.
abstract: Signaling from the BCR is used to judge Ag-binding strengths of the Abs of B cells. BCR signaling enables the selection for successive improvements in the Ag affinity over an extremely broad range of affinities during somatic hypermutation. We show that the mouse BCR is subject to general negative feedback regulation of the receptor proteins, as well as many coreceptors and proteins in signal pathways from the receptor. Thus, the BCR can downregulate itself, which can enable sensitive detection of successive improvements in the Ag affinity over a very large span of affinities. Furthermore, the feedback inhibition of the BCR signalosome and most of its proteins, as well as most other regulations of genes by BCR stimulation, is to a large extent through inhibition of the transcription factor E2A by Ca(2+)/calmodulin.
authors.affiliation: Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Jiyoti
authors.initials: J
authors.lastname: Verma-Gaur
authors.forename: Jannek
authors.initials: J
authors.lastname: Hauser
authors.forename: Thomas
authors.initials: T
authors.lastname: Grundström
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000276:immunology / Q000378:metabolism*; D015153:Blotting, Western; D002147:Calmodulin / Q000276:immunology / Q000378:metabolism*; D002469:Cell Separation; D025461:Feedback, Physiological / Q000502:physiology*; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D060888:Real-Time Polymerase Chain Reaction; D011947:Receptors, Antigen, B-Cell / Q000276:immunology / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D002147:Calmodulin; D011947:Receptors, Antigen, B-Cell; C075668:Tcf3 protein, mouse