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Signal regulated localisation of a mutagenic protein complex at the Igh locus
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
2015 (English)In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 282, 13-13 p.Article in journal, Meeting abstract (Other academic) Published
Abstract [en]

Our system to produce antibodies is critical for our survival against numerous infections, but it causes also many tumors. B-lymphocytes can modify their immunoglobulin (Ig) genes to generate specific antibodies with a new isotype and enhanced affinity against an antigen. Activation-induced cytidine deaminase (AID) is the key mutagenic enzyme that initiates these processes by deaminating cytosine to uracil. How somatic hypermutation (SH) and class switch recombination (CSR) are targeted is key to understanding the defect DNA integrity in lymphomas and also in other tumors where inflammatory signals aberrantly induces AID. The trans-acting factors mediating specific targeting of AID and thereby SH and CSR have remained elusive. Here we show that mutant E2A with defect inhibition by the Ca2+sensor protein calmodulin results in reduced B cell receptor- (BCR-), IL4-plus CD40 ligand-stimulated CSR to IgE and instead aberrant CSR. AID is shown to be together with the transcription factors E2A, PAX5 and IRF4 in a complex on key sequences of the Igh locus in activated mouse splenic B cells. Calmodulin shows proximity with each of them after BCR stimulation. Direct protein-protein interactions enable formation of the complexes. BCR signaling reduces binding of the proteins to some of the target sites on the Igh locus, and calmodulin resistance of E2A blocks reduction of binding to these target sites and increases binding to other target sites. Thus, E2A, AID, PAX5 and IRF4 are components of a CSR and SH complex that is redistributed on the IgH gene by BCR signaling through calmodulin binding.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2015. Vol. 282, 13-13 p.
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Identifiers
URN: urn:nbn:se:umu:diva-111161DOI: 10.1111/febs.13320ISI: 000362570600032OAI: oai:DiVA.org:umu-111161DiVA: diva2:868396
Conference
40th Congress of the Federation-of-European-Biochemical-Societies (FEBS) - The Biochemical Basis of Life, Berlin, July 4-9, 2015
Note

Supplement: 1

Special Issue: SI

Meeting Abstract: P02-003-SH

Available from: 2015-11-10 Created: 2015-11-06 Last updated: 2015-11-10Bibliographically approved

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Hauser, JannekGrundström, ChristineKumar, RameshGrundström, Thomas
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Department of Molecular Biology (Faculty of Medicine)
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The FEBS Journal
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)

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