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Grundström, Thomas
Publications (10 of 42) Show all publications
Grundström, C., Kumar, A., Priya, A., Negi, N. & Grundström, T. (2018). ETS1 and PAX5 transcription factors recruit AID to Igh DNA. European Journal of Immunology, 48(10), 1687-1697
Open this publication in new window or tab >>ETS1 and PAX5 transcription factors recruit AID to Igh DNA
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2018 (English)In: European Journal of Immunology, ISSN 0014-2980, E-ISSN 1521-4141, Vol. 48, no 10, p. 1687-1697Article in journal (Refereed) Published
Abstract [en]

B lymphocytes optimize antibody responses by class switch recombination (CSR), which changes the expressed constant region exon of the immunoglobulin heavy chain (IgH), and by somatic hypermutation (SH) that introduces point mutations in the variable regions of the antibody genes. Activation-induced cytidine deaminase (AID) is the key mutagenic enzyme that initiates both these antibody diversification processes by deaminating cytosine to uracil. Here we asked the question if transcription factors can mediate the specific targeting of the antibody diversification by recruiting AID. We have recently reported that AID is together with the transcription factors E2A, PAX5 and IRF4 in a complex on key sequences of the Igh locus. Here we report that also ETS1 is together with AID in this complex on key sequences of the Igh locus in splenic B cells of mice. Furthermore, we show that both ETS1 and PAX5 can directly recruit AID to DNA sequences from the Igh locus with the specific binding site for the transcription factor. Taken together, our findings support the notion of a targeting mechanism for the selective diversification of antibody genes with limited genome wide mutagenesis by recruitment of AID by PAX5 and ETS1 in a transcription factor complex.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
Activation-induced cytidine deaminase, Class switch recombination, Protein interactions, Somatic hypermutation, Transcription factors
National Category
Immunology in the medical area
Identifiers
urn:nbn:se:umu:diva-152886 (URN)10.1002/eji.201847625 (DOI)000446431600008 ()30089192 (PubMedID)
Funder
Swedish Cancer SocietySwedish Research Council
Available from: 2018-10-31 Created: 2018-10-31 Last updated: 2018-10-31Bibliographically approved
Kumar, A., Priya, A., Ahmed, T., Grundström, C., Negi, N. & Grundström, T. (2018). Regulation of the DNA Repair Complex during Somatic Hypermutation and Class-Switch Recombination. Journal of Immunology, 200(12), 4146-4156
Open this publication in new window or tab >>Regulation of the DNA Repair Complex during Somatic Hypermutation and Class-Switch Recombination
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2018 (English)In: Journal of Immunology, ISSN 0022-1767, E-ISSN 1550-6606, Vol. 200, no 12, p. 4146-4156Article in journal (Refereed) Published
Abstract [en]

B lymphocytes optimize Ab responses by somatic hypermutation (SH), which introduces pointmutations in the variable regions of the Ab genes and by class-switch recombination (CSR), which changes the expressed C region exon of the IgH. These Ab diversification processes are initiated by the deaminating enzyme activation-induced cytidine deaminase followed by many DNA repair enzymes, ultimately leading to deletions and a high mutation rate in the Ab genes, whereas DNA lesions made by activation-induced cytidine deaminase are repaired with low error rate on most other genes. This indicates an advanced regulation of DNA repair. In this study, we show that initiation of Ab diversification in B lymphocytes of mouse spleen leads to formation of a complex between many proteins in DNA repair. We show also thatBCR activation, which signals the end of successful SH, reduces interactions between some proteins in the complex and increases other interactions in the complex with varying kinetics. Furthermore, we show increased localization of SH-and CSR-coupled proteins on switch regions of the Igh locus upon initiation of SH/CSR and differential changes in the localization upon BCR signaling, which terminates SH. These findings provide early evidence for a DNA repair complex or complexes that may be of functional significance for carrying out essential roles in SH and/or CSR in B cells.

Place, publisher, year, edition, pages
American Association of Immunologists, 2018
National Category
Immunology in the medical area
Identifiers
urn:nbn:se:umu:diva-151570 (URN)10.4049/jimmunol.1701586 (DOI)000442386300029 ()29728513 (PubMedID)
Funder
Swedish Cancer SocietySwedish Research Council
Available from: 2018-09-10 Created: 2018-09-10 Last updated: 2018-09-10Bibliographically approved
Hauser, J., Grundström, C., Kumar, R. & Grundström, T. (2016). Regulated localization of an AID complex with E2A, PAX5 and IRF4 at the Igh locus. Molecular Immunology, 80, 78-90
Open this publication in new window or tab >>Regulated localization of an AID complex with E2A, PAX5 and IRF4 at the Igh locus
2016 (English)In: Molecular Immunology, ISSN 0161-5890, E-ISSN 1872-9142, Vol. 80, p. 78-90Article in journal (Refereed) Published
Abstract [en]

Activation-induced cytidine deaminase (AID) is the key mutagenic enzyme that initiates somatic hypermutation (SH) and class switch recombination (CSR) by deaminating cytosine to uracil. The targeting of AID and therefore SH and CSR to Ig genes is a central process of the immune system, but the trans-acting factors mediating the specific targeting have remained elusive. Here we show that defective calmodulin inhibition of the transcription factor E2A after activation of the B cell receptor (BCR) leads to reduced BCR, IL4 plus CD40 ligand stimulated CSR to IgE and instead CSR to other Ig classes. AID that initiates CSR is shown to be in a complex with the transcription factors E2A, PAX5 and IRF4 on key sequences of the Igh locus. Calmodulin shows proximity with each of them after BCR stimulation. BCR signaling reduces binding of the proteins to some of the target sites on the Igh locus, and calmodulin resistance of E2A blocks these reductions. AID binds directly to the bHLH domain of E2A and to the PD domain of PAX5. E2A, AID, PAX5 and IRF4 are components of a CSR complex that is redistributed on the Igh locus by BCR signaling through calmodulin binding.

Keywords
Class switch recombination, Antibodies, Activation-induced cytidine deaminase, Transcription factors, E2A, Calmodulin
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-130546 (URN)10.1016/j.molimm.2016.10.014 (DOI)000395847100010 ()2-s2.0-84994651161 (Scopus ID)
Available from: 2017-01-23 Created: 2017-01-23 Last updated: 2018-06-09Bibliographically approved
Grundström, T., Hauser, J., Grundström, C., Kumar, A., Priya, A. & Kumar, R. (2016). Regulation of diversification and affinity maturation of antibodies. International Journal of Molecular Medicine, 38, S43-S43
Open this publication in new window or tab >>Regulation of diversification and affinity maturation of antibodies
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2016 (English)In: International Journal of Molecular Medicine, ISSN 1107-3756, E-ISSN 1791-244X, Vol. 38, p. S43-S43Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Spandidos, 2016
National Category
Basic Medicine
Identifiers
urn:nbn:se:umu:diva-126770 (URN)000383733000154 ()
Note

Supplement: 1, Meeting Abstract: 253

Available from: 2016-10-18 Created: 2016-10-13 Last updated: 2018-06-09Bibliographically approved
Grundström, T., Hauser, J., Grundström, C., Kumar, R. & Ahmed, T. (2015). Mechanisms controlling diversification and affinity maturation of antibodies. International Journal of Molecular Medicine, 36, S43-S43
Open this publication in new window or tab >>Mechanisms controlling diversification and affinity maturation of antibodies
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2015 (English)In: International Journal of Molecular Medicine, ISSN 1107-3756, E-ISSN 1791-244X, Vol. 36, p. S43-S43Article in journal, Meeting abstract (Other academic) Published
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-110605 (URN)000361863000157 ()
Note

Supplement: 1 Meeting Abstract: 256

Available from: 2015-10-28 Created: 2015-10-23 Last updated: 2018-06-07Bibliographically approved
Hauser, J., Grundström, C., Kumar, R. & Grundström, T. (2015). Signal regulated localisation of a mutagenic protein complex at the Igh locus. Paper presented at 40th Congress of the Federation-of-European-Biochemical-Societies (FEBS) - The Biochemical Basis of Life, Berlin, July 4-9, 2015. The FEBS Journal, 282, 13-13
Open this publication in new window or tab >>Signal regulated localisation of a mutagenic protein complex at the Igh locus
2015 (English)In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 282, p. 13-13Article 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
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Identifiers
urn:nbn:se:umu:diva-111161 (URN)10.1111/febs.13320 (DOI)000362570600032 ()
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: 2018-06-07Bibliographically approved
diva2:712320
Open this publication in new window or tab >>Allelic Exclusion of IgH through Inhibition of E2A in a VDJ Recombination Complex
2014 (English)In: Journal of Immunology, ISSN 0022-1767, E-ISSN 1550-6606, Vol. 192, no 5, p. 2460-2470Article in journal (Refereed) Published
Abstract [en]

A key feature of the immune system is the paradigm that one lymphocyte has only one Ag specificity that can be selected for or against. This requires that only one of the alleles of genes for AgR chains is made functional. However, the molecular mechanism of this allelic exclusion has been an enigma. In this study, we show that B lymphocytes with E2A that cannot be inhibited by calmodulin are dramatically defective in allelic exclusion of the IgH locus. Furthermore, we provide data supporting that E2A, PAX5, and the RAGs are in a VDJ recombination complex bound to key sequences on the Igh gene. We show that pre-BCR activation releases the VDJ recombination complex through calmodulin binding to E2A. We also show that pre-BCR signaling downregulates several components of the recombination machinery, including RAG1, RAG2, and PAX5, through calmodulin inhibition of E2A.

Place, publisher, year, edition, pages
Bethesda: American Association of Immunologists, 2014
National Category
Immunology
Identifiers
urn:nbn:se:umu:diva-87877 (URN)10.4049/jimmunol.1302216 (DOI)000332701400050 ()24470503 (PubMedID)
Available from: 2014-04-14 Created: 2014-04-14 Last updated: 2018-06-08Bibliographically approved
Wallenius, A., Hauser, J., Aas, P. A., Sarno, A., Kavli, B., Krokan, H. E. & Grundström, T. (2014). Expression and recruitment of uracil-DNA glycosylase are regulated by E2A during antibody diversification. Molecular Immunology, 60(1), 23-31
Open this publication in new window or tab >>Expression and recruitment of uracil-DNA glycosylase are regulated by E2A during antibody diversification
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2014 (English)In: Molecular Immunology, ISSN 0161-5890, E-ISSN 1872-9142, Vol. 60, no 1, p. 23-31Article in journal (Refereed) Published
Abstract [en]

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), which is positively regulated by the transcription factor E2A, is the key enzyme that initiates these processes by deaminating cytosine to uracil in Ig genes. Nuclear uracil-DNA glycosylase (UNG2) is subsequently required for uracil processing in the generation of high affinity antibodies of different isotypes. Here we show that the transcription factor E2A binds to the UNG2 promoter and represses UNG2 expression. Inhibition of E2A by binding of Ca2+-activated calmodulin alleviates this repression. Furthermore, we demonstrate that UNG2 preferentially accumulates in regions of the Ig heavy chain (IgH) gene containing AID hotspots. Calmodulin inhibition of E2A strongly enhances this UNG2 accumulation, indicating that it is negatively regulated by E2A as well. We show also that over-expression of E2A can suppress class switch recombination. The results suggest that E2A is a key factor in regulating the balance between AID and UNG2, both at expression and Ig targeting levels, to stimulate Ig diversification and suppress normal DNA repair processes. (c) 2014 Elsevier Ltd. All rights reserved.

Keywords
B cells, Cell differentiation, Antibodies, Gene regulation, Transcription factors
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-90404 (URN)10.1016/j.molimm.2014.03.011 (DOI)000336473200004 ()
Available from: 2014-07-10 Created: 2014-06-23 Last updated: 2018-06-07Bibliographically approved
Hauser, J., Kumar, R., Wallenius, A., Grundström, C., Ahmed, T. & Grundström, T. (2014). Regulation of diversification and affinity maturation of antibodies. International Journal of Molecular Medicine, 34, S50-S50
Open this publication in new window or tab >>Regulation of diversification and affinity maturation of antibodies
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2014 (English)In: International Journal of Molecular Medicine, ISSN 1107-3756, E-ISSN 1791-244X, Vol. 34, p. S50-S50Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Spandidos publishing, 2014
National Category
Basic Medicine
Identifiers
urn:nbn:se:umu:diva-94174 (URN)000341276000184 ()
Note

Supplement 1, Meeting abstract 283

Available from: 2014-10-06 Created: 2014-10-06 Last updated: 2018-06-07Bibliographically approved
Hauser, J., Verma-Gaur, J. & Grundström, T. (2013). Broad feedback inhibition of pre-B-cell receptor signaling components. Molecular Immunology, 54(3-4), 247-253
Open this publication in new window or tab >>Broad feedback inhibition of pre-B-cell receptor signaling components
2013 (English)In: Molecular Immunology, ISSN 0161-5890, E-ISSN 1872-9142, Vol. 54, no 3-4, p. 247-253Article in journal (Refereed) Published
Abstract [en]

During B lymphocyte development, first immunoglobulin heavy chain gene segments and then immunoglobulin light chain gene segments are rearranged to create antibody diversity. Early in the development, expression of a pre-B-cell receptor (pre-BCR) that has membrane-bound Ig heavy chain protein associated with surrogate light chain (SLC) proteins serves as a critical checkpoint that monitors for functional heavy chain rearrangement. Signaling from the pre-BCR induces survival and clonal expansion to select cells with good heavy chains, but it also down-regulates transcription of the genes for the SLC proteins and CD19 and limits its own proliferative signaling. Here we have analyzed whether the down-regulation is limited to the SLC proteins and CD19, and we show that the pre-BCR of primary mouse pre-B-cells instead is subject to a broad feedback inhibition of pre-BCR signaling components. Activation of signaling leads to down-regulation of the receptor proteins, many co-receptors and proteins participating in signal pathways from the receptor. Thus the down-regulation of the pre-BCR is much broader than previously assumed. We also show that Ca2+/calmodulin inhibition of the transcription factor E2A is required for the feedback inhibition of the pre-BCR signaling proteins. (C) 2012 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2013
Keywords
Pre-BCR, Calcium signaling, Cell proliferation, Gene regulation, E2A, Calmodulin, Signal transduction
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-70330 (URN)10.1016/j.molimm.2012.12.002 (DOI)000317157000001 ()
Available from: 2013-05-14 Created: 2013-05-14 Last updated: 2018-06-08Bibliographically approved
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