scholarly journals DNA polymerase β is able to repair breaks in switch regions and plays an inhibitory role during immunoglobulin class switch recombination

2007 ◽  
Vol 204 (7) ◽  
pp. 1677-1689 ◽  
Author(s):  
Xiaoming Wu ◽  
Janet Stavnezer
Keyword(s):  
B Cells ◽  
Dna Polymerase ◽  
Excision Repair ◽  
Cytidine Deaminase ◽  
Class Switch Recombination ◽  
Strand Break ◽  
Dna Polymerase Β ◽  
Single Strand Break ◽  
Class Switch ◽  
Base Excision

Immunoglobulin (Ig) class switch recombination (CSR) is initiated by activation-induced cytidine deaminase (AID), which converts cytosines to uracils in switch (S) regions. Subsequent excision of dU by uracil DNA glycosylase (UNG) of the base excision repair (BER) pathway is required to obtain double-strand break (DSB) intermediates for CSR. Since UNG normally initiates faithful repair, it is unclear how the AID-instigated S region lesions are converted into DSBs rather than correctly repaired by BER. Normally, DNA polymerase β (Polβ) would replace the dC deaminated by AID, leading to correct repair of the single-strand break, thereby preventing CSR. We address the question of whether Polβ might be specifically down-regulated during CSR or inhibited from accessing the AID-instigated lesions, or whether the numerous AID-initiated S region lesions might simply overwhelm the BER capacity. We find that nuclear Polβ levels are induced upon activation of splenic B cells to undergo CSR. When Polβ−/− B cells are activated to switch in culture, they switch slightly better to IgG2a, IgG2b, and IgG3 and have more S region DSBs and mutations than wild-type controls. We conclude that Polβ attempts to faithfully repair S region lesions but fails to repair them all.

scholarly journals DNA polymerase β prevents AID-instigated mutagenic non-canonical mismatch DNA repair

2020 ◽  
Author(s):  
Mahnoush Bahjat ◽  
Maria Stratigopoulou ◽  
Bas Pilzecker ◽  
Tijmen P. van Dam ◽  
Simon Mobach ◽  
...  
Keyword(s):  
B Cells ◽  
Dna Polymerase ◽  
Somatic Hypermutation ◽  
Excision Repair ◽  
Clonal Selection ◽  
Cytidine Deaminase ◽  
Affinity Maturation ◽  
Dna Polymerase Β ◽  
Immunoglobulin Variable Genes ◽  
Base Excision

ABSTRACTIn B cells, the error-prone repair of activation-induced cytidine deaminase (AID)-induced lesions in immunoglobulin variable genes cause somatic hypermutation (SHM) of antibody genes. Due to clonal selection in the germinal centers (GC) this active mutation process provides the molecular basis for antibody affinity maturation. AID deaminates cytosine (C) to create uracil (U) in DNA. Typically, the short patch base excision repair (spBER) effectively restores genomic U lesions. We here demonstrate that GC B cells actively degrade DNA polymerase β (Polβ), resulting in the inactivation of the gap-filling step of spBER. Consequently, lesions instigated by AID, and likely other base damages, are channeled towards mutagenic non-canonical mismatch repair (mncMMR), responsible for the vast majority of mutations at adenine and thymine (A:T) bases. Apparently, GC B cells prohibit faithful spBER, thereby favoring A:T mutagenesis during SHM. Lastly, our data suggest that the loss of Polβ relates to hypoxia that characterizes the GC microenvironment.

scholarly journals MBD4 Facilitates Immunoglobulin Class Switch Recombination

2016 ◽  
Vol 37 (2) ◽  
Author(s):  
Fernando Grigera ◽  
Robert Wuerffel ◽  
Amy L. Kenter
Keyword(s):  
Excision Repair ◽  
Cytidine Deaminase ◽  
Ectopic Expression ◽  
Class Switch Recombination ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Class Switch ◽  
Activation Induced Cytidine Deaminase ◽  
Base Excision

ABSTRACT Immunoglobulin heavy chain class switch recombination (CSR) requires targeted formation of DNA double-strand breaks (DSBs) in repetitive switch region elements followed by ligation between distal breaks. The introduction of DSBs is initiated by activation-induced cytidine deaminase (AID) and requires base excision repair (BER) and mismatch repair (MMR). The BER enzyme methyl-CpG binding domain protein 4 (MBD4) has been linked to the MMR pathway through its interaction with MutL homologue 1 (MLH1). We find that when Mbd4 exons 6 to 8 are deleted in a switching B cell line, DSB formation is severely reduced and CSR frequency is impaired. Impaired CSR can be rescued by ectopic expression of Mbd4. Mbd4 deficiency yields a deficit in DNA end processing similar to that found in MutS homologue 2 (Msh2)- and Mlh1-deficient B cells. We demonstrate that microhomology-rich S-S junctions are enriched in cells in which Mbd4 is deleted. Our studies suggest that Mbd4 is a component of MMR-directed DNA end processing.

scholarly journals The human checkpoint sensor and alternative DNA clamp Rad9–Rad1–Hus1 modulates the activity of DNA ligase I, a component of the long-patch base excision repair machinery

2005 ◽  
Vol 389 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Ekaterina SMIRNOVA ◽  
Magali TOUEILLE ◽  
Enni MARKKANEN ◽  
Ulrich HÜBSCHER
Keyword(s):  
Quality Control ◽  
Dna Polymerase ◽  
Base Excision Repair ◽  
Excision Repair ◽  
Dna Ligase ◽  
Dna Polymerase Β ◽  
Flap Endonuclease 1 ◽  
Important Target ◽  
Dna Ligase I ◽  
Base Excision

The human checkpoint sensor and alternative clamp Rad9–Rad1–Hus1 can interact with and specifically stimulate DNA ligase I. The very recently described interactions of Rad9–Rad1–Hus1 with MutY DNA glycosylase, DNA polymerase β and Flap endonuclease 1 now complete our view that the long-patch base excision machinery is an important target of the Rad9–Rad1–Hus1 complex, thus enhancing the quality control of DNA.

scholarly journals DNA polymerase β outperforms DNA polymerase γ in key mitochondrial base excision repair activities

DNA Repair ◽  
2021 ◽  
Vol 99 ◽  
pp. 103050
Author(s):  
Beverly A. Baptiste ◽  
Stephanie L. Baringer ◽  
Tomasz Kulikowicz ◽  
Joshua A. Sommers ◽  
Deborah L. Croteau ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Base Excision Repair ◽  
Excision Repair ◽  
Dna Polymerase Β ◽  
Base Excision ◽  
Dna Polymerase Γ

scholarly journals Base excision repair and design of small molecule inhibitors of human DNA polymerase β

2010 ◽  
Vol 67 (21) ◽  
pp. 3633-3647 ◽  
Author(s):  
Samuel H. Wilson ◽  
William A. Beard ◽  
David D. Shock ◽  
Vinod K. Batra ◽  
Nisha A. Cavanaugh ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Small Molecule ◽  
Base Excision Repair ◽  
Small Molecule Inhibitors ◽  
Excision Repair ◽  
Dna Polymerase Β ◽  
Human Dna ◽  
Base Excision

DNA Polymerase β Promotes Recruitment of DNA Ligase IIIα−XRCC1 to Sites of Base Excision Repair

Biochemistry ◽  
2005 ◽  
Vol 44 (31) ◽  
pp. 10613-10619 ◽  
Author(s):  
Jason L. Parsons ◽  
Irina I. Dianova ◽  
Sarah L. Allinson ◽  
Grigory L. Dianov
Keyword(s):  
Dna Polymerase ◽  
Base Excision Repair ◽  
Excision Repair ◽  
Dna Ligase ◽  
Dna Polymerase Β ◽  
Base Excision

scholarly journals A novel regulatory circuit in base excision repair involving AP endonuclease 1, Creb1 and DNA polymerase β

2010 ◽  
Vol 39 (8) ◽  
pp. 3156-3165 ◽  
Author(s):  
De-Sheng Pei ◽  
Xiao-Jie Yang ◽  
Wei Liu ◽  
Jeroen E. J. Guikema ◽  
Carol E. Schrader ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Base Excision Repair ◽  
Excision Repair ◽  
Dna Polymerase Β ◽  
Ap Endonuclease ◽  
Regulatory Circuit ◽  
Ap Endonuclease 1 ◽  
Base Excision

scholarly journals MSH2–MSH6 stimulates DNA polymerase η, suggesting a role for A:T mutations in antibody genes

2005 ◽  
Vol 201 (4) ◽  
pp. 637-645 ◽  
Author(s):  
Teresa M. Wilson ◽  
Alexandra Vaisman ◽  
Stella A. Martomo ◽  
Patsa Sullivan ◽  
Li Lan ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Base Excision Repair ◽  
Somatic Hypermutation ◽  
Excision Repair ◽  
Cytidine Deaminase ◽  
Abasic Site ◽  
Cell Extracts ◽  
Activation Induced Cytidine Deaminase ◽  
Base Excision

Activation-induced cytidine deaminase deaminates cytosine to uracil (dU) in DNA, which leads to mutations at C:G basepairs in immunoglobulin genes during somatic hypermutation. The mechanism that generates mutations at A:T basepairs, however, remains unclear. It appears to require the MSH2–MSH6 mismatch repair heterodimer and DNA polymerase (pol) η, as mutations of A:T are decreased in mice and humans lacking these proteins. Here, we demonstrate that these proteins interact physically and functionally. First, we show that MSH2–MSH6 binds to a U:G mismatch but not to other DNA intermediates produced during base excision repair of dUs, including an abasic site and a deoxyribose phosphate group. Second, MSH2 binds to pol η in solution, and endogenous MSH2 associates with the pol in cell extracts. Third, MSH2–MSH6 stimulates the catalytic activity of pol η in vitro. These observations suggest that the interaction between MSH2–MSH6 and DNA pol η stimulates synthesis of mutations at bases located downstream of the initial dU lesion, including A:T pairs.

scholarly journals DNA Polymerase η Is Involved in Hypermutation Occurring during Immunoglobulin Class Switch Recombination

2004 ◽  
Vol 199 (2) ◽  
pp. 265-270 ◽  
Author(s):  
Ahmad Faili ◽  
Said Aoufouchi ◽  
Sandra Weller ◽  
Françoise Vuillier ◽  
Anne Stary ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Dna Sequences ◽  
Tandem Repeats ◽  
Somatic Hypermutation ◽  
Cytidine Deaminase ◽  
Class Switch Recombination ◽  
Class Switch ◽  
Mutation Pattern ◽  
Immunoglobulin Locus ◽  
V Gene

Base substitutions, deletions, and duplications are observed at the immunoglobulin locus in DNA sequences involved in class switch recombination (CSR). These mutations are dependent upon activation-induced cytidine deaminase (AID) and present all the characteristics of the ones observed during V gene somatic hypermutation, implying that they could be generated by the same mutational complex. It has been proposed, based on the V gene mutation pattern of patients with the cancer-prone xeroderma pigmentosum variant (XP-V) syndrome who are deficient in DNA polymerase η (pol η), that this enzyme could be responsible for a large part of the mutations occurring on A/T bases. Here we show, by analyzing switched memory B cells from two XP-V patients, that pol η is also an A/T mutator during CSR, in both the switch region of tandem repeats as well as upstream of it, thus suggesting that the same error-prone translesional polymerases are involved, together with AID, in both processes.

scholarly journals Protection against Methylation-induced Cytotoxicity by DNA Polymerase β-Dependent Long Patch Base Excision Repair

2000 ◽  
Vol 275 (3) ◽  
pp. 2211-2218 ◽  
Author(s):  
Julie K. Horton ◽  
Rajendra Prasad ◽  
Esther Hou ◽  
Samuel H. Wilson
Keyword(s):  
Dna Polymerase ◽  
Base Excision Repair ◽  
Excision Repair ◽  
Dna Polymerase Β ◽  
Base Excision
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