Generation of antibody diversity in the immune response of BALB/c mice to influenza virus hemagglutinin.

McKean, David J.; Hüppi, Konrad; Bell, Michael V.; Staudt, Louis M.; Gerhard, Walter; Weigert, Martin

doi:10.1073/pnas.81.10.3180

Cited by 472 publications

(318 citation statements)

References 24 publications

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“…However, these were purely correlations, and it is difficult to imagine how an AID-induced mutation at one dC in the V region would influence the frequency of mutations at distant dCs, as it appears that most of the time there is only one AID-induced mutation during each cell cycle (53)(54)(55). This raised the alternative possibility that the results described in Figs.…”

Section: Association Of Mutations In the Ohs1 And Ohs2 With Mutationsmentioning

confidence: 50%

Overlapping hotspots in CDRs are critical sites for V region diversification

Wei

Chahwan

Wang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Activation-induced deaminase (AID) mediates the somatic hypermutation (SHM) of Ig variable (V) regions that is required for the affinity maturation of the antibody response. An intensive analysis of a published database of somatic hypermutations that arose in the IGHV3-23*01 human V region expressed in vivo by human memory B cells revealed that the focus of mutations in complementary determining region (CDR)1 and CDR2 coincided with a combination of overlapping AGCT hotspots, the absence of AID cold spots, and an abundance of polymerase eta hotspots. If the overlapping hotspots in the CDR1 or CDR2 did not undergo mutation, the frequency of mutations throughout the V region was reduced. To model this result, we examined the mutation of the human IGHV3-23*01 biochemically and in the endogenous heavy chain locus of Ramos B cells. Deep sequencing revealed that IGHV3-23*01 in Ramos cells accumulates AID-induced mutations primarily in the AGCT in CDR2, which was also the most frequent site of mutation in vivo. Replacing the overlapping hotspots in CDR1 and CDR2 with neutral or cold motifs resulted in a reduction in mutations within the modified motifs and, to some degree, throughout the V region. In addition, some of the overlapping hotspots in the CDRs were at sites in which replacement mutations could change the structure of the CDR loops. Our analysis suggests that the local sequence environment of the V region, and especially of the CDR1 and CDR2, is highly evolved to recruit mutations to key residues in the CDRs of the IgV region.A fter an encounter with antigen and subsequent migration into the germinal centers of the secondary lymphoid organs, B cells undergo a regulated cascade of mutational events that occur at a very high frequency and are largely restricted to the variable (V) and switch (S) regions of the Ig heavy chain locus and the V region of the light chain locus. These mutagenic events are responsible for the somatic hypermutation (SHM) of the V regions and the class switch recombination of the constant (C) regions that are required for protective antibodies (1, 2). Both SHM and class switch recombination are initiated by activationinduced deaminase (AID) that preferentially deaminates the dC residues in WRC (W = A/T, R = A/G) hotspot motifs at frequencies 2-10-fold higher than SYC (S = G/C; Y = C/T) cold spots (3-7). During V region SHM, the resulting dU:G mismatch can then be replicated during S-phase to produce transition mutations, be processed by uracil-DNA glycosylase 2 and apurinic/ apyrimidinic endonucleases through the base excision repair pathway to produce both transitions and transversions (8-10), or be recognized by MutS homolog (MSH)2/MSH6 of the mismatch repair (MMR) complex that recruits the low-fidelity polymerase eta (Polη) to generate additional mutations at neighboring A:T residues (11).The specificity of AID targeting to the Ig gene has been under intense investigation. Studies have shown that AID deamination and mutagenesis targets single-stranded DNA substrates generated during ...

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Section: Association Of Mutations In the Ohs1 And Ohs2 With Mutationsmentioning

confidence: 50%

Overlapping hotspots in CDRs are critical sites for V region diversification

Wei

Chahwan

Wang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Since the frequency of somatic mutations in CA, (0.31%) was less than 1/10th of that in VAl-JAl (3.32%), it was difficult to detect nucleotide changes in the CA, gene when the total number of somatic mutations was low as in the S43 Al-chain. Although the frequency of mutation in CAl was low, it was higher than the basal mutation frequency (11,(36)(37)(38). Therefore, the somatic mutator mechanism was definitely active in the CAl exon.…”

Section: Somatic Mutation Of Rearranged Unexpressed V-ja2mentioning

confidence: 95%

Somatic mutation in constant regions of mouse lambda 1 light chains.

Motoyama

Okada

Azuma

1991

Proc. Natl. Acad. Sci. U.S.A.

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To study the distribution of somatic mutation, we determined nucleotide sequences of rearranged Alchain genomic DNA from four hybridomas obtained from C57BL/6 mice that had been immunized with (4-hydroxy-3-nitrophenyl)acetyl-conjugated chicken gamma globulin. In total, 114 nucleotide substitutions were observed, with neither insertion nor deletion. Sixty-one mutations occurred in the variable-joining region genes (VAI-JA1) and 49 in joiningconstant (JAI-CAl) introns. Although frequency decreased with distance from the VAI-JAl coding region, somatic mutations occurred in the entire JAI-CAI intron and even in the CAI region. We found four nucleotide substitutions in CA, genes, all of which were replacement mutations. Therefore, the mechanism responsible for somatic mutation is operative into the CA, exons. Nucleotide sequences of rearranged but inactive A2-chain genes from two hybridomas were also examined and compared with those of Al-chain genes. The clustering of replacement mutations in complementarity-determining regions in the inactive A2-chain genes similar to the active Al-chain genes suggested a mechanism that induces somatic mutation preferentially in this region even in the absence of antigenic selection.Sequence diversity in the variable (V) domains of immunoglobulins is generated by random recombination of V, diversity (D), and joining (J) gene segments of heavy (H) chains or V and J segments of light (L) chains (1). Insertion of the N region and flexibility in the recombination sites also result in the variation in the V domain sequences (2). Somatic mutation introduces additional variation to VH and VL domains (1, 3-6). It has been shown that somatic mutation is triggered by stimulation with thymus-dependent antigens (3, 4, 6, 7) and is found in rearranged immunoglobulin genes both active and inactive (8)(9)(10)(11)(12). The somatic mutation mechanism is as yet unclear, although several models have been proposed (13-15). To evaluate possible mechanisms, information on the distribution of somatic mutations is undoubtedly required (5,(16)(17)(18)(19). Both murine and human immunoglobulin gene sequences show a lack of somatic mutation in the constant (C) region exons of H and K chains (5,17,20,21). However, Cleary et al. (22) reported the occurrence of somatic mutation in the human CA exon. Because of the complex genetics and gene structure of human immunoglobulins, it is rather difficult to distinguish between nucleotide variations arising from somatic mutation and those from other mechanisms.Murine A chains are particularly useful for examining the distribution of somatic mutations because of their simple gene structures (23-25). The A-chain genes possess only two VL genes (VA1 and VA2), which recombine with JA1, JA2, orJA3.Selective recombination of VA, to JA1CA1 or JA3-CA3 has been commonly observed (26,27). Therefore, a variation in sequence as a result of somatic mutation could be easily distinguished from that generated by other mechanisms.Furthermore, the J-C introns of A-chain genes di...

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“…The molecular basis of this process was first unveiled by the analysis of the binding affinity and primary structure of monoclonal antibodies (mAbs) generated at successive stages of murine immune responses to different conjugated haptens and antigens [2][3][4][5][6][7][8][9][10] . The first exposure to antigen results in recruitment of B-cell clonotypes that bind antigen by virtue of the combinatorial and junctional specificity of their unmutated surface receptors (Ig V segments).…”

mentioning

confidence: 99%

The CDR1 sequences of a major proportion of human germline Ig VH genes are inherently susceptible to amino acid replacement

1994

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The variable (V) genes of antigen-selected antibodies are known to exhibit a higher frequency of amino acid replacement mutations in the sequences encoding the antigen-contacting complementarity-determining regions (CDRs) than in those encoding the 'structural' framework regions (FRs). Here, Bernard Chang and Paolo Casali analyse the impact of regional differences in the codon composition of human germline Ig V H and V L genes on regional differences in the frequency of replacement mutations in the gene products (i.e. the antigen-binding sites of antibody molecules). This analysis reveals that CDR and FR sequences can differ significantly in their inherent susceptibility to amino acid replacement given any single nucleotide change. Thus, the CDR sequences of all the Ig V H genes analysed comprise a higher frequency of codons susceptible to replacement mutations than would be expected for a random sequence. Conversely, the FR sequences comprise codons less susceptible to replacement mutations than expected. Random accumulation of nucleotide changes throughout the coding sequence of an Ig V-gene segment containing CDRs inherently more prone to replacement mutations than the respective FRs would inevitably yield a higher rate of amino acid replacements in the CDRs than in the FRs. This would provide a fertile structural substrate of hypervariability for antigen selection while still maintaining the structural integrity of the FRs.The production of antibodies with progressively higher affinity for antigen is an important feature of B-cell clonotypes recruited by repeated antigenic challenge, and is referred to as affinity maturation 1 . The molecular basis of this process was first unveiled by the analysis of the binding affinity and primary structure of monoclonal antibodies (mAbs) generated at successive stages of murine immune responses to different conjugated haptens and antigens [2][3][4][5][6][7][8][9][10] . The first exposure to antigen results in recruitment of B-cell clonotypes that bind antigen by virtue of the combinatorial and junctional specificity of their unmutated surface receptors (Ig V segments). Subsequent exposures to antigen lead to accumulation of somatic point mutations in the antibody V segments and antigen selection of the highaffinity mutated B-cell clonotypes. Sequential rounds of mutation and selection eventually result in restriction of the response to those B cells with the best 'fit' for antigen 11,12 . Somatic point mutations in Ig V-gene segmentsIn the absence of negative or positive selective pressure on the gene product, a random mutational process would entail an even distribution of nucleotide changes yielding amino HHS Public Access Author ManuscriptAuthor Manuscript Author ManuscriptAuthor Manuscript acid replacements (R mutations) and nucleotide changes not yielding amino acid replacements (S, or silent, mutations) throughout the coding sequence. However, antigenselected antibodies have been shown to include a higher frequency of R mutations in the Ig V-gene complemen...

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Generation of antibody diversity in the immune response of BALB/c mice to influenza virus hemagglutinin.

Cited by 472 publications

References 24 publications

Overlapping hotspots in CDRs are critical sites for V region diversification

Overlapping hotspots in CDRs are critical sites for V region diversification

Somatic mutation in constant regions of mouse lambda 1 light chains.

The CDR1 sequences of a major proportion of human germline Ig VH genes are inherently susceptible to amino acid replacement

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