Somatic hypermutation and B-cell malignancies

Spencer, Jo; Dunn-Walters, Deborah K.

doi:10.1002/(sici)1096-9896(199901)187:2<158::aid-path226>3.0.co;2-6

Cited by 23 publications

(10 citation statements)

References 50 publications

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“…Because pol error specificity does not correlate with substitutions in the RGYW sequence motif, and because those substitutions are distributed equally on both strands, we further suggested that SHM may involve more than one DNA transaction and more than one DNA polymerase (8). This finding is consistent with the two-phase model of SHM proposed earlier (9,13). Other DNA polymerases suggested to participate in SHM include pol (14)(15)(16), pol (17,18) and pol (19).…”

supporting

confidence: 83%

“…Although the mechanism for introducing these sequence changes is currently unknown, several features of SHM specificity offer clues to the DNA transactions that might be involved. For example, SHM primarily occurs in two highly mutable DNA sequence motifs (5)(6)(7)(8)(9). One is the RGYW sequence (the underlined G is mutated, R ϭ A or G, Y ϭ T or C, and W ϭ A or T), which is found in SHM substitution spectra in equal proportions in both DNA strands.…”

mentioning

confidence: 99%

“…One is the RGYW sequence (the underlined G is mutated, R ϭ A or G, Y ϭ T or C, and W ϭ A or T), which is found in SHM substitution spectra in equal proportions in both DNA strands. The other is the WA motif, where substitutions are more likely in one strand than the other (5,(7)(8)(9)(10). A clue to the origins of the substitutions in the WA motif is the observation that their type and location correlates with the base substitution error specificity of human DNA polymerase when copying a bacterial gene sequence in a model system in vitro (8).…”

mentioning

confidence: 99%

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Correlation of somatic hypermutation specificity and A-T base pair substitution errors by DNA polymerase η during copying of a mouse immunoglobulin κ light chain transgene

Pavlov

Rogozin

Galkin

et al. 2002

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

118

110

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To test the hypothesis that inaccurate DNA synthesis by mammalian DNA polymerase (pol ) contributes to somatic hypermutation (SHM) of Ig genes, we measured the error specificity of mouse pol during synthesis of each strand of a mouse Ig light chain transgene. We then compared the results to the base substitution specificity of SHM of this same gene in the mouse. The in vitro and in vivo base substitution spectra shared a number of common features. A highly significant correlation was observed for overall substitutions at A-T pairs but not for substitutions at G-C pairs. Sixteen mutational hotspots at A-T pairs observed in vivo were also found in spectra generated by mouse pol in vitro. The correlation was strongest for errors made by pol during synthesis of the non-transcribed strand, but it was also observed for synthesis of the transcribed strand. These facts, and the distribution of substitutions generated in vivo, support the hypothesis that pol contributes to SHM of Ig genes at A-T pairs via short patches of low fidelity DNA synthesis of both strands, but with a preference for the non-transcribed strand.H igh affinity antibodies result from somatic hypermutation (SHM) of Ig genes followed by selection. The SHM process introduces base substitutions at a very high rate into DNA encoding the variable regions of immunoglobulins (1-4). Although the mechanism for introducing these sequence changes is currently unknown, several features of SHM specificity offer clues to the DNA transactions that might be involved. For example, SHM primarily occurs in two highly mutable DNA sequence motifs (5-9). One is the RGYW sequence (the underlined G is mutated, R ϭ A or G, Y ϭ T or C, and W ϭ A or T), which is found in SHM substitution spectra in equal proportions in both DNA strands. The other is the WA motif, where substitutions are more likely in one strand than the other (5, 7-10). A clue to the origins of the substitutions in the WA motif is the observation that their type and location correlates with the base substitution error specificity of human DNA polymerase when copying a bacterial gene sequence in a model system in vitro (8). Based on that correlation and additional considerations of the two mutable motifs (11), we suggested that errors at A-T base pairs by pol may contribute to as much as one third of somatic mutations in Ig genes, preferentially during synthesis of the non-transcribed strand. This hypothesis is supported by the observation that XP-V patients lacking active polymerase have a lower proportion of somatic substitutions at A-T base pairs in Ig genes (12). Because pol error specificity does not correlate with substitutions in the RGYW sequence motif, and because those substitutions are distributed equally on both strands, we further suggested that SHM may involve more than one DNA transaction and more than one DNA polymerase (8). This finding is consistent with the two-phase model of SHM proposed earlier (9, 13). Other DNA polymerases suggested to participate in SHM include pol (14-16), pol (17, 18) ...

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supporting

confidence: 83%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Correlation of somatic hypermutation specificity and A-T base pair substitution errors by DNA polymerase η during copying of a mouse immunoglobulin κ light chain transgene

Pavlov

Rogozin

Galkin

et al. 2002

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

118

110

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“…The majority of our gastric MALT lymphomas showed somatic mutation, which is consistent with a derivation from postgerminal center memory B cells. 33,34 In conclusion, we showed that inflammationdependent gastric MALT lymphomas frequently used particular VH fragments and that this usage was not found in inflammation-independent tumors. This finding suggests that the former tumors may be derived from a highly restricted, probably H. pyloriassociated, B cell subset and that tumor progression from the former to the latter may not commonly occur.…”

Section: Discussionmentioning

confidence: 64%

Immunoglobulin VH gene analysis in gastric MALT lymphomas

et al. 2007

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The majority of gastric mucosa-associated lymphoid tissue (MALT) lymphomas are successfully treated with Helicobacter pylori eradication alone. However, certain subsets of these tumors are resistant to the eradication treatment. As API2-MALT1 fusion is a feature of one of these subsets, we divided gastric MALT lymphomas into three groups: eradication-responsive and API2-MALT1 fusion-negative (Group A), eradication-resistant and fusion-negative (Group B), and eradication-resistant and fusion-positive (Group C). To characterize further gastric MALT lymphomas, we analyzed VH genes, which do not change in the course of tumor progression, by extensive subcloning of the monoclonal PCR products of 45 cases. VH3-23 and VH3-30 were preferentially used in Group A tumors (14/23 cases, 61%) as compared with Group B (1/10 cases, 10%, P ¼ 0.0094) and Group C (2/ 12 cases, 17%, P ¼ 0.017). Tumors of Groups B and C used variegated VH fragments, and no dominant VH fragments were noted. Somatic mutation was detected in most of the cases. Ongoing mutation was detected in 3/45 cases (7%), when assessed according to strict criteria for a confirmed mutation. These findings suggest that inflammation-dependent tumors (Group A) may be derived from a highly restricted, probably H. pyloriassociated, B cell subset and may not often progress to those that are inflammation-independent (Groups B and C). Although considered to be common in this tumor, ongoing mutation may be infrequent when assessed by strict criteria. Keywords: gastric MALT lymphoma; helicobacter pylori; eradication; immunoglobulin heavy chain variable genes; API2-MALT1 fusion gene Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) is a distinct low-grade lymphoma, which is typically localized long term at the site of origin. 1 A preexisting chronic inflammation, such as Helicobacter pylori gastritis, Hashimoto's thyroiditis, or Sjogren's syndrome is considered to influence significantly its development. 1 The etiological link between gastric MALT lymphoma and H. pylori gastritis has arisen from the fact that the majority of gastric MALT lymphomas (approximately 70% of cases) show complete regression on eradication of H. pylori alone. 2 API2-MALT1 fusion, cloned from t(11;18)(q21;q21), is a gene alteration specific to MALT lymphomas. 3,4 API2 is a member of the IAP (inhibitor of apoptosis) gene family, and is essential for the suppression of apoptosis. 5 MALT1, a novel

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“…When comparing J-C isotype usage in normal PB B cells (Ignatovitch et al) and SmIg + malignant B cells, there is a significant shift from J-C 1 (27% vs 12%) to J-C 3 (34% vs 31,32 Therefore, it is unlikely that receptor editing induced by unfavorable somatic mutations is the sole explanation for the observed significant difference in J-C usage.…”

Section: Leukemiamentioning

confidence: 99%