Chicken MBD4 Regulates Immunoglobulin Diversification by Somatic Hypermutation
Immunoglobulin (Ig) diversification occurs via somatic hypermutation (SHM) and class switch recombination (CSR), and is initiated by activation-induced deaminase (AID), which converts cytosine to uracil. Variable (V) region genes undergo SHM to create amino acid substitutions that produce antibodies...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2019-11-01
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| Series: | Frontiers in Immunology |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fimmu.2019.02540/full |
| _version_ | 1819238791648378880 |
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| author | Ryan Costello Jose F. Cantillo Amy L. Kenter |
| author_facet | Ryan Costello Jose F. Cantillo Amy L. Kenter |
| author_sort | Ryan Costello |
| collection | DOAJ |
| description | Immunoglobulin (Ig) diversification occurs via somatic hypermutation (SHM) and class switch recombination (CSR), and is initiated by activation-induced deaminase (AID), which converts cytosine to uracil. Variable (V) region genes undergo SHM to create amino acid substitutions that produce antibodies with higher affinity for antigen. The conversion of cytosine to uracil in DNA promotes mutagenesis. Two distinct DNA repair mechanisms regulate uracil processing in Ig genes. The first involves base removal by the uracil DNA glycosylase (UNG), and the second detects uracil via the mismatch repair (MMR) complex. Methyl binding domain protein 4 (MBD4) is a uracil glycosylase and an intriguing candidate for involvement in somatic hypermutation because of its interaction with the MMR MutL homolog 1 (MLH1). We found that the DNA uracil glycosylase domain of MBD4 is highly conserved among mammals, birds, shark, and insects. Conservation of the human and chicken MBD4 uracil glycosylase domain structure is striking. Here we examined the function of MBD4 in chicken DT40 B cells which undergo constitutive SHM. We constructed structural variants of MBD4 DT40 cells using CRISPR/Cas9 genome editing. Disruption of the MBD4 uracil glycosylase catalytic region increased SHM frequency in IgM loss assays. We propose that MBD4 plays a role in SHM. |
| first_indexed | 2024-12-23T13:41:50Z |
| format | Article |
| id | doaj.art-b695136a73834e23a83b585de347f932 |
| institution | Directory Open Access Journal |
| issn | 1664-3224 |
| language | English |
| last_indexed | 2024-12-23T13:41:50Z |
| publishDate | 2019-11-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Immunology |
| spelling | doaj.art-b695136a73834e23a83b585de347f9322022-12-21T17:44:50ZengFrontiers Media S.A.Frontiers in Immunology1664-32242019-11-011010.3389/fimmu.2019.02540479520Chicken MBD4 Regulates Immunoglobulin Diversification by Somatic HypermutationRyan CostelloJose F. CantilloAmy L. KenterImmunoglobulin (Ig) diversification occurs via somatic hypermutation (SHM) and class switch recombination (CSR), and is initiated by activation-induced deaminase (AID), which converts cytosine to uracil. Variable (V) region genes undergo SHM to create amino acid substitutions that produce antibodies with higher affinity for antigen. The conversion of cytosine to uracil in DNA promotes mutagenesis. Two distinct DNA repair mechanisms regulate uracil processing in Ig genes. The first involves base removal by the uracil DNA glycosylase (UNG), and the second detects uracil via the mismatch repair (MMR) complex. Methyl binding domain protein 4 (MBD4) is a uracil glycosylase and an intriguing candidate for involvement in somatic hypermutation because of its interaction with the MMR MutL homolog 1 (MLH1). We found that the DNA uracil glycosylase domain of MBD4 is highly conserved among mammals, birds, shark, and insects. Conservation of the human and chicken MBD4 uracil glycosylase domain structure is striking. Here we examined the function of MBD4 in chicken DT40 B cells which undergo constitutive SHM. We constructed structural variants of MBD4 DT40 cells using CRISPR/Cas9 genome editing. Disruption of the MBD4 uracil glycosylase catalytic region increased SHM frequency in IgM loss assays. We propose that MBD4 plays a role in SHM.https://www.frontiersin.org/article/10.3389/fimmu.2019.02540/fullIgsomatic hypermutationB cellsuracil DNA glycosylaseDT40CRISPR |
| spellingShingle | Ryan Costello Jose F. Cantillo Amy L. Kenter Chicken MBD4 Regulates Immunoglobulin Diversification by Somatic Hypermutation Frontiers in Immunology Ig somatic hypermutation B cells uracil DNA glycosylase DT40 CRISPR |
| title | Chicken MBD4 Regulates Immunoglobulin Diversification by Somatic Hypermutation |
| title_full | Chicken MBD4 Regulates Immunoglobulin Diversification by Somatic Hypermutation |
| title_fullStr | Chicken MBD4 Regulates Immunoglobulin Diversification by Somatic Hypermutation |
| title_full_unstemmed | Chicken MBD4 Regulates Immunoglobulin Diversification by Somatic Hypermutation |
| title_short | Chicken MBD4 Regulates Immunoglobulin Diversification by Somatic Hypermutation |
| title_sort | chicken mbd4 regulates immunoglobulin diversification by somatic hypermutation |
| topic | Ig somatic hypermutation B cells uracil DNA glycosylase DT40 CRISPR |
| url | https://www.frontiersin.org/article/10.3389/fimmu.2019.02540/full |
| work_keys_str_mv | AT ryancostello chickenmbd4regulatesimmunoglobulindiversificationbysomatichypermutation AT josefcantillo chickenmbd4regulatesimmunoglobulindiversificationbysomatichypermutation AT amylkenter chickenmbd4regulatesimmunoglobulindiversificationbysomatichypermutation |