Histone H3.3 promotes IgV gene diversification by enhancing formation of AID‐accessible single‐stranded DNA

Immunoglobulin diversification is driven by activation‐induced deaminase (AID), which converts cytidine to uracil within the Ig variable (IgV) regions. Central to the recruitment of AID to the IgV genes are factors that regulate the generation of single‐stranded DNA (ssDNA), the enzymatic substrate...

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Autores principales: Romanello, Marina, Schiavone, Davide, Frey, Alexander, Sale, Julian E
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4883027/
https://www.ncbi.nlm.nih.gov/pubmed/27220848
http://dx.doi.org/10.15252/embj.201693958
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author Romanello, Marina
Schiavone, Davide
Frey, Alexander
Sale, Julian E
author_facet Romanello, Marina
Schiavone, Davide
Frey, Alexander
Sale, Julian E
author_sort Romanello, Marina
collection PubMed
description Immunoglobulin diversification is driven by activation‐induced deaminase (AID), which converts cytidine to uracil within the Ig variable (IgV) regions. Central to the recruitment of AID to the IgV genes are factors that regulate the generation of single‐stranded DNA (ssDNA), the enzymatic substrate of AID. Here, we report that chicken DT40 cells lacking variant histone H3.3 exhibit reduced IgV sequence diversification. We show that this results from impairment of the ability of AID to access the IgV genes due to reduced formation of ssDNA during IgV transcription. Loss of H3.3 also diminishes IgV R‐loop formation. However, reducing IgV R‐loops by RNase HI overexpression in wild‐type cells does not affect IgV diversification, showing that these structures are not necessary intermediates for AID access. Importantly, the reduction in the formation of AID‐accessible ssDNA in cells lacking H3.3 is independent of any effect on the level of transcription or the kinetics of RNAPII elongation, suggesting the presence of H3.3 in the nucleosomes of the IgV genes increases the chances of the IgV DNA becoming single‐stranded, thereby creating an effective AID substrate.
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spelling pubmed-48830272016-10-06 Histone H3.3 promotes IgV gene diversification by enhancing formation of AID‐accessible single‐stranded DNA Romanello, Marina Schiavone, Davide Frey, Alexander Sale, Julian E EMBO J Articles Immunoglobulin diversification is driven by activation‐induced deaminase (AID), which converts cytidine to uracil within the Ig variable (IgV) regions. Central to the recruitment of AID to the IgV genes are factors that regulate the generation of single‐stranded DNA (ssDNA), the enzymatic substrate of AID. Here, we report that chicken DT40 cells lacking variant histone H3.3 exhibit reduced IgV sequence diversification. We show that this results from impairment of the ability of AID to access the IgV genes due to reduced formation of ssDNA during IgV transcription. Loss of H3.3 also diminishes IgV R‐loop formation. However, reducing IgV R‐loops by RNase HI overexpression in wild‐type cells does not affect IgV diversification, showing that these structures are not necessary intermediates for AID access. Importantly, the reduction in the formation of AID‐accessible ssDNA in cells lacking H3.3 is independent of any effect on the level of transcription or the kinetics of RNAPII elongation, suggesting the presence of H3.3 in the nucleosomes of the IgV genes increases the chances of the IgV DNA becoming single‐stranded, thereby creating an effective AID substrate. John Wiley and Sons Inc. 2016-05-24 2016-07-01 /pmc/articles/PMC4883027/ /pubmed/27220848 http://dx.doi.org/10.15252/embj.201693958 Text en © 2016 MRC Laboratory of Molecular Biology. Published under the terms of the CC BY 4.0 license This is an open access article under the terms of the Creative Commons Attribution 4.0 (http://creativecommons.org/licenses/by/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Articles
Romanello, Marina
Schiavone, Davide
Frey, Alexander
Sale, Julian E
Histone H3.3 promotes IgV gene diversification by enhancing formation of AID‐accessible single‐stranded DNA
title Histone H3.3 promotes IgV gene diversification by enhancing formation of AID‐accessible single‐stranded DNA
title_full Histone H3.3 promotes IgV gene diversification by enhancing formation of AID‐accessible single‐stranded DNA
title_fullStr Histone H3.3 promotes IgV gene diversification by enhancing formation of AID‐accessible single‐stranded DNA
title_full_unstemmed Histone H3.3 promotes IgV gene diversification by enhancing formation of AID‐accessible single‐stranded DNA
title_short Histone H3.3 promotes IgV gene diversification by enhancing formation of AID‐accessible single‐stranded DNA
title_sort histone h3.3 promotes igv gene diversification by enhancing formation of aid‐accessible single‐stranded dna
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4883027/
https://www.ncbi.nlm.nih.gov/pubmed/27220848
http://dx.doi.org/10.15252/embj.201693958
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