Document Detail


Histone H2A and H2B are monoubiquitinated at AID-targeted loci.
MedLine Citation:
PMID:  20661291     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Somatic hypermutation introduces base substitutions into the rearranged and expressed immunoglobulin (Ig) variable regions to promote immunity. This pathway requires and is initiated by the Activation Induced Deaminase (AID) protein, which deaminates cytidine to produce uracils and UG mismatches at the Ig genes. Subsequent processing of uracil by mismatch repair and base excision repair factors contributes to mutagenesis. While selective for certain genomic targets, the chromatin modifications which distinguish hypermutating from non-hypermutating loci are not defined. METHODOLOGY/PRINCIPAL FINDINGS: Here, we show that AID-targeted loci in mammalian B cells contain ubiquitinated chromatin. Chromatin immunoprecipitation (ChIP) analysis of a constitutively hypermutating Burkitt's B cell line, Ramos, revealed the presence of monoubiquitinated forms of both histone H2A and H2B at two AID-associated loci, but not at control loci which are expressed but not hypermutated. Similar analysis using LPS activated primary murine splenocytes showed enrichment of the expressed V(H) and Sgamma3 switch regions upon ChIP with antibody specific to AID and to monoubiquitinated H2A and H2B. In the mechanism of mammalian hypermutation, AID may interact with ubiquitinated chromatin because confocal immunofluorescence microscopy visualized AID colocalized with monoubiquitinated H2B within discrete nuclear foci. CONCLUSIONS/SIGNIFICANCE: Our results indicate that monoubiquitinated histones accompany active somatic hypermutation, revealing part of the histone code marking AID-targeted loci. This expands the current view of the chromatin state during hypermutation by identifying a specific nucleosome architecture associated with somatic hypermutation.
Authors:
Glen M Borchert; Nathaniel W Holton; Kevin A Edwards; Laura A Vogel; Erik D Larson
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2010-07-16
Journal Detail:
Title:  PloS one     Volume:  5     ISSN:  1932-6203     ISO Abbreviation:  PLoS ONE     Publication Date:  2010  
Date Detail:
Created Date:  2010-07-27     Completed Date:  2010-10-28     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101285081     Medline TA:  PLoS One     Country:  United States    
Other Details:
Languages:  eng     Pagination:  e11641     Citation Subset:  IM    
Affiliation:
School of Biological Sciences, Illinois State University, Normal, Illinois, United States of America.
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MeSH Terms
Descriptor/Qualifier:
Animals
Blotting, Western
Cell Line, Tumor
Cells, Cultured
Chromatin / metabolism
Chromatin Immunoprecipitation
Cytidine Deaminase / metabolism*
Histones / metabolism*
Humans
Mice
Microscopy, Confocal
Microscopy, Fluorescence
Polymerase Chain Reaction
Ubiquitination / physiology*
Grant Support
ID/Acronym/Agency:
R15CA137608/CA/NCI NIH HHS
Chemical
Reg. No./Substance:
0/Chromatin; 0/Histones; EC 3.5.4.5/Cytidine Deaminase
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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