title: DNA methyltransferase 1 and DNA methylation patterning contribute to germinal center B-cell differentiation.
abstract: The phenotype of germinal center (GC) B cells includes the unique ability to tolerate rapid proliferation and the mutagenic actions of activation induced cytosine deaminase (AICDA). Given the importance of epigenetic patterning in determining cellular phenotypes, we examined DNA methylation and the role of DNA methyltransferases in the formation of GCs. DNA methylation profiling revealed a marked shift in DNA methylation patterning in GC B cells versus resting/naive B cells. This shift included significant differential methylation of 235 genes, with concordant inverse changes in gene expression affecting most notably genes of the NFkB and MAP kinase signaling pathways. GC B cells were predominantly hypomethylated compared with naive B cells and AICDA binding sites were highly overrepresented among hypomethylated loci. GC B cells also exhibited greater DNA methylation heterogeneity than naive B cells. Among DNA methyltransferases (DNMTs), only DNMT1 was significantly up-regulated in GC B cells. Dnmt1 hypomorphic mice displayed deficient GC formation and treatment of mice with the DNA methyltransferase inhibitor decitabine resulted in failure to form GCs after immune stimulation. Notably, the GC B cells of Dnmt1 hypomorphic animals showed evidence of increased DNA damage, suggesting dual roles for DNMT1 in DNA methylation and double strand DNA break repair.
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, Weill Cornell Medical College, New York, NY, USA.
authors.forename: Rita
authors.initials: R
authors.lastname: Shaknovich
authors.forename: Leandro
authors.initials: L
authors.lastname: Cerchietti
authors.forename: Lucas
authors.initials: L
authors.lastname: Tsikitas
authors.forename: Matthias
authors.initials: M
authors.lastname: Kormaksson
authors.forename: Subhajyoti
authors.initials: S
authors.lastname: De
authors.forename: Maria E
authors.initials: ME
authors.lastname: Figueroa
authors.forename: Gianna
authors.initials: G
authors.lastname: Ballon
authors.forename: Shao Ning
authors.initials: SN
authors.lastname: Yang
authors.forename: Nils
authors.initials: N
authors.lastname: Weinhold
authors.forename: Mark
authors.initials: M
authors.lastname: Reimers
authors.forename: Thomas
authors.initials: T
authors.lastname: Clozel
authors.forename: Karin
authors.initials: K
authors.lastname: Luttrop
authors.forename: Tomas J
authors.initials: TJ
authors.lastname: Ekstrom
authors.forename: Jared
authors.initials: J
authors.lastname: Frank
authors.forename: Aparna
authors.initials: A
authors.lastname: Vasanthakumar
authors.forename: Lucy A
authors.initials: LA
authors.lastname: Godley
authors.forename: Franziska
authors.initials: F
authors.lastname: Michor
authors.forename: Olivier
authors.initials: O
authors.lastname: Elemento
authors.forename: Ari
authors.initials: A
authors.lastname: Melnick
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D002454:Cell Differentiation / Q000235:genetics* / Q000276:immunology; D016000:Cluster Analysis; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism / Q000502:physiology*; D019175:DNA Methylation / Q000502:physiology*; D044127:Epigenesis, Genetic / Q000502:physiology; D020869:Gene Expression Profiling; D018858:Germinal Center / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D046228:Microarray Analysis; D012756:Sheep; D054928:Validation Studies as Topic
chemical_list: D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; C000619381:Dnmt1 protein, mouse