title: E2A acts in cis in G1 phase of cell cycle to promote Ig gene diversification.
abstract: Rearranged Ig genes undergo diversification in sequence and structure initiated by the DNA deaminase, activation-induced deaminase. Ig genes must be transcribed for diversification to occur, but whether there are additional requirements for cis activation has not been established. Here we show, by chromatin immunoprecipitation, that the regulatory factor E2A associates with the rearranged Ig lambda(R) gene in the chicken DT40 B cell line, which performs constitutive Ig gene diversification. By analysis of a DT40 derivative in which polymerized lactose operator tags the rearranged lambda(R) gene, we show that E2A must function in cis to promote diversification and that stimulation of diversification in cis depends on the E2A activation domains. By direct imaging, we show that lambda(R)/E2A colocalizations are most prominent in G(1). We further show that expression of the E2A antagonist Id1 prevents lambda(R)/E2A colocalizations in G(1) and impairs diversification but not transcription of lambda(R). Thus, E2A acts in cis to promote Ig gene diversification, and G(1) phase is the critical window for E2A action.
authors.affiliation: Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195, USA.
authors.forename: Munehisa
authors.initials: M
authors.lastname: Yabuki
authors.forename: Ellen C
authors.initials: EC
authors.lastname: Ordinario
authors.forename: W Jason
authors.initials: WJ
authors.lastname: Cummings
authors.forename: Monica M
authors.initials: MM
authors.lastname: Fujii
authors.forename: Nancy
authors.initials: N
authors.lastname: Maizels
mesh_terms: D000818:Animals; D000916:Antibody Diversity / Q000235:genetics*; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D045744:Cell Line, Tumor; D002645:Chickens; D024721:E-Box Elements / Q000235:genetics*; D016193:G1 Phase / Q000235:genetics*; D015328:Gene Rearrangement, B-Lymphocyte, Light Chain; D005803:Genes, Immunoglobulin; D007146:Immunoglobulin lambda-Chains / Q000096:biosynthesis / Q000235:genetics; D051796:Inhibitor of Differentiation Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D007544:Isopropyl Thiogalactoside / Q000031:analogs & derivatives / Q000502:physiology; D051820:TCF Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D058125:Transcription Factor 7-Like 1 Protein
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D007146:Immunoglobulin lambda-Chains; D051796:Inhibitor of Differentiation Proteins; D007544:Isopropyl Thiogalactoside; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; C070641:isopropyl-beta-galactopyranoside