title: Regulation of epsilon germline transcription and switch region mutations by IgH locus 3' enhancers in transgenic mice.
abstract: Germline (GL) transcription is regulated by specific promoters and immunoglobulin heavy chain (IgH) 3' locus enhancers and is necessary for Ig class-switch recombination (CSR). We have generated different transgenic lines containing the GL epsilon promoter, switch (S) epsilon region, and constant (C) epsilon region with or without the DNase I-sensitive regions (HS) 3A-HS1,2 or HS3B-HS4 3' IgH enhancer pairs. The enhancerless construct was expressed in B cells activated by interleukin (IL)-4 and CD40, thus resembling regulation of the endogenous gene. Both enhancer-containing transgenes efficiently increased expression in B cells and were strongly up-regulated by stimuli. In addition, Sepsilon regions of the transgene containing HS3B-HS4 were mutated in activated, sorted B cells. Such mutations are known to precede CSR and are dependent on activation-induced cytidine deaminase (AID). Our findings show that all elements necessary for recruitment of the recombination machinery are present in the transgene containing HS3 and HS4. These enhancers probably provide something more specific than mere increased accessibility of switch regions. We propose that transcription factors binding the enhancers help to target the recombination machinery to the switch regions.
authors.affiliation: Department of Cell and Molecular Biology, Karolinska Institutet, SE-17177 Stockholm, Sweden.
authors.forename: Jurga
authors.initials: J
authors.lastname: Laurencikiene
authors.forename: Vytas
authors.initials: V
authors.lastname: Tamosiunas
authors.forename: Eva
authors.initials: E
authors.lastname: Severinson
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics*; D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D019013:CD40 Antigens / Q000494:pharmacology; D002843:Chromatin / Q000235:genetics; D003564:Cytidine Deaminase / Q000502:physiology; D004742:Enhancer Elements, Genetic / Q000502:physiology*; D005260:Female; D018703:Founder Effect; D018628:Gene Dosage; D005813:Genes, Synthetic; D018858:Germinal Center / Q000166:cytology / Q000276:immunology; D017578:Immunoglobulin Class Switching / Q000235:genetics*; D007127:Immunoglobulin Constant Regions / Q000235:genetics; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007139:Immunoglobulin epsilon-Chains / Q000235:genetics*; D015847:Interleukin-4 / Q000494:pharmacology; D019901:Locus Control Region / Q000235:genetics*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D020080:Tandem Repeat Sequences; D014158:Transcription, Genetic; D019076:Transgenes; D000098830:AICDA (Activation-Induced Cytidine Deaminase)
chemical_list: D020413:3' Untranslated Regions; D019013:CD40 Antigens; D002843:Chromatin; D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D007139:Immunoglobulin epsilon-Chains; D011993:Recombinant Fusion Proteins; D015847:Interleukin-4; D000098830:AICDA (Activation-Induced Cytidine Deaminase); D003564:Cytidine Deaminase