Immunoglobulin enhancers increase RNA polymerase 2 stalling at somatic hypermutation target sequences
Immunoglobulin enhancers increase RNA polymerase 2 stalling at somatic hypermutation target sequences
ABSTRACT Somatic hypermutation (SHM) drives the genetic diversity of immunoglobulin (Ig) genes in activated B cells and supports the generation of antibodies with increased affinity for antigen. SHM is targeted to Ig genes by their enhancers (DIVACs; diversification activators), but how the enhancers mediate this activity is unknown. We show using chicken DT40 B cells that highly active DIVACs increase the phosphorylation of RNA polymerase 2 (Pol2) and Pol2 occupancy in the mutating gene with little or no accompanying increase in elongation-competent Pol2 or production of full-length transcripts, indicating accumulation of stalled Pol2. DIVAC has similar effect also in human Ramos Burkitt lymphoma cells. The DIVAC-induced stalling is weakly associated with an increase in the detection of single-stranded DNA bubbles in the mutating target gene. We did not find evidence for antisense transcription, or that DIVAC functions by altering levels of H3K27ac or the histone variant H3.3 in the mutating gene. These findings argue for a connection between Pol2 stalling and cis-acting targeting elements in the context of SHM and thus define a mechanistic basis for locus-specific targeting of SHM in the genome. Our results suggest that DIVAC elements render the target gene a suitable platform for AID-mediated mutation without a requirement for increasing transcriptional output.
Alinikula Jukka、?enigl Filip、Tarsalainen Alina、Kyl?niemi Minna K.、Alt Frederic W.、Schatz David G.、Maman Yaakov、McDonald Jessica J.、Meng Fei-Long、Budzynska Paulina、Soikkeli Anni
Unit of Infections and Immunity, Institute of Biomedicine, University of TurkuInstitute of Molecular Genetics, Academy of Sciences of the Czech RepublicUnit of Infections and Immunity, Institute of Biomedicine, University of TurkuUnit of Infections and Immunity, Institute of Biomedicine, University of Turku||Turku Bioscience Centre, University of Turku and ?bo Akademi UniversityDepartment of Genetics, Harvard Medical School and Program in Cellular and Molecular Medicine, HHMI, Boston Children?ˉs HospitalDepartment of Immunobiology, Yale School of MedicineThe Azrieli Faculty of Medicine, Bar Ilan UniversityDepartment of Immunobiology, Yale School of Medicine||The Annenberg Public Policy CenterDepartment of Genetics, Harvard Medical School and Program in Cellular and Molecular Medicine, HHMI, Boston Children?ˉs Hospital||State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of SciencesUnit of Infections and Immunity, Institute of Biomedicine, University of TurkuUnit of Infections and Immunity, Institute of Biomedicine, University of Turku
基础医学分子生物学遗传学
Alinikula Jukka,?enigl Filip,Tarsalainen Alina,Kyl?niemi Minna K.,Alt Frederic W.,Schatz David G.,Maman Yaakov,McDonald Jessica J.,Meng Fei-Long,Budzynska Paulina,Soikkeli Anni.Immunoglobulin enhancers increase RNA polymerase 2 stalling at somatic hypermutation target sequences[EB/OL].(2025-03-28)[2025-05-11].https://www.biorxiv.org/content/10.1101/2021.09.16.460442.点此复制
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