title: A source of the single-stranded DNA substrate for activation-induced deaminase during somatic hypermutation.
abstract: During somatic hypermutation (SHM), activation-induced deaminase (AID) mutates deoxycytidine on single-stranded DNA (ssDNA) generated by the transcription machinery, but the detailed mechanism remains unclear. Here we report a higher abundance of RNA polymerase II (Pol II) at the immunoglobulin heavy-chain variable (Igh-V) region compared with the constant region and partially transcribed Igh RNAs, suggesting a slower Pol II progression at Igh-V that could result in some early/premature transcription termination after prolonged pausing/stalling of Pol II. Knocking down RNA-exosome complexes, which could decrease premature transcription termination, leads to decreased SHM. Knocking down Spt5, which can augment premature transcription termination, leads to increase in both, SHM and the abundance of ssDNA substrates. Collectively, our data support the model that, following the reduction of Pol II progression (pausing or stalling) at the Igh-V, additional steps such as premature transcription termination are involved in providing ssDNA substrates for AID during SHM.
authors.affiliation: Department of Cell Biology, Albert Einstein College of Medicine, Bronx New York 10461, USA.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Cell Biology, Albert Einstein College of Medicine, Bronx New York 10461, USA.
authors.forename: Manxia
authors.initials: M
authors.lastname: Fan
authors.affiliation: Department of Cell Biology, Albert Einstein College of Medicine, Bronx New York 10461, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Kalis
authors.affiliation: Department of Cell Biology, Albert Einstein College of Medicine, Bronx New York 10461, USA.
authors.forename: Lirong
authors.initials: L
authors.lastname: Wei
authors.affiliation: Department of Cell Biology, Albert Einstein College of Medicine, Bronx New York 10461, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Scharff
mesh_terms: D001402:B-Lymphocytes / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D002051:Burkitt Lymphoma / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D045744:Cell Line, Tumor; D003564:Cytidine Deaminase / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D017578:Immunoglobulin Class Switching; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D027041:Somatic Hypermutation, Immunoglobulin; D000098830:AICDA (Activation-Induced Cytidine Deaminase)
chemical_list: D004277:DNA, Single-Stranded; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D012319:RNA Polymerase II; D000098830:AICDA (Activation-Induced Cytidine Deaminase); D003564:Cytidine Deaminase