title: H3 trimethyl K9 and H3 acetyl K9 chromatin modifications are associated with class switch recombination.
abstract: Class switch recombination (CSR) involves a DNA rearrangement in the Ig heavy chain (IgH) gene that allows the same variable (V) region to be expressed with any one of the downstream constant region (C) genes to encode antibodies with many different effector functions. One hypothesis for how CSR is targeted to different C region genes is that histone modifications increase accessibility and/or recruit activation-induced cytosine deaminase (AID) and its associated processes to particular donor and recipient switch regions. In this work, we identified H3 acetyl K9 and H3 trimethyl K9 as histone modifications that correlate with the recombining pair of donor and recipient switch regions. The appearance of H3 trimethyl K9 is surprising because usually it is thought to mark silent genes and heterochromatin. Nevertheless, the time course of appearance of these histone modifications, the regions in IgH they associate with, and their appearance independent of AID damage suggest that both modifications play a role in targeting CSR.
authors.affiliation: Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
authors.forename: Fei Li
authors.initials: FL
authors.lastname: Kuang
authors.forename: Zhonghui
authors.initials: Z
authors.lastname: Luo
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Scharff
mesh_terms: D000107:Acetylation; D000818:Animals; D042002:Chromatin Assembly and Disassembly; D043525:Cytosine Deaminase / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D017578:Immunoglobulin Class Switching; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D008745:Methylation; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D006657:Histones; D007143:Immunoglobulin Heavy Chains; D043525:Cytosine Deaminase