B cell Sirt1 deacetylates histone and non-histone proteins for epigenetic modulation of AID expression and the antibody response

Abstract

Activation-induced cytidine deaminase (AID) mediates immunoglobulin class switch DNA recombination (CSR) and somatic hypermutation (SHM), critical processes for maturation of the antibody response. Epigenetic factors, such as histone deacetylases (HDACs), would underpin B cell differentiation stage–specific AID expression. Here, we showed that NAD+-dependent class III HDAC sirtuin 1 (Sirt1) is highly expressed in resting B cells and down-regulated by stimuli inducing AID. B cell Sirt1 down-regulation, deprivation of NAD+ cofactor, or genetic Sirt1 deletion reduced deacetylation of Aicda promoter histones, Dnmt1, and nuclear factor–κB (NF-κB) p65 and increased AID expression. This promoted class-switched and hypermutated T-dependent and T-independent antibody responses or led to generation of autoantibodies. Genetic Sirt1 overexpression, Sirt1 boost by NAD+, or allosteric Sirt1 enhancement by SRT1720 repressed AID expression and CSR/SHM. By deacetylating histone and nonhistone proteins (Dnmt1 and NF-κB p65), Sirt1 transduces metabolic cues into epigenetic changes to play an important B cell–intrinsic role in modulating antibody and autoantibody responses.

Integrative transcriptome and chromatin landscape analysis reveals distinct epigenetic regulations in human memory B cells

“…Buffy coats were obtained from South Texas Blood and Tissue Center, San Antonio, TX. Samples were obtained from seven healthy and non-immuno-compromised human subjects of different ages, 20-39, four males, three females of a different races, and ethnic backgrounds (Subjects A-G) (Supplementary Table 1) 78 . All experiments involving human samples were approved by the Institutional Review Board (IRB) of UTHSCSA and written informed consent was obtained.…”

“…In all seven cases, B cells were subjected to pre-and-post isolation phenotypic analysis using the following surface markers and fluorophores: PEcy7-anti-human-CD19 mAb (clone H1B19; Biolegend; 1:100), PE-anti-human-CD27 mAb (clone M-T271; Biolegend; 1:100), BV421-anti-human-IgD mAb (clone IA6-2; Biolegend; 1:100), FITC-anti-human-IgG mAb (clone G18-145; BD Pharmingen; 1:100), APC-anti-human-IgA mAb (clone IS11-8E10; Miltenyi Biotec; 1:100), and APC-Cy7-anti-IgM mAb (clone MHM-88, Biolegend; 1:100). Data were analyzed using FlowJo software version 10.6.2 (FlowJo LLC) 78 .…”

“…Total PBMCs were stained with FITC-anti-human-IgG mAb (clone G18-145; BD Pharmingen; 1:100), APC-anti-human-IgA mAb (clone IS11-8E10; Miltenyi Biotec; 1:100) and APC-Cyanine7-anti-human-CD27 mAb (clone M-T271; Biolegend; 1:100), BV421-anti-human-IgD mAb (clone IA6-2; Biolegend; 1:100), PE-Cyanine7-anti-human-CD19 (clone HIB19; Tonbo Biosciences; 1:100). Single cell suspension of tonsil cells were stained with APC-Cyanine7-anti-human-CD27 mAb (clone M-T271; Biolegend; 1:100), BV421-anti-human-IgD mAb (clone IA6-2; Biolegend; 1:100), PE-Cyanine7-anti-human-CD19 (clone HIB19; Tonbo Biosciences; 1:100), BV510-anti-human-CD138 mAb (clone MI15 Biolegend; 1:100), BV650-anti-human-CD38 mAb (clone HB-7; Biolegend; 1:100) 30 , 32 , 78 . For intracellular staining, cells were surface stained followed by incubation with the BD Cytofix/Cytoperm buffer at 4 °C for 20 min.…”

“…The human Igκ locus comprises 39 functional Vκ genes and 5 Jκ genes; the human Igλ locus comprises 30 functional Vλ genes segregated into 10 subgroups and 5 functional Jλ-Cλ clusters. IgH and IgL gene expression profiles were organized in stacked histograms to depict relative usage 39,80 28,78 . RNA was extracted using the Directzol RNA Microprep Kit (Zymogen Research) from CD27 -IgD + , CD27 + IgD + , CD27 + IgG + , and CD27 + IgA + B cells of subjects B, C, and G. cDNA was synthesized from RNA with the SuperScript III First-Strand Synthesis System (Invitrogen) using oligo-dT primer.…”

Estrogen Reverses HDAC Inhibitor-Mediated Repression of Aicda and Class-Switching in Antibody and Autoantibody Responses by Downregulation of miR-26a

“…As we have suggested, such mediators, including DNA methylases, histone posttranslational modifiers, such as methyltransferases and acetyltransferases and non-coding RNAs, such as microRNAs (miRNAs), modulate B cell functions. They interact with genetic programs to regulate B cell functions, such as CSR, SHM and plasma cell differentiation, thereby informing the antibody response (1,2,22). We have shown that in addition to DNA methylation and histone acetylation in the Aicda locus, select miRNAs also provide an important mechanism for modulation of AID expression.…”