Deacetylase activity of histone deacetylase 3 is required for productive VDJ recombination and B-cell development

Abstract

Histone deacetylase 3 (HDAC3) is the catalytic component of NCoR/SMRT corepressor complexes that mediate the actions of transcription factors implicated in the regulation of B-cell development and function. We crossed Hdac3 conditional knockout mice with Mb1-Cre knockin animals to delete Hdac3 in early progenitor B cells. The spleens of Hdac3 CD43+ populations identified a defect in V H DJ H recombination with a severe reduction in productive rearrangements, which directly corresponded to the loss of pre-B cells from Hdac3 Δ/− bone marrow. For Hdac3 Δ/− B cells that did show productive VDJ rearrangement, there was significant skewing toward the incorporation of proximal V H gene segments and a corresponding reduction in distal V H gene segment use. Although transcriptional effects within these loci were modest, Hdac3 Δ/− progenitor cells displayed global changes in chromatin structure that likely hindered effective distal V-DJ recombination. Reintroduction of wild-type Hdac3 restored normal B-cell development, whereas an Hdac3 point mutant lacking deacetylase activity failed to complement this defect. Thus, the deacetylase activity of Hdac3 is required for the generation of mature B cells.istone deacetylase 3 (Hdac3) functions as the catalytic component of NCoR/SMRT corepressor complexes that are recruited by sequence-specific transcription factors to regulate transcription through the deacetylation of both histone and nonhistone proteins (1-3). Although bulk histone acetylation is generally controlled during replication by Hdac1 and Hdac2 (4, 5), Hdac3 is required for the maintenance of heterochromatin in some tissues (6, 7). Furthermore, the ability of Hdac3 to modulate chromatin accessibility has profound effects on gene transcription, DNA replication, and DNA repair (8-13). For example, hepatocyte-specific deletion of Hdac3 resulted in global changes in histone acetylation, nucleosomal compaction, and changes in gene expression (6). Although Hdac3 has robust deacetylase activity and is proposed to mediate the activity of some class II HDACs that lack intrinsic deacetylase function (14, 15), deacetylase inactive mutants of Hdac3 appeared to partially complement the phenotype of hepatocyte-specific Hdac3-knockout mice (16). This was interesting given that the livers of Albumin-Cre-Hdac3 −/− mice displayed phenotypes associated with global increases in histone acetylation, including a loss of heterochromatin (6, 9).The adaptive immune system has provided an excellent model for the study of higher-order chromatin structure and also provides a simple genetic system in which to dissect mechanisms of action for Hdac3. Lymphocytes rely on a series of recombinationdependent genome-editing processes, such as VDJ recombination and class-switch recombination, for their development and function. These recombination events are regulated through locus accessibility and require long-range chromatin interactions (17, 18). The Rag1 and Rag2 recombinases introduce DNA doublestrand breaks at recombination signal sequences, fol...

Role of HDACs in normal and malignant hematopoiesis

“…For pregerminal center (GC) B cell differentiation, BCL6 RD2 domain-dependent recruitment of HDAC2 mediates repression of the trafficking receptors S1pr1 and Gpr183, contributing to the clustering of B cells within follicles [68]. Conditional knockdown of HDAC3 in early progenitor B cells of mice resulted in impaired B cell maturation and a defect in VDJ recombination [69]. Specifically, HDAC3 is implicated in different complexes at different B cell differentiation stages.…”

Circadian Regulation of Immunity Through Epigenetic Mechanisms

“…At tissue level, lymphocytes including T cells CD8+, CD4+, and B cells show circadian oscillation in the entry/egress from the lymph nodes, and BMAL1 is necessary for this function by directing the circadian expression of key regulators of lymphocyte trafficking such as Ccr7 and S1pr1 (Druzd et al, 2017). Interestingly, histone acetylation at Ccr7, S1pr1, and S1pr4 promoters is modulated by HDAC3 in Tregs (Wang et al, 2015), while in B cells, Hdac3 deletion impairs VDJ recombination, implying epigenetic mechanism of chromatin conformation in the production of fully recombined B-cell receptor (Stengel et al, 2017). Whether the epigenetic remodeler complex HDAC3-NCoR-RevErbα regulates VDJ recombination should be addressed to find out the possibility of a direct link with the clock machinery in this crucial element of the adaptive immunity.…”

Integrative regulation of physiology by histone deacetylase 3

“…Deletion of Hdac3 in early B cell progenitors using Cd79a-Cre impedes B cell development owing to a substantial hindrance of distal V H - DJ H immunoglobulin heavy chain recombination, which is caused by altered chromatin structure that is thought to impair the formation of long-distance chromatin interactions (chromatin looping), which, notably, requires the catalytic activity of HDAC3 (REF. 131 ).…”