MAP kinase‐mediated phosphoacetylation of histone H3 and inducible gene regulation

Antimicrobial peptides (AMP) are defense effectors of the innate immunity playing a crucial role in the intestinal homeostasis with commensals and protection against pathogens. Herein we aimed to investigate AMP gene regulation by deciphering specific characteristics allowing their enhanced expression among innate immune genes, particularly those encoding proinflammatory mediators. Our emphasis was on epigenetic regulation of the gene encoding the AMP β-defensin 2 (HBD2), taken as a model of possibly specific induction, upon challenge with a commensal bacterium, compared with the proinflammatory cytokine IL-8. Using an in vitro model of colonic epithelial cells challenged with Escherichia coli K12, we showed that inhibition of histone deacetylases (HDAC) by trichostatin A dramatically enhanced induction of HBD2 expression, without affecting expression of IL-8. This mechanism was supported by an increased phosphorylation of histone H3 on serine S10, preferentially at the HBD2 promoter. This process occurred through activation of the IκB kinase complex, which also led to activation of NF-κB. Moreover, we demonstrated that NF-κB was modified by acetylation upon HDAC inhibition, partly by the histone acetyltransferase p300, and that both NF-κB and p300 supported enhanced induction of HBD2 expression. Furthermore, we identified additional genes belonging to antimicrobial defense and epithelial restitution pathways that showed a similar pattern of epigenetic control. Finally, we confirmed our finding in human colonic primary cells using an ex vivo organoid model. This work opens the way to use epigenetic pharmacology to achieve induction of epithelial antimicrobial defenses, while limiting the deleterious risk of an inflammatory response.

Section: Discussionsupporting

confidence: 50%

Histone deacetylase inhibition enhances antimicrobial peptide but not inflammatory cytokine expression upon bacterial challenge

Fischer

Scotet

Friedman

et al. 2016

“…In keeping, other well characterized histone phosphorylation events exhibit complex relationships during the cell cycle. For example, H3S10 and S28 are phosphorylated during periods of immediate-early gene induction or mitosis (23,27). The timing of mH2AS137 phosphorylation resembles that of linker histone H1, which is present during interphase and becomes hyperphosphorylated during mitosis (22).…”

Section: Resultsmentioning

confidence: 99%

“…Histone phosphorylation, in particular, has long been believed to play a direct role in mitotic chromatin compaction or chromosome condensation (e.g., H1 linker phosphorylation; H3S10ph and H3S28ph), although causality relationships remain unclear (22)(23)(24). Connection of histone phosphorylation to other physiologically relevant processes that lie outside of mitosis, such as apoptosis (H2BS14), DNA damage and repair (␥H2A.X), and inducible gene activation (H3S10), are also well documented (25)(26)(27).…”

mentioning

confidence: 99%

A phosphorylated subpopulation of the histone variant macroH2A1 is excluded from the inactive X chromosome and enriched during mitosis

Bernstein

Muratore-Schroeder²,

Diaz

et al. 2008

Histone variants play an important role in numerous biological processes through changes in nucleosome structure and stability and possibly through mechanisms influenced by posttranslational modifications unique to a histone variant. The family of histone H2A variants includes members such as H2A.Z, the DNA damageassociated H2A.X, macroH2A (mH2A), and H2ABbd (Barr bodydeficient). Here, we have undertaken the challenge to decipher the posttranslational modification-mediated ''histone code'' of mH2A, a variant generally associated with certain forms of condensed chromatin such as the inactive X chromosome in female mammals. By using female human cells as a source of mH2A, endogenous mH2A was purified and analyzed by mass spectrometry. Although mH2A is in low abundance compared with conventional histones, we identified a phosphorylation site, S137ph, which resides within the ''hinge'' region of mH2A. This lysine-rich hinge is an Ϸ30-aa stretch between the H2A and macro domains, proposed to bind nucleic acids. A specific antibody to S137ph was raised; by using this reagent, S137 phosphorylation was found to be present in both male and female cells and on both splice variants of the mH2A1 gene. Although mH2A is generally enriched on the inactive X chromosome in female cells, mH2AS137ph is excluded from this heterochromatic structure. Thus, a phosphorylated subpopulation of mH2A appears to play a unique role in chromatin regulation beyond X inactivation. We provide evidence that S137ph is enriched in mitosis, suggestive of a role in the regulation of mH2A posttranslational modifications throughout the cell cycle.macroH2A ͉ histone modifications ͉ phosphorylation

“…Histone phosphorylation occurs in many organisms and is associated with a wide range of biological functions, such as apoptosis (H2B S14P) (18), DNA repair (H2A.X S139P) (19), inducible gene activation (H3 S10P) (20), and mitosis (H3 S10P, H3 S28P, and T11P) (12,14,21). Whereas a mitosis-specific phosphorylation of H3 S10 and H3 S28 is necessary for the initiation of chromosome condensation in ciliates (22), a causal link is less clear in other organisms (23).…”

Section: Discussionmentioning

confidence: 99%

Serine 31 phosphorylation of histone variant H3.3 is specific to regions bordering centromeres in metaphase chromosomes

Hake

Garcia

Kauer

et al. 2005

171

133

Histones are the fundamental components of the nucleosome. Physiologically relevant variation is introduced into this structure through chromatin remodeling, addition of covalent modifications, or replacement with specialized histone variants. The histone H3 family contains an evolutionary conserved variant, H3.3, which differs in sequence in only five amino acids from the canonical H3, H3.1, and was shown to play a role in the transcriptional activation of genes. Histone H3.3 contains a serine (S) to alanine (A) replacement at amino acid position 31 (S31). Here, we demonstrate by both MS and biochemical methods that this serine is phosphorylated (S31P) during mitosis in mammalian cells. In contrast to H3 S10 and H3 S28, which first become phosphorylated in prophase, H3.3 S31 phosphorylation is observed only in late prometaphase and metaphase and is absent in anaphase. Additionally, H3.3 S31P forms a speckled staining pattern on the metaphase plate, whereas H3 S10 and H3 S28 phosphorylation localizes to the outer regions of condensed DNA. Furthermore, in contrast to phosphorylated general H3, H3.3 S31P is localized in distinct chromosomal regions immediately adjacent to centromeres. These findings argue for a unique function for the phosphorylated isoform of H3.3 that is distinct from its suspected role in gene activation. mitosis ͉ cell cycle ͉ subtype modification T he building blocks of eukaryotic chromatin are nucleosomes that consist of 147 bp of DNA wrapped around histone octamers containing two copies each of the core histones H3, H4, H2A, and H2B (1). Covalent modifications of core histones, mostly occurring at the N termini, such as acetylation, methylation, and phosphorylation, can alter the conformation of nucleosomes and͞or function as specific binding sites for enzymes that, in turn, alter chromatin structure (2-6). Alternatively, variation in chromatin can be introduced through the incorporation of variant histones into the nucleosome. For example, in mammals, in addition to the centromere-specific CENP-A variant, two nonallelic variants of the canonical histone H3 (H3.1) have been identified. One of these, H3.2, is closely related to H3.1 and only differs in a cysteine-serine substitution at amino acid position 96 and belongs to the family of S phase-dependent subtypes (7). In contrast, the second isoform, H3.3, is expressed throughout the cell cycle and differs from H3.1 in five amino acids. H3.3 contains a serine (S) at position 31, whereas an alanine (A) is found at this position in H3.1 and H3.2 (see Fig. 1 A). The other differences between H3.1͞H3.2 and H3.3 are substitutions in the globular domain of the proteins and are crucial for their distinctive deposition during cell cycle (8). In Drosophila cells, H3.3 is found predominantly at active loci (8) and is enriched in covalent modifications associated with active chromatin, such as K4 and K79 methylation (9). Recently, H3.1 and H3.3 were shown to be deposited into chromatin by two distinct histone chaperone complexes, CAF-1 and HIRA, which...