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H4K16 versus H4K16Ac. The acetylation status of lysine 16 in histone H4 (represented as a blue circle) has a critical role in multiple functions in chromatin regulation throughout evolution as shown. Whereas acetylation of K16 is involved in active transcription and open chromatin, non-acetylated K16 is associated with gene silencing and heterochromatin compacted structures.

H4K16 versus H4K16Ac. The acetylation status of lysine 16 in histone H4 (represented as a blue circle) has a critical role in multiple functions in chromatin regulation throughout evolution as shown. Whereas acetylation of K16 is involved in active transcription and open chromatin, non-acetylated K16 is associated with gene silencing and heterochromatin compacted structures.

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Histone deacetylases (HDACs) catalyse the removal of acetyl groups from the N-terminal tails of histones. All known HDACs can be categorized into one of four classes (I-IV). The class III HDAC or silencing information regulator 2 (Sir2) family exhibits characteristics consistent with a distinctive role in regulation of chromatin structure. Accumula...

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... To gain insight into the molecular mechanism underlying the H4K16Ac reduction with in vitro aging, we analyzed the expression of MOF, the principal H4K16 histone acetyltransferase (Taipale et al. 2005;Smith et al. 2005), and the main H4K16 deacetylases, SIRT1 and SIRT2 (Vaquero et al. 2007), by RT-qPCR (Fig. 1G). We also examined the expression of TIP60, another acetyltransferase of H4K16 (Tang et al. 2013), and the expression of general histone deacetylases HDAC1 and HDAC2 (Miller et al. 2010) ( Figure S2). ...
... Since TSA is a general inhibitor of HDACs, we next checked the effect of nicotinamide (NAM), which is a specific inhibitor of sirtuins (Avalos et al. 2005), i.e., the major HDACs involved in H4K16Ac deacetylation (Vaquero et al. 2007) and whose expression remains unchanged in our in vitro aged cells. Again, the levels of H4K16Ac were significantly higher in NAM-treated HDFs in comparison to control HDFs ( Fig. 3D and E); however, there were no differences in the 53BP1-γH2AX colocalization ratio between Bleocin-treated and NAM + Bleocintreated cells in EP nor LP HDFs (Fig. 3F). ...
... Hypoacetylation was achieved using shRNAs to deplete MOF expression. Previous studies have described sirtuins as important H4K16Ac deacetylases (Vaquero et al. 2007), but our results indicate that, during in vitro aging, sirtuin expression levels remain unchanged in our cell model, while MOF expression was clearly decreased. Indeed, MOF is the major H4K16 lysine acetyltransferase in Drosophila and mammals (Taipale et al. 2005;Smith et al. 2005). ...
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... The mitochondrial deacetylase SIRT3 was shown to behave as a TSG in breast tissue with SIRT3 -/mice developing breast cancers, while human breast cancers have reduced SIRT3 expression (55). A direct TBX2-SIRT3 interaction would seem unlikely, although SIRT3 has been reported to localise to the nucleus to deacetylate H4K16, a known euchromatin mark (56). It is therefore plausible that TBX2 could reposition SIRT3 to reduce promoter-specific and/or global H4K16 acetylation, a phenomenon which has been reported in multiple tumour types. ...
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... Paradoxically, inhibition of Sirtuin2 enhanced antigen presentation in Mtb-infected M1-but not M2or M0-MΦs. As Entinostat likely reduces global histone acetylation (especially H3K18 acetylation), and sirtinol preferentially reduces H4K16 acetylation [54][55][56] , our data are consistent with the acetylation status of the histones of the ATG5 promoter related to autophagy. Figure 5l shows that Sirtuin2 blockade using sirtinol decreased Mtb survival in M1-, M2-, and M0-MФs. ...
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... Paradoxically, inhibition of Sirtuin2 enhanced antigen presentation in Mtb-infected M1-but not M2or M0-MΦs. As Entinostat likely reduces global histone acetylation (especially H3K18 acetylation), and sirtinol preferentially reduces H4K16 acetylation [54][55][56] , our data are consistent with the acetylation status of the histones of the ATG5 promoter related to autophagy. Figure 5l shows that Sirtuin2 blockade using sirtinol decreased Mtb survival in M1-, M2-, and M0-MФs. ...
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... Class III is composed of the sirtuin family and contains seven members (SIRT1 to 7), which share high sequence similarity with the yeast protein silent information regulator 2 (Sir2) . These HDACs require NAD + to catalyze the deacetylation reaction due to their conserved catalytic domain, whereas other HDACs rely on the binding of zinc molecule as an activator (Vaquero et al., 2007). SIRT1/2 shuttle between the nucleus and cytoplasm. ...
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... Eventually, H4K16ac was detected only in the wild-type cell line expressing VvMSA, while this histone mark was not observed in the three independently transformed VvMSA-RNAi cell lines. Studies in yeast, Arabidopsis and rice have already revealed differential functions for the acetylation at this specific position, lysine 16 of histone H4 [67,68]. Hyperacetylation of H4K16 in budding yeast has appeared to be involved in the stability of heterochromatin boundaries and the high-order compaction of chromatin [69]. ...
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In order to unravel the functions of ASR (Abscisic acid, Stress, Ripening-induced) proteins in the nucleus, we created a new model of genetically transformed grape embryogenic cells by RNAi-knockdown of grape ASR (VvMSA). Nuclear proteomes of wild-type and VvMSA-RNAi grape cell lines were analyzed by quantitative isobaric tagging (iTRAQ 8-plex). The most significantly up- or down-regulated nuclear proteins were involved in epigenetic regulation, DNA replication/repair, transcription, mRNA splicing/stability/editing, rRNA processing/biogenesis, metabolism, cell division/differentiation and stress responses. The spectacular up-regulation in VvMSA-silenced cells was that of the stress response protein VvLEA D-29 (Late Embryogenesis Abundant). Both VvMSA and VvLEA D-29 genes displayed strong and contrasted responsiveness to auxin depletion, repression of VvMSA and induction of VvLEA D-29. In silico analysis of VvMSA and VvLEA D-29 proteins highlighted their intrinsically disordered nature and possible compensatory relationship. Semi-quantitative evaluation by medium-throughput immunoblotting of eighteen post-translational modifications of histones H3 and H4 in VvMSA-knockdown cells showed significant enrichment/depletion of the histone marks H3K4me1, H3K4me3, H3K9me1, H3K9me2, H3K36me2, H3K36me3 and H4K16ac. We demonstrate that grape ASR repression differentially affects members of complex nucleoprotein structures and may not only act as molecular chaperone/transcription factor, but also participates in plant responses to developmental and environmental cues through epigenetic mechanisms.
... H4K16 acetylation triggers the unfolding of chromatin by disrupting the interaction between the nucleosomes, indicating active transcription [12]. In contrast, deacetylated H4K16 is usually associated with heterochromatin and transcriptional silencing [13]. For example, in female mammals, the inactive X chromosome is distinguished by lack of H4K16 acetylation [14]. ...
... While there are other lysine sites of H4 that can be acetylated (such as K5,K8, K12), K16 is the first and most frequently acetylated lysine of the H4, which is present in about 60% of the total H4 in mammalian cells [13]. Members of the MYST family of histone acetyltransferases (HAT), and class I and class III histone deacetylases (HDACs) control the balance of H4K16 acetylation. ...
... As mentioned above, Mof is only one of multiple enzymes that regulate H4K16Ac levels [13,[16][17][18][19]. The upregulated H4K16Ac levels could be directly related to increased acetyltransferases, decreased deacetylases, or both. ...
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Histone H4 lysine16 acetylation (H4K16Ac) modulates chromatin structure by serving as a switch from a repressive to a transcriptionally active state. This euchromatin mark is associated with active transcription. In this study, we investigated the effects of H4K16Ac on the expression of pro-fibrotic genes in lung fibroblasts from patients with idiopathic pulmonary fibrosis (IPF) and in an aging murine model of lung fibrosis. Methods: The lung tissues and fibroblasts from human IPF/non-IPF donors and from aged mice with/without bleomycin induced lung fibrosis were used in this study. The H4K16Ac levels were examined by immunohistochemistry or western blots. RNA silencing of H4K16Ac acetyltransferase Mof was used to reduce H4K16Ac levels in IPF fibroblasts. The effects of reduced H4K16Ac on pro-fibrotic gene expression were examined by western blots and real-time PCR. The association of H4K16Ac with these genes' promoter region were evaluated by ChIP assays. The gene expression profile in siRNA Mof transfected IPF cells were determined by RNA-Seq. The impact of H4K16Ac levels on lung fibrosis was evaluated in an aging murine model. Results: Aged mice with bleomycin induced lung fibrosis showed increased H4K16Ac levels. Human lung fibroblasts with siRNA Mof silencing demonstrated reduced H4K16Ac, and significantly down-regulated profibrotic genes, such as α-smooth muscle actin (α-SMA), collagen I, Nox4, and survivin. ChIP assays confirmed the associations of these pro-fibrotic genes' promoter region with H4K16Ac, while in siRNA Mof transfected cells the promoter/H4K16Ac associations were depleted. RNA-seq data demonstrated that Mof knockdown altered gene expression and cellular pathways, including cell damage and repair. In the aging mice model of persistent lung fibrosis, 18-month old mice given intra-nasal siRNA Mof from week 3 to 6 following bleomycin injury showed improved lung architecture, decreased total hydroxyproline content and lower levels of H4K16Ac. Conclusions: These results indicate a critical epigenetic regulatory role for histone H4K16Ac in the pathogenesis of pulmonary fibrosis, which will aid in the development of novel therapeutic strategies for age-related diseases such as IPF.
... 4,5 Many deacetylation substrates have already been identified, including histones (e.g. H4K16, H3K18) 6,7 as well as non-histone proteins like α-tubulin, 8 p300, 9 NFκB, 10 PEPCK1, 11 LDH1,12 HIF1α 13 and FOXO3 14 . ...
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Sirtuin2 (Sirt2) with its NAD+-dependent deacetylase and defatty-acylase activities plays a central role in the regulation of specific cellular functions. Dysregulation of Sirt2 activity has been associated with the pathogenesis of many diseases, thus making Sirt2 a promising target for pharmaceutical intervention. Herein, we present new high affinity Sirt2 selective Sirtuin-Rearranging Ligands (SirReals) that inhibit both Sirt2-dependent deacetylation and defatty-acylation in vitro and in cells. We show that dual inhibition of Sirt2 results in strongly reduced levels of the oncogene c-Myc and an inhibition of cancer cell migration. Furthermore, we describe the development of a NanoBRET-based assay for Sirt2, thereby providing a method to study cellular target engagement for Sirt2 in a straightforward and accurately quantifiable manner. Applying this assay, we could confirm cellular Sirt2 binding of our new Sirt2 inhibitors and correlate their anticancer effects with their cellular target engagement.
... Recombinant mSir2α could deacetylate the acetylated histone peptide in a manner similar to SIR2, thus indicating that transcriptional silencing by SIR2 may also function in mammals. The NAD + - Functions in cellular senescence and ageing Sirtuin1 Nucleus cytoplasm Deacetylation H3K9, H4K16 [11,49], p53 [19,20], p73 [135], FOX01, FOX03a, FOX04 [25,26,28,136], PTEN [137], NICD [80], MEF2 [138], HIF-1α, HIF-2α [139][140][141], TAF(I) [142] SREBP-1 c [143], βcatenin [144], RelA/p65 [32,145], PGC1α [43], BMAL1, Per2 [146,147], Ku70 [46], XPA [148], SMAD7 [52], cortactin [106], IRS-2 [149,150], APE1 [47], PCAF [151], TIP60 [152], p300 [25,[153][154][155], SUV39H1 [50], AceCS1 [54,156], PPARγ [40], ERα [157], AR [158], LXR [56] Longevity [11], Cell cycle arrest [20], Cellular senescence [140] Glucose metabolism [43], DNA repair [46,148] Cell migration [52], Insulin secretion [149], Neuroprotection [150], DNA damage [151,153], Sirtuin 2 Cytoplasm Deacetylation H4K16 [159], H3K56 [153], α-tubulin [160] Deacetylation of tubulin [160] Sirtuin 3 ...
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Sirtuin1 is a nutrient-sensitive class III histone deacetylase which is a well-known regulator of organismal lifespan. It has been extensively studied for its role in metabolic regulation as well. Along with its involvement in ageing and metabolism, Sirtuin1 directly deacetylates many critical proteins controlling cardiovascular pathophysiology. Studies using conditional expression and deletion of Sirtuin1 have revealed that it functions in a highly tissue/organ-specific manner. In the vasculature, Sirtuin1 controls endothelial homoeostasis by governing the expression of inflammatory mediators, oxidants and essential transcription factors. Adding to this complexity, Sirtuin1 expression and/or function is also governed by some of these target proteins. Therefore, the importance of better understanding the organ and tissue specificity of Sirtuin1 is highly desirable. Considering the huge volume of research done in this field, this review focuses on Sirtuin1 targets regulating vascular endothelial function. Here, we summarize the discovery of Sirtuin1 as a transcription controller and the further identification of direct target proteins involved in the vascular physiology. Overall, this review presents a holistic picture of the complex cross-talk involved in the molecular regulation of vascular physiology by Sirtuin1.
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