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Valproic acid in association with sodium valproate (VPA) is an important anticonvulsant drug used for decades to treat neurological disorders. VPA also acts as an epigenetic modulator by inhibiting histone deacetylases, permitting histone acetylation, affecting the DNA and histone methylation status and gene expression, and inducing chromatin remodeling. Insects represent an important animal model for studies in several areas of science. Their high phenotypic plasticity makes them alternative models for epigenetic studies. This brief review emphasizes recent reports on insect epigenetics and the contribution of studies on the VPA action in insects, including effects on epigenetic markers, extending the pharmacological understanding of the potential of this drug, and demonstrating the usefulness of insects as an alternative animal model to drug studies. Resumo O ácido valproico associado ao valproato de sódio (VPA) é um importante agente anticonvulsivo usado há décadas no tratamento de distúrbios neurológicos. Também atua como um modulador epigenético ao inibir as desacetilases de histonas, permitindo a acetilaçao de histonas, afetando o estado de metilação do DNA e das histonas e a expressão gênica, e induzindo a remodelação da cromatina. Os insetos representam um importante modelo animal para estudos em diversas áreas da ciência e dada a sua alta plasticidade fenotípica os torna modelos alternativos para estudos epigenéticos e de resposta a agentes moduladores epigenéticos. Esta breve revisão enfatiza relatos recentes sobre epigenética em insetos e a contribuição de estudos sobre a ação do VPA nesse grupo animal, incluindo efeitos sobre marcadores epigenéticos, estendendo a compreensão farmacológica do potencial desta droga e demonstrando a utilidade dos insetos como um modelo animal alternativo para estudos de drogas.

Fatty acids (FAs) rapidly and efficiently reduce cardiac glucose uptake in the Randle cycle or glucose-FA cycle. This fine-tuned physiological regulation is critical to allow optimal substrate allocation during fasted and fed states. However, the mechanisms involved in the direct FA-mediated control of glucose transport have not been totally elucidated yet. We previously reported that leucine and ketone bodies, other cardiac substrates, impair glucose uptake by increasing global protein acetylation from acetyl-CoA. As FAs generate acetyl-CoA as well, we postulated that protein acetylation is enhanced by FAs and participates in their inhibitory action on cardiac glucose uptake. Here, we demonstrated that both palmitate and oleate promoted a rapid increase in protein acetylation in primary cultured adult rat cardiomyocytes, which correlated with an inhibition of insulin-stimulated glucose uptake. This glucose absorption deficit was caused by an impairment in the translocation of vesicles containing the glucose transporter GLUT4 to the plasma membrane, although insulin signaling remained unaffected. Interestingly, pharmacological inhibition of lysine acetyltransferases (KATs) prevented this increase in protein acetylation and glucose uptake inhibition induced by FAs. Similarly, FA-mediated inhibition of insulin-stimulated glucose uptake could be prevented by KAT inhibitors in perfused hearts. To summarize, enhanced protein acetylation can be considered as an early event in the FA-induced inhibition of glucose transport in the heart, explaining part of the Randle cycle. Our results show that cardiac metabolic overload by oleate or palmitate leads to increased protein acetylation inhibiting GLUT4 translocation to the plasma membrane and glucose uptake. This observation suggests an additional regulation mechanism in the physiological glucose-FA cycle originally discovered by Randle.

Chagas' disease or American trypanosomiasis, caused by Trypanosoma cruzi infection, is an endemic disease in Latin America, which has spread worldwide in the past years. The drugs presently used for treatment have shown limited efficacy due to the appearance of resistant parasites and severe side effects. Some of the most recent studies on anti-parasitic drugs have been focused on protein acetylation, a reversible reaction modulated by Acetyl Transferases (KATs) and Deacetylases (KDACs). We have previously reported the anti-parasite activity of resveratrol (RSV), an activator of KDACs type III (or sirtuins), and showed that this drug can reduce the growth of T. cruzi epimastigotes and the infectivity of trypomastigotes. Since RSV is now widely used in humans due to its beneficial effects as an antioxidant, it has become an attractive candidate as a repurposing drug. In this context, the aim of the present study was to evaluate the ability of this drug to protect three different types of host cells from parasite infection. RSV treatment before parasite infection reduced the percentage of infected cells by 50-70% depending on the cell type. Although the mammalian cell lines tested showed different sensitivity to RSV, apoptosis was not significantly affected, showing that RSV was able to protect cells from infection without the activation of this process. Since autophagy has been described as a key process in parasite invasion, we also monitored this process on host cells pretreated with RSV. The results showed that, at the concentrations and incubation times tested, autophagy was not induced in any of the cell types evaluated. Our results show a partial protective effect of RSV in vitro, which justifies extending studies to an in vivo model to elucidate the mechanism by which this effect occurs.

Sevoflurane (Sev) might cause neurotoxicity in elderly rats. However, the role of Lin28A in Sev-induced neurotoxicity remains unclear in elderly rats. In this study, elderly rats were used to construct an Sev-induced nerve injury model. Learning and memory abilities were assessed by Morris water maze (MWM) trainings; pathological alterations in hippocampal region were assessed by HE staining; neuronal apoptosis was assessed by TUNEL; related protein expression was analyzed by immunofluorescence, immunohistochemistry, and Western blotting. Results of this study showed that Sev treatment caused nerve injury and cognitive dysfunction in elderly rats, with increased neuronal apoptosis and decreased Lin28A levels. Pathological impairment and learning and memory abilities of elderly rats were significantly improved after forced overexpression of Lin28A using AAV, accompanied by decreased expression of CD68, Iba-1, and GFAP. TUNEL analysis showed that Lin28A overexpression significantly reversed Sev-induced neuronal apoptosis. Further mechanistic analysis showed that Lin28A significantly promoted SIRT1 expression, which further reversed Sev-induced Tau acetylation at lysine 280 and 686 and Tau hyperphosphorylation, thereby alleviating nerve injury and cognitive dysfunction in elderly rats. The introduction of SIRT1 inhibitor EX527 further confirmed the involvement of SIRT1 in the regulation of Lin28A in elderly rats. In conclusion, our findings demonstrated that Lin28A reduced sevoflurane-induced nerve injury and cognitive dysfunction by inhibiting Tau acetylation and phosphorylation via activating SIRT1 in elderly rats.

Histone deacetylase 6 (HDAC6) is known to deacetylate amino acid lysine in alpha-tubulin. However, the functional role of HDAC6 in the progression of cardiac disease remains uncertain. The functional role of HDAC6 in the hearts was examined using transgenic (TG) mice expressing either human wild-type HDAC6, deacetylase inactive HDAC6 (HDAC6supH216A, H611A/sup), and human HDAC6 replaced all serine or threonine residues with aspartic acid at N-terminal 1- 43 amino acids (HDAC6supNT-allD/sup) specifically in the hearts. Overexpression of wild-type HDAC6 significantly reduced acetylated tubulin levels, and overexpression of HDAC6supH216A, H611A/supsignificantly increased it in the mouse hearts. Detectable acetylated tubulin disappeared in HDAC6supNT-allD/supTG mouse hearts. Neither histological alteration nor alteration of cardiac function was observed in the HDAC6 TG mouse hearts. To analyze the role of HDAC6 and acetylated tubulin in disease conditions, we examined HDAC6 in isoprenaline-induced hypertrophy or pressure-overload hypertrophy (TAC). No obvious alteration in the heart weight/body weight ratio or gene expressions of hypertrophic markers between NTG and HDAC6supNT-allD/supmice was observed following treatment with isoprenaline. In contrast, a marked reduction in the shortening fraction and dilated chamber dilatation was detected in the HDAC6supNT-allD/supTG mouse hearts 2 weeks after TAC. A sustained low level of acetylated tubulin and acetylated cortactin was observed in the TAC HDAC6supNT-allD/supTG mouse hearts. Cardiac HDAC6 activity that can regulate acetylated levels of tubulin and cortactin may be critical factors involved in cardiac disease such as pressure-overload hypertrophy.

Early life stress (ELS) can cause long-term changes in gene expression, affect cognition, mood, and behavior, and increase susceptibility to post-traumatic stress disorder (PTSD) in adulthood, in which the histone acetylation plays a crucial role. Studies have found that environmental enrichment (EE) mitigated the unfavorable outcomes of ELS. However, the underlying mechanism of the histone acetylation is not yet completely clear. The purpose of this study was to explore the effect of EE on the histone acetylation after ELS. In this study, using single prolonged stress (SPS) paradigm in early adolescent rats explored the long-term effects of ELS on behavior, the activity of histone acetyltransferases (HATs) and histone deacetylases (HDACs), as well as the acetylation levels of the lysine 9 site of histone H3 (H3K9) and lysine 12 site of histone H4 (H4K12) in the hippocampus and amygdala. Meanwhile, the protective effects of EE intervention were examined. We found that adult male rats exposed to ELS showed behavioral changes, including reduced locomotor activity, increased anxiety-like behaviors, impaired spatial learning and memory, enhanced contextual and cued fear memory, and the HATs/HDACs ratio and acetyl H3K9 (Ac-H3K9) and acetyl H4K12 (Ac-H4K12) were increased in the hippocampus and decreased in the amygdala. Furthermore, EE attenuated the behavioral abnormalities from ELS, possibly through down-regulating the activity of HATs in the hippocampus and up-regulating HDACs activities in the amygdala. These finding suggested that EE could ameliorate ELS-induced PTSD-like behaviors by regulating histone acetylation in the hippocampus and amygdala, reducing the susceptibility to PTSD in adulthood.

Myeloid-derived suppressor cells (MDSCs) are a major immunosuppressive population in the tumor microenvironment,inhibiting anti-tumor immune response and exerting pro-tumorigenic effect. CCAAT/enhancer-binding protein beta (C/EBPβ), a key transcription factor indispensable for myelopoiesis, plays a fundamental role in regulating expansion and activation of MDSCs. Lysine acetylation can regulate functions of transcription factors. However, the role of C/EBPβ acetylation modification in MDSCs has not been reported.MDSCs derived from the spleens of tumor-bearing mice (TB-SP-MDSCs) were isolated by immunomagnetic beads. Bone marrow derived MDSCs were induced by IL-6 and GM-CSF. Western-blot was used to detect the expression of P300 and co-immunoprecipitation (CO-IP) was used to detect the C/EBPβ acetylation in MDSCs. Inhibitor C646 was used to specificly inhibit P300 activity.In this study, we found that C/EBPβ was acetylated by acetyltransferase P300 in MDSCs. A P300-mediated C/EBPβ acetylation enhanced C/EBPβ transactivation activity on arginase 1 (Arg-1) gene promoter. Inhibition of P300 activity downregulated the inhibitory effects of MDSCs in vitro and attenuated pro-tumorigenic effects of MDSCs in vivo. Additionally, IL-6 from tumor microenvironment could upregulate the expression of P300 and enhance C/EBPβ acetylation in MDSCs.In general, a P300-mediated C/EBPβ acetylation enhanced C/EBPβ transactivation activity on Arg-1 promoter, thus promoting immunosuppressive function of MDSCs. In view of the critical role of P300 in regulating MDSCs, P300 might be a potential target of anti-tumor immunotherapy.

Lysyl oxidase-like 2 (LOXL2) is a member of the scavenger receptor cysteine-rich (SRCR) repeat carrying LOX family. Although LOXL2 is suspected to be involved in histone association and chromatin modification, the role of LOXL2 in epigenetic regulation during tumorigenesis and cancer progression remains unclear. Here, we report that nuclear LOXL2 associates with histone H3 and catalyzes H3K36ac deacetylation and deacetylimination. Both the N-terminal SRCR repeats and the C-terminal catalytic domain of LOXL2 carry redundant deacetylase catalytic activity. Overexpression of LOXL2 markedly reduced H3K36 acetylation and blocked H3K36ac-dependent transcription of genes, including c-MYC, CCND1, HIF1A, and CD44. Consequently, LOXL2 overexpression reduced cancer cell proliferation in vitro and inhibited xenograft tumor growth in vivo. In contrast, LOXL2 deficiency resulted in increased H3K36 acetylation and aberrant expression of H3K36ac-dependent genes involved in multiple oncogenic signaling pathways. Female LOXL2-deficient mice spontaneously developed uterine hypertrophy and uterine carcinoma. Moreover, silencing LOXL2 in cancer cells enhanced tumor progression and reduced the efficacy of cisplatin and anti-programmed cell death 1 (PD-1) combination therapy. Clinically, low nuclear LOXL2 expression and high H3K36ac levels corresponded to poor prognosis in uterine endometrial carcinoma patients. These results suggest that nuclear LOXL2 restricts cancer development in the female reproductive system via the regulation of H3K36ac deacetylation. Significance: LOXL2 loss reprograms the epigenetic landscape to promote uterine cancer initiation and progression and repress the efficacy of anti–PD-1 immunotherapy, indicating that LOXL2 is a tumor suppressor.

Site-selective acetylation of a single lysine residue in a protein that reaches a lysine acetyltransferase's accuracy, precision, and reliability is challenging. Here, we report a peptide-guided, proximity-driven group transfer reaction that acetylates a single lysine residue, Lys 248, of the fragment crystallizable region (Fc region) in the heavy chain of the human Immunoglobulin G (IgG). An Fc-interacting peptide bound with the Fc domain and positioned a phenolic ester close to Lys 248, which induced a nucleophilic reaction and resulted in the transfer of an acetyl group to Lys 248. The acetylation reaction proceeded to a decent yield under the physiological condition without the need for deglycosylation, unnatural amino acids, or catalysts. Along with acetylation, functional moieties such as azide, alkyne, fluorescent molecules, or biotin could also be site-selectively installed on Lys 248, allowing IgG's further derivatization. We then synthesized an antibody-lipid conjugate and constructed antibody-conjugated liposomes (immunoliposomes), targeting HER2-positive (HER2+) cancer cells. We also built a bispecific antibody complex (bsAbC) covalently linking an anti-HER2 antibody and an anti-CD3 antibody. The bsAbC showed

We used cryopreserved human hepatocytes that express rapid, intermediate, and slow acetylator N-acetyltransferase 2 (NAT2) genotypes to measure the N-acetylation of β-naphthylamine (BNA) which is one of the aromatic amines found in cigarette smoke including E-cigarettes. We investigated the role of NAT2 genetic polymorphism in genotoxicity and oxidative stress induced by BNA. In vitro BNA NAT2 activities in rapid acetylators was 1.6 and 3.5-fold higher than intermediate (p lt; 0.01) and slow acetylators (p lt; 0.0001). BNA N-acetylation in situ was 3 to 4- fold higher in rapid acetylators than slow acetylators, following incubation with 10 and 100 µM BNA (p lt; 0.01). DNA damage was two to threefold higher in the rapid versus slow acetylators (p lt; 0.0001) and 2.5-fold higher in intermediate versus slow acetylators following BNA treatment at 100 and 1000 μM, ROS/RNS level was the highest in rapid acetylators followed by intermediate and then slow acetylators (p lt; 0.0001). Our findings show that the N-acetylation of BNA is NAT2 genotype dependent in cryopreserved human hepatocytes and our data further document an important role for NAT2 genetic polymorphism in modifying BNA-induced genotoxicity and oxidative damage.

Liver fibrosis results from the formation of fibrous scars of hepatic stellate cells by various chronic liver diseases. Considering that the liver is the most important metabolic organ in the human body, exploring the metabolic characteristics of liver fibrosis is expected to discover new markers and therapeutic targets. In this study, we first used mouse model to verify that both lactate content and histone acetylation levels were significantly increased in hepatic fibrosis mice. At the same time, it was confirmed that activated hepatic stellate cells (HSCs) cocultured with M1 macrophages can promote their transformation into M2 macrophages in hepatic stellate cell line and primary hepatic stellate cells. In addition, the addition of lactic acid to the medium in which M1 cells are cultured can promote their transformation into M2 macrophages. Therefore, we concluded that activated HSCs can promote the transformation of M1 to M2 macrophages through lactate accumulation, thereby causing liver fibrosis.

Studies from both humans and animal models indicated that maternal chronic poor-quality diet, especially a high fat diet (HFD), is significantly associated with reduced bone density and childhood fractures in offspring. When previously studied in a rat model, our data suggested that maternal HFD changes epigenetic marks such as DNA methylation and histone modifications to control osteoblast metabolism. In mouse embryonic and postnatal offspring bone samples, a ChIP-sequencing (ChIP-Seq)-based genome-wide method was used to locate the repressive histone mark H3K27me3 (mediated via the polycomb histone methyltransferase

Vascular smooth muscle cell (VSMC) phenotypic switching contributes to cardiovascular diseases. Epigenetic regulation is emerging as a key regulatory mechanism, with the methylcytosine dioxygenase TET2 acting as a master regulator of smooth muscle cell phenotype. The histone acetyl-transferases p300 and CREB-binding protein (CBP) are highly homologous and often considered to be interchangeable, and their roles in smooth muscle cell phenotypic regulation are not known.We assessed the roles of p300 and CBP in human VSMC with knockdown, in inducible smooth muscle-specific knockout mice (inducible knockout [iKO];P300, CBP, and histone acetylation were differently regulated in VSMCs undergoing phenotypic switching and in vessel remodeling after vascular injury. Medial p300 expression and activity were repressed by injury, but CBP and histone acetylation were induced in neointima. Knockdown experiments revealed opposing effects of p300 and CBP in the VSMC phenotype: p300 promoted contractile protein expression and inhibited migration, but CBP inhibited contractile genes and enhanced migration. p300This work reveals that p300 and CBP serve nonredundant and opposing functions in VSMC phenotypic switching and coordinately regulate chromatin modifications through distinct functional interactions with TET2 or HDACs. Targeting specific histone acetyl-transferases may hold therapeutic promise for cardiovascular diseases.

14 Pág. Centro de Biotecnología y Genómica de Plantas, Chloroplast biogenesis is crucial in plant development, as it is essential for the transition to autotrophic growth. This process is light-induced and relies on the orchestrated transcription of nuclear and plastid genes, enabling the effective assembly and regulation of the photosynthetic machinery. Here we reveal a new regulation level for this process by showing the involvement of chromatin remodelling in the nuclear control of plastid gene expression for proper chloroplast biogenesis and function. The two Arabidopsis homologues of yeast EPL1 protein, components of the NuA4 histone acetyltransferase complex, are essential for plastid transcription and correct chloroplast development and performance. We show that EPL1 proteins are light-regulated and necessary for concerted expression of nuclear genes encoding most components of chloroplast transcriptional machinery, directly mediating H4K5ac deposition at these loci and promoting the expression of plastid genes required for chloroplast biogenesis. These data unveil a NuA4-mediated mechanism regulating chloroplast biogenesis that links the transcription of nuclear and plastid genomes during chloroplast development., This work was funded by the Spanish Ministry of Economy, Industry, and Competitiveness (grant Nos. BIO2016-77559-R and PID2019-104899GB-I00 to M.P. and J.A.J. from MCIN/AEI/10.13039/501100011033 and FEDER; FPI fellowship No. BES-2017-07992 from MCIN/AEI/10.13039/501100011033 and FSE to L.B-M.) and INIA (FPI fellowship No. FPI-SGIT-2016-08 to L.E.-C.). We acknowledge the ‘Severo Ochoa Program for Centres of Excellence in R&D’ from the Agencia Estatal de Investigación of Spain (grant No. SEV-2016-0672 (2017-2021) from MCIN/AEI/10.13039/501100011033) for supporting the scientific services used in this work.

Oxidative stress is the central cause of angiotensin II (Ang II)-induced myocardial injury, and nuclear factor erythroid 2-related factor (Nrf2) is the core molecule of the anti-oxidant defense system. We have previously demonstrated that sulforaphane (SFN) can prevent Ang II-induced myocardial injury by activating Nrf2; however, the underlying molecular mechanism is still unclear. This study aimed to evaluate whether SFN prevents Ang II-induced cardiomyocyte apoptosis through acetylation modification ofiNrf2/i. Wild-type andiNrf2/iknockdown embryonic rat cardiomyocytes (H9C2) were exposed to Ang II to induce apoptosis, oxidative stress, and inflammatory responses. SFN treatment significantly reduced Ang II-induced cardiomyocyte apoptosis, inflammation and oxidative stress. Activation of Nrf2 played a critical role in preventing cardiomyocyte apoptosis. After Nrf2 was knockdown, the anti-inflammatory, antioxidant stress of SFN were eliminated. Furthermore, Nrf2 activation by SFN was closely related to the decreased activity of histone deacetylases (HDACs) and increased histone-3 (H3) acetylation levels iniNrf2/ipromoter region. These findings confirm that Nrf2 plays a key role in SFN preventing Ang II-induced cardiomyocyte apoptosis. SFN activates Nrf2 by inhibiting HDACs expression and activation.

IL-6 is elevated in obese individuals and participates in the metabolic dysfunction associated with that condition. However, the mechanisms that promote IL-6 expression in obesity are incompletely understood. Because elevated levels of palmitate and LPS have been reported in obesity, we investigated whether these agents interact to potentiate IL-6 production. In this study, we report that LPS induces higher levels of IL-6 in human monocytes in the presence of palmitate. Notably, the priming effect of palmitate is associated with enhanced p300 binding and transcription factor recruitment to Il6 promoter regions. Gene silencing of p300 blocks this action of palmitate. RNA polymerase II recruitment was also enhanced at the Il6 promoter in palmitate/LPS-exposed cells. Acetylation levels of H3K9 and H3K18 were increased in monocytes treated with palmitate. Moreover, LPS stimulation of palmitate-treated cells led to increased levels of the transcriptionally permissive acetylation marks H3K9/H3K18 in the Il6 promoter compared with LPS alone. The effect of palmitate on LPS-induced IL-6 production was suppressed by the inhibition of histone acetyltransferases. Conversely, histone deacetylase inhibitors trichostatin A or sodium butyrate can substitute for palmitate in IL-6 production. Esterification of palmitate with CoA was involved, whereas β-oxidation and ceramide biosynthesis were not required, for the induction of IL-6 and H3K9/H3K18 acetylation. Monocytes of obese individuals showed significantly higher H3K9/H3K18 acetylation and Il6 expression. Overall, our findings support a model in which increased levels of palmitate in obesity create a setting for LPS to potentiate IL-6 production via chromatin remodeling, enabling palmitate to contribute to metabolic inflammation.

Endothelial cell senescence is the main risk factor contributing to vascular dysfunction and the progression of aging-related cardiovascular diseases. However, the relationship between endothelial cell metabolism and endothelial senescence remains unclear. The present study provides novel insight into fatty acid metabolism in the regulation of endothelial senescence. In the replicative senescence model and H2O2-induced premature senescence model of primary cultured human umbilical vein endothelial cells (HUVECs), fatty acid oxidation (FAO) was suppressed and fatty acid profile was disturbed, accompanied by downregulation of proteins associated with fatty acid uptake and mitochondrial entry, in particular the FAO rate-limiting enzyme carnitine palmitoyl transferase 1A (CPT1A). Impairment of fatty acid metabolism by silencing CPT1A or CPT1A inhibitor etomoxir facilitated the development of endothelial senescence, as implied by the increase of p53, p21, and senescence-associated β-galactosidase, as well as the decrease of EdU-positive proliferating cells. In the contrary, rescue of FAO by overexpression of CPT1A or supplement of short chain fatty acids (SCFAs) acetate and propionate ameliorated endothelial senescence. In vivo, treatment of acetate for 4 weeks lowered the blood pressure and alleviated the senescence-related phenotypes in aortas of Ang II-infused mice. Mechanistically, fatty acid metabolism regulates endothelial senescence via acetyl-coenzyme A (acetyl-CoA), as implied by the observations that suppression of acetyl-CoA production using the inhibitor of ATP citrate lyase NDI-091143 accelerated senescence of HUVECs and that supplementation of acetyl-CoA prevented H2O2-induced endothelial senescence. Deficiency of acetyl-CoA resulted in alteration of acetylated protein profiles which are associated with cell metabolism and cell cycle. These findings thus suggest that improvement of fatty acid metabolism might ameliorate endothelial senescence-associated cardiovascular diseases.

The dihydrolipoamide acetyltransferase subunit DLA2 of the chloroplast pyruvate dehydrogenase complex (cpPDC) in the green alga Chlamydomonas reinhardtii has previously been shown to possess moonlighting activity in chloroplast gene expression. Under mixotrophic growth conditions, DLA2 forms part of a ribonucleoprotein particle (RNP) with the psbA mRNA that encodes the D1 protein of the photosystem II (PSII) reaction center. Here, we report on the characterization of the molecular switch that regulates shuttling of DLA2 between its functions in carbon metabolism and D1 synthesis. Determination of RNA-binding affinities by microscale thermophoresis demonstrated that the E3-binding domain (E3BD) of DLA2 mediates psbA-specific RNA recognition. Analyses of cpPDC formation and activity, as well as RNP complex formation, showed that acetylation of a single lysine residue (K197) in E3BD induces the release of DLA2 from the cpPDC, and its functional shift towards RNA binding. Moreover, Förster resonance energy transfer microscopy revealed that psbA mRNA/DLA2 complexes localize around the chloroplast's pyrenoid. Pulse labeling and D1 re-accumulation after induced PSII degradation strongly suggest that DLA2 is important for D1 synthesis during de novo PSII biogenesis.

Since epigenetic regulation seemed likely to be involved in SV40 early transcription following infection, we have analyzed the organization of nucleosomes carrying histone modifications (acetyl-H3, acetyl-H4, H3K9me1, H3K9me3, H3K4me1, H3K4me3, H3K27me3, H4K20me1) at 30 min and 2 h post infection in SV40 minichromosomes prepared in the absence or presence of the transcription inhibitor dichloro-1-beta-d-ribofuranosyl benzimidazole. The former condition was used to determine how SV40 chromatin structure changed during early transcription, and the latter was used to determine the role of active transcription. The location of RNAPII was used as a marker to identify where histone modifications were most likely to be involved in regulation. Acetyl-H3 acted like epigenetic memory by being present at sites subsequently bound by RNAPII, while H3K9me1 and H3K27me3 were reorganized to the late side of the SV40 regulatory region apparently to repress late transcription. The organization of acetyl-H3 and H3K9me1 but not H3K27me3 required active transcription.

Epigenetic changes associated with histone modifications play an important role in the emergence and maintenance of the phenotype of various cancer types. In contrast to direct mutations in the main DNA sequence, these changes are reversible, which makes the development of inhibitors of enzymes of post-translational histone modifications one of the most promising strategies for the creation of anticancer drugs. To date, a wide variety of histone modifications have been found that play an important role in the regulation of chromatin state, gene expression, and other nuclear events. This review examines the main features of the most common and studied epigenetic histone modifications with a proven role in the pathogenesis of a wide range of malignant neoplasms: acetylation / deacetylation and methylation / demethylation of histone proteins, as well as the role of enzymes of the HAT / HDAC and HMT / HDMT families in the development of oncological pathologies. The data on the relationship between histone modifications and certain types of cancer are presented and discussed. Special attention is devoted to the consideration of various strategies for the development of epigenetic inhibitors. The main directions of the development of inhibitors of histone modifications are analyzed and effective strategies for their creation are identified and discussed. The most promising strategy is the use of multitarget drugs, which will affect multiple molecular targets of cancer. A critical analysis of the current status of approved epigenetic anticancer drugs has also been performed.

FACT (FAcilitates Chromatin Transcription) is a heterodimeric protein complex composed of SUPT16H and SSRP1, and a histone chaperone participating in chromatin remodeling during gene transcription. FACT complex is profoundly regulated, and contributes to both gene activation and suppression. Here we reported that SUPT16H, a subunit of FACT, is acetylated in both epithelial and natural killer (NK) cells. The histone acetyltransferase TIP60 contributes to the acetylation of SUPT16H middle domain (MD) at lysine 674 (K674). Such acetylation of SUPT16H is recognized by bromodomain protein BRD4, which promotes protein stability of SUPT16H in both epithelial and NK cells. We further demonstrated that SUPT16H-BRD4 associates with histone modification enzymes (HDAC1, EZH2), and further regulates their activation status and/or promoter association as well as affects the relevant histone marks (H3ac, H3K9me3 and H3K27me3). BRD4 is known to profoundly regulate interferon (IFN) signaling, while such function of SUPT16H has never been explored. Surprisingly, our results revealed that SUPT16H genetic knockdown via RNAi or pharmacological inhibition by using its inhibitor, curaxin 137 (CBL0137), results in the induction of IFNs and interferon-stimulated genes (ISGs). Through this mechanism, depletion or inhibition of SUPT16H is shown to efficiently inhibit infection of multiple viruses, including Zika, influenza, and SARS-CoV-2. Furthermore, we demonstrated that depletion or inhibition of SUPT16H also causes the remarkable activation of IFN signaling in NK cells, which promotes the NK-mediated killing of virus-infected cells in a co-culture system using human primary NK cells. Overall, our studies unraveled the previously un-appreciated role of FACT complex in coordinating with BRD4 and regulating IFN signaling in both epithelial and NK cells, and also proposed the novel application of the FACT inhibitor CBL0137 to treat viral infections.

Increased frequency of DNA double strand breaks (DSBs) with aging suggests an age-associated decline in DSB repair efficiency, which is also influenced by the epigenetic landscape. H4 acetylation at lysine 16 (H4K16Ac) has been related to DSB repair since deacetylation of this mark is required for efficient 53BP1 recruitment to DSBs. Although age-associated changes in H4K16Ac levels have been studied, their contribution to age-related DSB accumulation remains unknown. In vitro aged Human Dermal Fibroblasts (HDFs) display lower levels of H4K16A that correlate with reduced recruitment of 53BP1 to basal DSBs. Following DNA damage induction, early passage (EP) cells suffered from a transient H4K16 deacetylation that allowed proper 53BP1 recruitment to DSBs. In contrast, to reach this specific and optimum level, aged cells responded by increasing their overall lower H4K16Ac levels. Induced hyperacetylation of late passage (LP) cells using trichostatin A increased H4K16Ac levels but did not ameliorate 53BP1 recruitment. Instead, deacetylation induced by MOF silencing reduced H4K16Ac levels and compromised 53BP1 recruitment in both EP and LP cells. Age-associated decrease of H4K16Ac levels contributes to the repair defect displayed by in vitro aged cells. H4K16Ac responds to DNA damage in order to reach a specific, optimum level that allows proper 53BP1 recruitment. This response may be compromised with age, as LP cells depart from lower H4K16Ac levels. Variations in H4K16Ac following the activation of the DNA damage response and aging point at this histone mark as a key mediator between DNA repair and age-associated chromatin alterations.

Accurate prediction of post-translational modifications (PTMs) is of great significance in understanding cellular processes, by modulating protein structure and dynamics. Nowadays, with the rapid growth of protein data at different "omics" levels, machine learning models largely enriched the prediction of PTMs. However, most machine learning models only rely on protein sequence and little structural information. The lack of the systematic dynamics analysis underlying PTMs largely limits the PTM functional predictions. In this research, we present two dynamics-centric deep learning models, namely, cDL-PAU and cDL-FuncPhos, by incorporating sequence, structure, and dynamics-based features to elucidate the molecular basis and underlying functional landscape of PTMs. cDL-PAU achieved satisfactory area under the curve (AUC) scores of 0.804-0.888 for predicting phosphorylation, acetylation, and ubiquitination (PAU) sites, while cDL-FuncPhos achieved an AUC value of 0.771 for predicting functional phosphorylation (FuncPhos) sites, displaying reliable improvements. Through a feature selection, the dynamics-based coupling and commute ability show large contributions in discovering PAU sites and FuncPhos sites, suggesting the allosteric propensity for important PTMs. The application of cDL-FuncPhos in three oncoproteins not only corroborates its strong performance in FuncPhos prioritization but also gains insight into the physical basis for the functions. The source code and data set of cDL-PAU and cDL-FuncPhos are available at https://github.com/ComputeSuda/PTM_ML.

Major depressive disorder (MDD) is a disease associated with many factors; specifically, environmental, genetic, psychological, and biological factors play critical roles. Recent studies have demonstrated that histone modification may occur in the human brain in response to severely stressful events, resulting in transcriptional changes and the development of MDD. In this review, we discuss five different histone modifications, histone methylation, histone acetylation, histone phosphorylation, histone crotonylation and histone β-hydroxybutyrylation, and their relationships with MDD. The utility of histone deacetylase (HDAC) inhibitors (HDACis) for MDD treatment is also discussed. As a large number of MDD patients in China have been treated with traditional Chineses medicine (TCM), we also discuss some TCM therapies, such as Xiaoyaosan (XYS), and their effects on histone modification. In summary, targeting histone modification may be a new strategy for elucidating the mechanism of MDD and a new direction for MDD treatment.

Ewing sarcoma breakpoint region 1 (EWSR1) is a member of FET (FUS/EWSR1/TAF15) RNA-binding family of proteins. The Ewing sarcoma oncoprotein EWS-FLI1 has been extensively studied, while much less is known about EWSR1 itself, especially the potential role of EWSR1 in response to DNA damage. Here, we found that UV irradiation induces acetylation of EWSR1, which is required for its nucleoli translocation. We identified K423, K432, K438, K640, and K643 as the major acetylation sites, p300/CBP and HDAC3/HDAC10 as the major acetyltransferases and deacetylases, respectively. Mechanically, UV-induced EWSR1 acetylation repressed its interaction with spliceosomal component U1C, which caused abnormal splicing of CHK2, suppressing the activity of CHK2 in response to UV irradiation. Taken together, our findings uncover acetylation as a novel regulatory modification of EWSR1, and is essential for its function in DNA damage response.

Poaceae plants can locally accumulate iron to suppress pathogen infection. It remains unknown how pathogens overcome host-derived iron stress during their successful infections. Here, we report that Fusarium graminearum (Fg), a destructive fungal pathogen of cereal crops, is challenged by host-derived high-iron stress. Fg infection induces host alkalinization, and the pH-dependent transcription factor FgPacC undergoes a proteolytic cleavage into the functional isoform named FgPacC30 under alkaline host environment. Subsequently FgPacC30 binds to a GCCAR(R = A/G)G element at the promoters of the genes involved in iron uptake and inhibits their expression, leading to adaption of Fg to high-iron stress. Mechanistically, FgPacC30 binds to FgGcn5 protein, a catalytic subunit of Spt-Ada-Gcn5 Acetyltransferase (SAGA) complex, leading to deregulation of histone acetylation at H3K18 and H2BK11, and repression of iron uptake genes. Moreover, we identified a protein kinase FgHal4, which is highly induced by extracellular high-iron stress and protects FgPacC30 against 26S proteasome-dependent degradation by promoting FgPacC30 phosphorylation at Ser2. Collectively, this study uncovers a novel inhibitory mechanism of the SAGA complex by a transcription factor that enables a fungal pathogen to adapt to dynamic microenvironments during infection.

To detect the epigenetic drift of time passing, we determined the genome-wide distributions of mono- and tri-methylated lysine 4 and acetylated and tri-methylated lysine 27 of histone H3 in the livers of healthy 3, 6 and 12 months old C57BL/6 mice. The comparison of different age profiles of histone H3 marks revealed global redistribution of histone H3 modifications with time, in particular in intergenic regions and near transcription start sites, as well as altered correlation between the profiles of different histone modifications. Moreover, feeding mice with caloric restriction diet, a treatment known to retard aging, reduced the extent of changes occurring during the first year of life in these genomic regions.

Canine hemangiosarcoma (HSA) is a malignant tumour derived from endothelial cells. No effective treatment has yet been developed because of the lack of understanding of its pathogenesis. Histone acetylation, an epigenetic modification, is highly associated with cancer pathogenesis. Manipulating histone acetylation by histone deacetylase inhibitors (HDACi) or bromodomain and extraterminal domain inhibitors (BETi) is one approach to treat various cancers. However, the role of histone acetylation in HSA remains unknown. This study aimed to investigate how histone acetylation functions in HSA pathogenesis using two HDACi, suberanilohydroxamic acid (SAHA) and valproic acid (VPA), and one BETi, JQ1, in vitro and in vivo. Histone acetylation levels were high in cell lines and heterogeneous in clinical cases. SAHA and JQ1 induced apoptosis in HSA cell lines. HSA cell lines treated with SAHA and VPA upregulated inflammatory-related genes and attracted macrophage cell line RAW264 cells, which suggests that SAHA and VPA can affect immune responses. JQ1 stimulated autophagy and inhibited the cell cycle in HSA cell lines. Finally, we demonstrated that JQ1 suppressed HSA tumour cell proliferation in vivo although SAHA and VPA did not affect tumour growth. These results suggest that BETi can be alternative drugs for HSA treatment. Although further research is required, our study indicated that dysregulation of histone acetylation is likely to be involved in HSA malignancy.

A new study employs CRISPR/Cas9-based base editing for simultaneous mutagenesis of all copies of histone H3 genes in mammals, highlighting the functional importance of H3K27me3 for Polycomb-mediated gene silencing and the dispensability for H3K27ac in transcriptional activation.

A modest autophagy benefits neuroprotection while an excessive autophagy leads to neuronal death after cerebral ischemia, but what governs an appropriate autophagy remains to be understood. Studies indicated that acetylation of histone H4 at lysine16 (H4K16ac) strongly modulated autophagic/lysosomal signaling pathway. Thus, this study was to investigate whether the autophagic neuronal injury could be alleviated by amending H4K16ac level after ischemic stroke. A rat model of middle cerebral artery occlusion (MCAO)/reperfusion was prepared to investigate dynamic variations between H4K16ac and autophagy at the penumbra. The results illustrated that the significantly elevated H4K16ac was coupled with dramatically promoted autophagic activity at 4 h after the insult, suggesting H4K16ac tightly controlled autophagic signaling. After that, H4K16ac level was altered by pretreatment with trichostatin A (TSA, a H4K16ac facilitator) and MG149 (a H4K16ac inhibitor), respectively. Four hours after MCAO/reperfusion, the penumbral tissues were obtained to detect the key proteins in autophagic/lysosomal pathway by western blot and immunofluorescence, respectively. Meanwhile, the infarct volume, neurological deficits, and neuron survival were assessed to evaluate the neurological outcomes. The results showed that TSA-promoted H4K16ac led to an excessively up-regulated autophagy resulting in autophagic/lysosomal dysfunction, as indicated by the accumulated autophagic substrates and exacerbated lysosomal inefficiency in neurons. By contrast, MG149-depressed H4K16ac significantly down-regulated autophagic activity and thereby restored the impaired autophagic flux. Consequently, the neurological injury was markedly alleviated in MCAO + MG149 group, compared with that in MCAO group. Our study suggests that the H4K16ac attenuation elicits neuroprotection against ischemic stroke by ameliorating autophagic/lysosomal dysfunction in neurons.

The number of acetylated proteins identified from bacteria to mammals has grown exponentially in the last ten years, and it is now accepted that acetylation is a key component in most eukaryotic signaling pathways and is as important as phosphorylation. The enzymes involved in this process are well described in mammals; acetyltransferases and deacetylases are found inside and outside the nuclear compartment and have different regulatory functions. In trypanosomatids, several of these enzymes have been described and are postulated to be novel antiparasitic targets for the rational design of drugs. In this review article, we present an update of the most important known acetylated proteins in trypanosomatids, analyzing the acetylomes available. Also, we summarize the information available regarding acetyltransferases and deacetylases in trypanosomes and their potential use as chemotherapeutic targets.

Lysine acetylation is a reversible post-translational modification (PTM) involved in multiple physiological functions. Recent studies have demonstrated the involvement of protein acetylation in modulating the biology of Schwann cells (SCs) and regeneration of the peripheral nervous system (PNS). However, the mechanisms underlying these processes remain partially understood. Here, we characterized the acetylome of the mouse sciatic nerve (SN) and investigated the cellular distribution of acetylated proteins. We identified 483 acetylated proteins containing 1442 acetylation modification sites in the SN of adult C57BL/6 mice. Bioinformatics suggested that these acetylated SN proteins were mainly located in the myelin sheath, mitochondrial inner membrane, and cytoskeleton, and highlighted the significant differences between the mouse SN and brain acetylome. Manual annotation further indicated that most acetylated proteins ( 45%) were associated with mitochondria, energy metabolism, and cytoskeleton and cell adhesion. We verified three newly discovered acetylation-modified proteins, including neurofilament light polypeptide (NEFL), neurofilament medium/high polypeptide (NFM/H), and periaxin (PRX). Immunofluorescence illustrated that the acetylated proteins, including acetylated alpha-tubulin, were mainly co-localized with S100-positive SCs. Herein, we provided a comprehensive acetylome for the mouse SN and demonstrated that acetylated proteins in the SN were predominantly located in SCs. These results will extend our understanding and promote further study of the role and mechanism of protein acetylation in SC development and PNS regeneration.

The optimization of the parameters involved in lignin extraction is crucial for obtaining a lignin with specific structural features for its further valorization. The aim of this work was to develop an eco-friendly organosolv protocol for tuning the acetylation degree of coconut shell lignins (CSLs) by using MgCl

The negative effects of low temperature can readily induce a variety of diseases. We sought to understand the reasons why cold stress induces disease by studying the mechanisms of fine-tuning in macrophages following cold exposure. We found that cold stress triggers increased macrophage activation accompanied by metabolic reprogramming of aerobic glycolysis. The discovery, by genome-wide RNA sequencing, of defective mitochondria in mice macrophages following cold exposure indicated that mitochondrial defects may contribute to this process. In addition, changes in metabolism drive the differentiation of macrophages by affecting histone modifications. Finally, we showed that histone acetylation and lactylation are modulators of macrophage differentiation following cold exposure. Collectively, metabolism-related epigenetic modifications are essential for the differentiation of macrophages in cold-stressed mice, and the regulation of metabolism may be crucial for alleviating the harm induced by cold stress.

The steady-state level of histone acetylation is maintained by histone acetyltransferase (HAT) and histone deacetylase (HDAC) complexes. INhibitor of Growth (ING) proteins are key components of the HAT or HDAC complexes but their relationship with other components and roles in phytopathogenic fungi are not well-characterized. Here, the FNG3 ING gene was functionally characterized in the wheat head blight fungus Fusarium graminearum. Deletion of FNG3 results in defects in fungal development and pathogenesis. Unlike other ING proteins that are specifically associated with distinct complexes, Fng3 was associated with both NuA3 HAT and FgRpd3 HDAC complexes to regulate H3 acetylation and H4 deacetylation. Whereas FgNto1 mediates the FgSas3-Fng3 interaction in the NuA3 complex, Fng3 interacted with the C-terminal region of FgRpd3 that is present in Rpd3 orthologs from filamentous fungi but absent in yeast Rpd3. The intrinsically disordered regions in the C-terminal tail of FgRpd3 underwent phase separation, which was important for its interaction with Fng3. Furthermore, the ING domain of Fng3 is responsible for its specificities in protein-protein interactions and functions. Taken together, Fng3 is involved in the dynamic regulation of histone acetylation by interacting with two histone modification complexes, and is important for fungal development and pathogenicity.

The evolutionarily conserved cohesin complex mediates sister chromatid cohesion and facilitates mitotic chromosome condensation, DNA repair, and transcription regulation. These biological functions require cohesin's two ATPases, formed by the Smc1p and Smc3p subunits. Cohesin's ATPase activity is stimulated by the Scc2p auxiliary factor. This stimulation is inhibited by Eco1p acetylation of Smc3p at an interface with Scc2p. It was unclear how cohesin's ATPase activity is stimulated by Scc2p or how acetylation inhibits Scc2p, given that the acetylation site is distal to cohesin's ATPase active sites. Here, we identify mutations in budding yeast that suppressed the in vivo defects caused by Smc3p acetyl-mimic and acetyl-defective mutations. We provide compelling evidence that Scc2p activation of cohesin ATPase depends on an interface between Scc2p and a region of Smc1p proximal to cohesin's Smc3p ATPase active site. Furthermore, substitutions at this interface increase or decrease ATPase activity to overcome ATPase modulation by acetyl-mimic and acetyl-null mutations. Using these observations and an existing cryo-EM structure, we propose a model for regulating cohesin ATPase activity. We suggest that Scc2p binding to Smc1p causes the adjacent Smc1p residues and ATP to shift, stimulating Smc3p's ATPase. This stimulatory shift is inhibited through acetylation of the distal Scc2p–Smc3p interface.

DNA replication perturbs chromatin by triggering the eviction, replacement, and incorporation of nucleosomes. How this dynamic is orchestrated in time and space is poorly understood. Here, we apply a genetically encoded sensor for histone exchange to follow the time-resolved histone H3 exchange profile in budding yeast cells undergoing slow synchronous replication in nucleotide-limiting conditions. We find that new histones are incorporated not only behind, but also ahead of the replication fork. We provide evidence that Rtt109, the S-phase-induced acetyltransferase, stabilizes nucleosomes behind the fork but promotes H3 replacement ahead of the fork. Increased replacement ahead of the fork is independent of the primary Rtt109 acetylation target H3K56 and rather results from Vps75-dependent Rtt109 activity toward the H3 N terminus. Our results suggest that, at least under nucleotide-limiting conditions, selective incorporation of differentially modified H3s behind and ahead of the replication fork results in opposing effects on histone exchange, likely reflecting the distinct challenges for genome stability at these different regions.

Histone acetylation may affect the tumorigenesis and prognosis of colorectal cancer (CRC). However, there is still a lack of studies exploring the effect of acetylation-related genes on the prognosis of CRC. To explore the role of acetylation-related genes in CRC prognosis using bioinformatics strategies, the expression data and survival information of CRC patients were collected from the Gene Expression Omnibus. The Molecular Signatures Database was used to select acetylation-related genes. Univariate and least absolute shrinkage and selection operator regression analyses were used to screen prognostic genes. Kaplan-Meier curves were plotted for survival analysis. Cibersort and pRRophetics were used to analyze immune infiltration and predict drug sensitivity, respectively. By implementing independent prognostic factors, a nomogram model was constructed. The result showed that a total of 48 prognostic genes which screened from the acetylation-related gene set were mainly enriched in ABC transporters and acetylation/deacetylation-related pathways. Three gene signatures (SDR16C5, MEAF6, and SOX4) were further defined, and a prognostic model was constructed that showed high sensitivity and specificity for predicting CRC prognosis in both training and validation cohorts. Patients with different prognostic risks also presented differential expression of gene signatures, infiltration of activated CD4 memory T cells, and drug sensitivity to bicalutamide, gefitinib, Lenalidomide, and imatinib. The nomogram suggested the potential of a risk score-based model in predicting 1- and 2-year survival in patients with CRC. In conclusion, we proposed three gene signatures from an acetylation-related gene set as potential targets for epigenetic therapy and constructed a prognostic model for CRC.

Lysine acetyltransferase 2 A (KAT2A) has been implicated in tumorigenesis; nevertheless, the mechanism underlying its tumor-initiating effect remains elusive. In the present study, we aimed to identify the possible role of KAT2A in regulating metabolic reprogramming, a hallmark of cancer, in colon cancer (CC). KAT2A was found to be overexpressed in CC and correlated with metastases. KAT2A induced proliferation, migration, invasion, and epithelial-mesenchymal transition of CC cells, along with elevated cellular glycolytic capacity and mitochondrial stress. Functional enrichment analyses predicted and ChIP assays verified that KAT2A activated E2F transcription factor 1 (E2F1) by modifying the acetylation of H3K9. Rescue experiments revealed that E2F1 downregulation inhibited cellular activity, aerobic glycolysis and mitochondrial respiration in CC in the presence of KAT2A. Moreover, KAT2A/E2F1 promoted tumorigenic activity and lung metastases of CC cells in mice. Taken together, our findings demonstrate the substantial role of KAT2A in the modulation of post-translational modifications of E2F1 in CC, suggesting that knockdown of KAT2A may be a potential strategy for CC treatment.

Reversible lysine acetylation regulates the activity of cardiac metabolic enzymes, including those controlling fuel substrate metabolism. Mitochondrial-targeted GCN5L1 and SIRT3 have been shown to regulate the acetylation status of mitochondrial enzymes, but the role that lysine acetylation plays in driving metabolic differences between male and female hearts is not currently known. In this study, we describe a significant difference in GCN5L1 levels between male and female mouse hearts, and in the hearts of women between post- and premenopausal age. We further find that estrogen drives GCN5L1 expression in a cardiac cell line and uses pharmacological approaches to determine the mechanism to be G protein-coupled estrogen receptor (GPER) activation, via translational regulation. NEW & NOTEWORTHY We demonstrate here for the first time that mitochondrial protein acetylation is increased in female hearts, associated with an increase in GCN5L1 levels through a GPER-dependent mechanism. These findings reveal a new potential mediator of divergent cardiac mitochondrial function between men and women.

Although it is well-established that p53-mediated tumor suppression mainly acts through its ability in transcriptional regulation, the molecular mechanisms of this regulation are not completely understood. Among a number of regulatory modes, acetylation of p53 attracts great interests. p53 was one of the first non-histone proteins found to be functionally regulated by acetylation and deacetylation, and subsequent work has established that reversible acetylation is a general mechanism for regulation of non-histone proteins. Unlike other types of posttranslational modifications occurred during stress responses, the role of p53 acetylation has been recently validated in vivo by using the knock-in mice with both acetylation-defective and acetylation-mimicking p53 mutants. Here, we review the role of acetylation in p53-mediated activities, with a focus on which specific acetylation sites are critical for p53-dependent transcription regulation during tumor suppression and how acetylation of p53 recruits specific "readers" to execute its promoter-specific regulation of different targets. We also discuss the role of p53 acetylation in differentially regulating its classic activities in cell cycle arrest, senescence and apoptosis as well as newly identified unconventional functions such as cell metabolism and ferroptosis.

Recent studies have identified cancer-associated mutations in histone genes that lead to the expression of mutant versions of core histones called oncohistones. Many oncohistone mutations occur at Asp and Glu residues, two amino acids known to be ADP-ribosylated (ADPRylated) by PARP1. We screened 25 Glu or Asp oncohistone mutants for their effects on cell growth in breast and ovarian cancer cells. Ectopic expression of six mutants of three different core histones (H2B, H3, and H4) altered cell growth in at least two different cell lines. Two of these sites, H2B-D51 and H4-D68, were indeed sites of ADPRylation in wild-type (unmutated) histones, and mutation of these sites inhibited ADPRylation. Mutation of H2B-D51 dramatically altered chromatin accessibility at enhancers and promoters, as well as gene expression outcomes, whereas mutation of H4-D68 did not. Additional biochemical, cellular, proteomic, and genomic analyses demonstrated that ADPRylation of H2B-D51 inhibits p300-mediated acetylation of H2B at many Lys residues. In breast cancer cell xenografts in mice, H2B-D51A promoted tumor growth, but did not confer resistance to the cytotoxic effects of PARP inhibition. Collectively, these results demonstrate that functional Asp and Glu ADPRylation sites on histones are mutated in cancers, allowing cancer cells to escape the growth-regulating effects of post-translational modifications via distinct mechanisms. Significance: This study identifies cancer-driving mutations in histones as sites of PARP1–mediated ADP-ribosylation in breast and ovarian cancers, providing a molecular pathway by which cancers may subvert the growth-regulating effects of PARP1.

The family of lysine acetyltransferases (KATs) regulates epigenetics and signaling pathways in eukaryotic cells. So far, knowledge of different KAT members contributing to the cellular acetylome is limited, which limits our understanding of biological functions of KATs in physiology and disease. Here, we found that a clickable acyl-CoA reporter, 3-azidopropanoyl CoA (3AZ-CoA), presented remarkable cell permeability and effectively acylated proteins in cells. We rationally engineered the major KAT member, histone acetyltransferase 1 (HAT1), to generate its mutant forms that displayed excellent bio-orthogonal activity for 3AZ-CoA in substrate labeling. We were able to apply the bio-orthogonal enzyme-cofactor pair combined with SILAC proteomics to achieve HAT1 substrate targeting, enrichment, and proteomic profiling in living cells. A total of 123 protein substrates of HAT1 were disclosed, underlining the multifactorial functions of this important enzyme than hitherto known. This study demonstrates the first example of utilizing bio-orthogonal reporters as a chemoproteomic strategy for substrate mapping of individual KAT isoforms in the native biological contexts.

Osmotic stress caused by drought and high salinity is a significant environmental threat that limits plant growth and agricultural yield. Redox regulation plays an important role in plant stress responses, but the mechanisms by which plants perceive and transduce redox signals are still underexplored. Here, we report a critical function for the thiol peroxidase GPX1 in osmotic stress response in rice, where it serves as a redox sensor and transducer. GPX1 is quickly oxidized upon exposure to osmotic stress and forms an intramolecular disulfide bond, which is required for the activation of bZIP68, a VRE-like basic leucine zipper (bZIP) transcription factor involved in the ABA-independent osmotic stress response pathway. The disulfide exchange between GPX1 and bZIP68 induces homo-tetramerization of bZIP68 and thus positively regulates osmotic stress response by regulating osmotic-responsive gene expression. Furthermore, we discovered that the nuclear translocation of GPX1 is regulated by its acetylation under osmotic stress. Taken together, our findings not only uncover the redox regulation of the GPX1-bZIP68 module during osmotic stress but also highlight the coordination of protein acetylation and redox signaling in plant osmotic stress responses.

Histone acetylation balance is one epigenetic mechanism controlling gene expression associated with disease progression. It has been observed that histone deacetylase 10 (HDAC-10) isozyme contributes to the chemotherapy resistance; in addition, the poor clinical outcome observed in patients with aggressive solid tumors, such as neuroblastoma, has been associated with its overexpression. Moreover, HDAC-10 selective inhibition suppresses the autophagic response, thus providing an improved risk-benefit profile compared to cytotoxic cancer chemotherapy drugs. On these bases, HDAC-10 is becoming an emerging target for drug design. Due to the rapid progress in the development of next-generation HDAC inhibitors, this review article aims to provide an overview on novel selective or dual HDAC-8/10 inhibitors, as new leads for cancer chemotherapy, able to avoid the severe side-effects of several actual approved “pan” HDAC inhibitors. A literature search was conducted in MedLine, PubMed, Caplus, SciFinder Scholar databases from 2015 to the present. Since the disclosure that the HDAC-6 inhibitor Tubastatin A was able to bind HDAC-10 efficiently, several related analogues were synthesized and tested. Both tricyclic (25-30) and bicyclic (31-42) derivatives were considered. The best pharmacological profile was shown by 36 (HDAC-10 pIC50 = 8.4 and pIC50 towards Class I HDACs from 5.2–6.4). In parallel, based on the evidence that high levels of HDAC-8 are a marker of poor prognosis in neuroblastoma treatment, dual HDAC-8/10 inhibitors were designed. The hydroxamic acid TH34 (HDAC-8 and 10 IC50 = 1.9 µM and 7.7 µM, respectively) and the hybrid derivatives 46d, 46e and 46g were the most promising both in terms of potency and selectivity. Literature surveys indicate several structural requirements for inhibitory potency and selectivity towards HDAC-10, e.g., electrostatic and/or hydrogen bond interactions with E274 and complementarity to the P(E,A) CE motif helix.

Epigenetic regulations play a crucial role in the expression of various genes that are important in the normal cell function. Any alteration in these epigenetic mechanisms can lead to the modification of histone and DNA, resulting in the silencing or enhanced expression of some genes causing various diseases. Acetylation, methylation, ribosylation, or phosphorylation of histone proteins modifies its interaction with the DNA, consequently changing the ratio of heterochromatin and euchromatin. Terminal lysine residues of histone proteins serve as potential targets of such epigenetic modifications. The current review focuses on the histone modifications, and their contributing factors; the role of these modifications on metabolism leads to cancer, and methylation of histone in cancer affects the DNA repair mechanisms.

There is a close connection between epigenetic regulation, cancer metabolism, and immunology. The combination of epigenetic therapy and immunotherapy provides a promising avenue for cancer management. As an epigenetic regulator of histone acetylation, panobinostat can induce histone acetylation and inhibit tumor cell proliferation, as well as regulate aerobic glycolysis and reprogram intratumoral immune cells. JQ1 is a BRD4 inhibitor that can suppress PD-L1 expression. Herein, we proposed a chemo-free, epigenetic-based combination therapy of panobinostat/JQ1 for metastatic colorectal cancer. A novel targeted binary-drug liposome was developed based on lactoferrin-mediated binding with the LRP-1 receptor. It was found that the tumor-targeted delivery was further enhanced by in situ formation of albumin corona. The lactoferrin modification and endogenous albumin adsorption contribute a dual-targeting effect on the receptors of both LRP-1 and SPARC that were overexpressed in tumor cells and immune cells (e.g., tumor-associated macrophages). The targeted liposomal therapy was effective to suppress the crosstalk between tumor metabolism and immune evasion via glycolysis inhibition and immune normalization. Consequently, lactic acid production was reduced and angiogenesis inhibited; TAM switched to an anti-tumor phenotype, and the anti-tumor function of the effector CD8+ T cells was reinforced. The strategy provides a potential method for remodeling the tumor immune microenvironment (TIME).

Chaperones influence histone conformation and intermolecular interaction in multiprotein complexes, and the structures obtained with full-length histones often provide more accurate and comprehensive views. Here, our structure of the Hat1–Hat2 acetyltransferase complex bound to Asf1–H3–H4 shows that the core domains of H3 and H4 are involved in binding Hat1 and Hat2, and the N-terminal tail of H3 makes extensive interaction with Hat2. These findings expand the knowledge about histone–protein interaction and implicate a function of Hat2/RbAp46/48, which is a versatile histone chaperone found in many chromatin-associated complexes, in the passing of histones between chaperones.