Histone Acetylation Levels Research Articles

Unique and Shared Roles for Histone H3K36 Methylation States in Transcription Regulation Functions

Set2 co-transcriptionally methylates lysine 36 of histone H3 (H3K36), producing mono-, di-, and trimethylation (H3K36me1/2/3). These modifications recruit or repel chromatin effector proteins important for transcriptional fidelity, mRNA splicing, and DNA repair. However, it was not known whether the different methylation states of H3K36 have distinct biological functions. Here, we use engineered forms of Set2 that produce different lysine methylation states to identify unique and shared functions for H3K36 modifications. Although H3K36me1/2 and H3K36me3 are functionally redundant in many SET2 deletion phenotypes, we found that H3K36me3 has a unique function related to Bur1 kinase activity and FACT (facilitates chromatin transcription) complex function. Further, during nutrient stress, either H3K36me1/2 or H3K36me3 represses high levels of histone acetylation and cryptic transcription that arises from within genes. Our findings uncover the potential for the regulation of diverse chromatin functions by different H3K36 methylation states.

Improvements on the quantitative analysis of Trypanosoma cruzi histone post translational modifications: Study of changes in epigenetic marks through the parasite's metacyclogenesis and life cycle

Trypanosome histone N-terminal sequences are very divergent from the other eukaryotes, although they are still decorated by post-translational modifications (PTMs). Here, we used a highly robust workflow to analyze histone PTMs in the parasite Trypanosoma cruzi using mass spectrometry-based (MS-based) data-independent acquisition (DIA). We adapted the workflow for the analysis of the parasite's histone sequences by modifying the software EpiProfile 2.0, improving peptide and PTM quantification accuracy. This workflow could now be applied to the study of 141 T. cruzi modified histone peptides, which we used to investigate the dynamics of histone PTMs along the metacyclogenesis and the life cycle of T. cruzi. Global levels of histone acetylation and methylation fluctuates along metacyclogenesis, however most critical differences were observed between parasite life forms. More than 66 histone PTM changes were detected. Strikingly, the histone PTM pattern of metacyclic trypomastigotes is more similar to epimastigotes than to cellular trypomastigotes. Finally, we highlighted changes at the H4 N-terminus and at H3K76 discussing their impact on the trypanosome biology. Altogether, we have optimized a workflow easily applicable to the analysis of histone PTMs in T. cruzi and generated a dataset that may shed lights on the role of chromatin modifications in this parasite. SignificanceTrypanosomes are unicellular parasites that have divergent histone sequences, no chromosome condensation and a peculiar genome/gene regulation. Genes are transcribed from divergent polycistronic regions and post-transcriptional gene regulation play major role on the establishment of transcripts and protein levels. In this regard, the fact that their histones are decorated with multiple PTMs raises interesting questions about their role. Besides, this digenetic organism must adapt to different environments changing its metabolism accordingly. As metabolism and epigenetics are closely related, the study of histone PTMs in trypanosomes may enlighten this strikingly, and not yet fully understood, interplay. From a biomedical perspective, the comprehensive study of molecular mechanisms associated to the metacyclogenesis process is essential to create better strategies for controlling Chagas disease.

Effects of PM2.5 exposure in utero on heart injury, histone acetylation and GATA4 expression in offspring mice

Atmospheric fine particulate matter exposure (PM2.5) can increase the incidence and mortality of heart disease, and raise the risk of fetal congenital heart defect, which have recently drawn much attention. In this study, C57BL/6 mice were exposed to PM2.5 (approximately equivalent to 174 μg/m3) by intratracheal instillation during the gestation. After birth, 10 weeks old offspring mice were divided into four groups: male exposed group (ME), female exposed group (FE), male control group (MC), female control group (FC). The pathological injury, pro-inflammatory cytokines, histone acetylation levels, and expressions of GATA-binding protein 4 (GATA4) and downstream genes were investigated. The results showed that exposure to PM2.5 in utero increased pathological damage and TNF-α and IL-6 levels in hearts of offspring mice, and effects in ME were more serious than FE. Notably, GATA4 protein levels in hearts in ME were significantly lower than that of MC, accompanied by down-regulation of histone acetyltransferase (HAT)-p300 and up-regulation of histone deacetylase-SIRT3. As GATA4 downstream genes, ratios of β-MHC gene expression to α-MHC significantly raised in ME relative to the MC. Results of chromatin immunoprecipitation (ChIP)-qPCR assay found that binding levels of acetylated histone 3 lysine 9 (H3K9ac) in GATA4 promoter region in the hearts of ME or FE were markedly decreased compared with their corresponding control groups. It suggested that maternal exposure to PM2.5 may cause cardiac injury in the offspring, heart damage of male mice was worse than female mice, in which process HAT-p300, H3K9ac, transcription factor GATA4 may play an important regulation role.

Exploration of the Molecular Mechanism for Lipoprotein Lipase Expression Variations in SH-SY5Y Cells Exposed to Different Doses of Amyloid-Beta Protein.

Progressive accumulation of amyloid-β (Aβ) plaques in the brain is a characteristic pathological change in Alzheimer’s disease (AD). We previously found the expression of lipoprotein lipase (LPL) was increased in SH-SY5Y cells exposed to low-dose Aβ and decreased in cells with high-dose Aβ exposure, but the molecular mechanism is still unclear. Based on previous studies, the opposite regulation of histone deacetylase2 (HDAC2) and HDAC3 on LPL expression probably explain the above molecular mechanism, in which microRNA-29a and peroxisome proliferator-activated receptor γ (PPARγ) may be involved. This study further revealed the mechanism of HDAC2 and HDAC3 on conversely regulating LPL expression. The results showed that HDAC2 down-regulated microRNA-29a by decreasing histone acetylation (Ace-H3K9) level in its promoter region, subsequently increasing LPL expression directly or through PPARγ/LPL pathway; HDAC3 decreased LPL expression through inhibiting Ace-H3K9 levels in LPL and PPARγ promoter regions and up-regulating microRNA-29a. This study also found that with increasing concentrations of Aβ in cells, HDAC2 and HDAC3 expression were gradually increased, and Ace-H3K9 levels in LPL and PPARγ promoter region regulated by HDAC3 were decreased correspondingly, while Ace-H3K9 levels in microRNA-29a promoter region modulated by HDAC2 were not decreased gradually but presented a U-shaped trend. These may lead to the results that a U-shaped alteration in microRNA-29a expression, subsequently leading to an inverse U-shaped alteration in PPARγ or LPL expression. In conclusion, HDAC2 and HDAC3 at least partly mediate LPL expression variations in different concentrations of Aβ exposed SH-SY5Y cells, in which microRNA-29a and PPARγ are involved, and the histone acetylation level in microRNA-29a promoter region plays a key role.

Nuclear-Translocation of ACLY Induced by Obesity Related Factors Enhances Pyrimidine Metabolism Through Regulating Histone Acetylation in Endometrial Cancer

Background: Endometrial cancer (EC) is a common female reproductive system cancer, and obesity is a major risk factor for the disease. ATP-citrate lyase (ACLY), a vital enzyme linking both glycolytic and lipid metabolism, plays important roles in cancer progression. However, there is little evidence of ACLY involvement in EC development. Methods: The ACLY expression in EC was evaluated by using TCGA and GEO databases and verified it using clinical samples by IHC and RT-PCR methods. The functions of ACLY was determined by both the vitro and vivo studies. Gene expression array, co-immunoprecipitation, TUNEL assay, EdU assay, chromatin immunoprecipitation and luciferase reporter assay were applied for mechanism dissection. Findings: ACLY was significantly upregulated in EC patients, particularly in the nucleus. Upregulated ACLY promoted EC cell proliferation and colony formation, and attenuated apoptosis. Mechanistically, cotreatment with obesity-related factors (estradiol, insulin and leptin) promoted nuclear translocation of ACLY through Akt-mediated phosphorylation of ACLY at Ser455 . Nuclear-localized ACLY increased histone acetylation levels, thus resulting in upregulation of pyrimidine metabolism genes, such as DHODH. Moreover, STAT3 altered the ACLY expression at the transcriptional level via directly binding to its promoter region. Interpretation: ACLY nuclear-translocation induced by obesity-related factors promotes EC progression by modulating histone acetylation levels, The ACLY axis could be served as potential therapeutic targets for the treatment of EC. Funding Statement: This research was supported by The National Natural Science Foundation of China (Grant number: 81974406) and The Sailing Program Foundation of Hunan Cancer Hospital. Declaration of Interests: The authors declare that they have no competing interests with the contents of this article. Ethics Approval Statement: The study was approved by the Research Ethics Committee of the Sixth People's Hospital, and informed consent was provided by all patients before this study.

Maternal Epigenetic Regulation Contributes to Prevention of Estrogen Receptor-negative Mammary Cancer with Broccoli Sprout Consumption.

Cruciferous vegetables have been of special interest due to the rich presence of bioactive compounds such as sulforaphane which show promising potential on cancer prevention and therapy as an epigenetic dietary strategy. Abnormal epigenetic alteration as one of the primary contributors to tumor development is closely related to breast cancer initiation and progression. In the present study, we investigated the effect of dietary broccoli sprouts (BSp), a common cruciferous vegetable, on prevention of estrogen receptor (ER)-negative mammary tumors at three different temporal exposure windows using a spontaneous breast cancer mouse model. Our findings indicate that maternal BSp treatment exhibited profound inhibitory and preventive effects on mammary cancer formation in the nontreated mouse offspring. The BSp diet administered to adult mice also showed suppressive effects on mammary cancer but was not as profound as the maternal BSp preventive effects. Moreover, such protective effects were linked with differentially expressed tumor- and epigenetic-related genes, as well as altered global histone acetylation, DNA methylation, and DNA hydroxymethylation levels. We also found that the expression changes of tumor-related genes were associated with the levels of histone methylation of H3K4 and H3K9 in the gene promoter regions. In addition, BSp-enriched sulforaphane was shown to increase protein expression of tumor suppressor genes such as p16 and p53 and inhibit the protein levels of Bmi1, DNA methyltransferases, and histone deacetylases in ERα-negative breast cancer cell lines. Collectively, these results suggest that maternal exposure to key phytochemicals may contribute to ER-negative mammary tumor prevention in their offspring through epigenetic regulations.

USP38 regulates the stemness and chemoresistance of human colorectal cancer via regulation of HDAC3

Histone modification represents a crucial level of gene expression regulation and is actively involved in the carcinogenesis of human colorectal cancer. Histone acetyltransferases and deacetylases modulate the landscape of histone acetylation, which controls key genes of colorectal cancer pathology. However, the fine tune of histone deacetylases, especially the modification of histone deacetylases that facilitate colorectal cancer, remains elusive. Here, we identified that an ubiquitin-specific protease (USP), USP38, was downregulated in clinical colorectal cancer samples and colorectal cancer cell lines. Importantly, our results showed that USP38 was a specific deubiquitinase of histone deacetylase 3 (HDAC3), which cleaved the lysine 63 ubiquitin chain. Ubiquitination of HDAC3 resulted in a decreased level of histone acetylation and finally led to upregulation of cancer stem cell-related genes. In addition, our results demonstrated a tumor suppressor role of USP38 in colorectal cancer via inhibiting cancer stem cell populations. Most importantly, the ubiquitination level of HDAC3 was responsible for USP38 mediated regulation of cancer stem cell-related transcripts. Our data provided functional insights of USP38 and HDAC3 in colorectal cancer and revealed novel mechanisms of ubiquitination mediated epigenetic regulation.

IgE Levels to Ascaris and House Dust Mite Allergens Are Associated With Increased Histone Acetylation at Key Type-2 Immune Genes.

BackgroundEpigenetic changes in response to allergen exposure are still not well understood. The aim of this study was to evaluate histone acetylation levels in peripheral blood leukocytes from humans naturally infected by intestinal parasites and perennially exposed to house dust mites (HDM).MethodsPeripheral blood mononuclear cells (PBMCs) were isolated by gradient centrifugation from 20 infected and 21 non-infected individuals living in a rural/village in Colombia. Histone 3 acetylation (H3Ac) and histone 4 acetylation (H4Ac) levels were measured in six immune genes previously associated with helminth immunity by chromatin immunoprecipitation (ChIP)-quantitative PCR. Then we analyzed the association between histone acetylation levels with total parasite egg burden and IgE levels.ResultsWe found an inverse correlation between H4Ac levels in the IL13 gene and egg worm burden that remained significant after adjustment by age [−0.20 (−0.32 to −0.09), p < 0.0001]. Moreover, we found significant associations between H4Ac levels in IL4 [0.32 (0.05–0.60), p = 0.02] and CHI3L1 [0.29 (0.08–0.51), p = 0.008] with the IgE levels to Ascaris lumbricoides. In addition, the levels of specific IgE antibodies to HDM were associated with H4Ac levels in the gene TNFSF13B encoding the B cell activating factor (BAFF) [0.51 (0.26–0.76), p < 0.001]. All values are presented as beta (95% CI).ConclusionHistone acetylation levels at key type-2 immune genes in humans were modified by nematode infection and HDM allergens and are associated with the intensity of the IgE response.

Loss of RBBP4 results in defective inner cell mass, severe apoptosis, hyperacetylated histones and preimplantation lethality in mice†.

Retinoblastoma-binding protein 4 (RBBP4) (also known as chromatin-remodeling factor RBAP48) is an evolutionarily conserved protein that has been involved in various biological processes. Although a variety of functions have been attributed to RBBP4 in vitro, mammalian RBBP4 has not been studied in vivo. Here we report that RBBP4 is essential during early mouse embryo development. Although Rbbp4 mutant embryos exhibit normal morphology at E3.5 blastocyst stage, they cannot be recovered at E7.5 early post-gastrulation stage, suggesting an implantation failure. Outgrowth (OG) assays reveal that mutant blastocysts cannot hatch from the zona or can hatch but then arrest without further development. We find that while there is no change in proliferation or levels of reactive oxygen species, both apoptosis and histone acetylation are significantly increased in mutant blastocysts. Analysis of lineage specification reveals that while the trophoblast is properly specified, both epiblast and primitive endoderm lineages are compromised with severe reductions in cell number and/or specification. In summary, these findings demonstrate the essential role of RBBP4 during early mammalian embryogenesis.

Histone hyperacetylation mediates enhanced IL-1β production in LPS/IFN-γ-stimulated macrophages.

SummaryUnder the condition of lipopolysaccharide (LPS)/interferon (IFN)‐γ activation, macrophage metabolism is converted from oxidative phosphorylation to glycolysis. In the present work, we analysed whether glycolysis could affect interleukin (IL)‐1β expression through altering histone acetylation levels in mouse bone marrow‐derived macrophages. Immunocytochemistry and Western blot analysis are used to characterize histone acetylation in macrophages stimulated by LPS/IFN‐γ. Real‐time polymerase chain reaction and enzyme‐linked immunosorbent assay were used to determine IL‐1β production. The metabolism of macrophages was monitored in real‐time by the Seahorse test. Our results showed that glycolytic metabolism could enhance histone acetylation and promote IL‐1β production in LPS/IFN‐γ‐activated macrophages. Moreover, increased production of IL‐1β by glycolysis was mediated through enhanced H3K9 acetylation. Importantly, it was found that a high dose of histone deacetylase inhibitor could also significantly increase the expression of IL‐1β in the absence of glycolytic metabolism. In conclusion, this study demonstrates that glycolytic metabolism could regulate IL‐1β expression by increasing histone acetylation levels in LPS/IFN‐γ‐stimulated macrophages.

Mocetinostat suppresses epidural fibrosis following laminectomy by inhibiting myofibroblast activation and increasing apoptosis.

To investigate the effect and mechanism of mocetinostat on diminishing epidural fibrosis. Dysregulated wound repair usually occurs after injury or surgery and is featured by excessive scar tissue contributed by fibrosis. Increasing researches demonstrated that histone acetylation, an epigenetic alteration, plays a crucial role in fibrosis. However, the mechanism of the complicated process remains unclear. In the current study, the effect of histone deacetylase (HDAC) inhibitor mocetinostat in a rat model of epidural fibrosis was detected, and it was discovered that mocetinostat suppressed myofibroblast activation and increased apoptosis by reducing Akt/GSK3b signaling. First, the levels of histone acetylation in the patients' epidural fibroblasts were analyzed. Then, mRNAs and proteins obtained from human fibroblasts following TGF-β activation and mocetinostat treatment in vitro were used to examine the influence of mocetinostat on the activation and survival of fibroblasts, so as to explore the related mechanism of mocetinostat. The laminectomy model was established in rats to observe the therapeutic effect of mocetinostat on epidural scar tissues. In this research, it was found that the increase of HDAC1 in human dura scar was accompanied by the aggravation of fibrosis. In addition, cell assay demonstrated that mocetinostat inhibited fibroblast activation and accelerated apoptosis by inhibiting Akt/GSK3b pathway. In the rat model, mocetinostat weakened scar hyperplasia and collagen deposition and effectively inhibited the process of epidural fibrosis. The above results indicate that mocetinostat inhibits HDAC1 expression and decreases the conduction of the AKT/GSK3b pathway in fibroblasts, leading to myofibroblast activation and apoptosis elevation. Hence, mocetinostat ameliorates epidural fibrosis.

Distinct roles for H4 and H2A.Z acetylation in RNA transcription in African trypanosomes

Despite histone H2A variants and acetylation of histones occurring in almost every eukaryotic organism, it has been difficult to establish direct functional links between canonical histones or H2A variant acetylation, deposition of H2A variants and transcription. To disentangle these complex interdependent processes, we devised a highly sensitive strategy for quantifying histone acetylation levels at specific genomic loci. Taking advantage of the unusual genome organization in Trypanosoma brucei, we identified 58 histone modifications enriched at transcription start sites (TSSs). Furthermore, we found TSS-associated H4 and H2A.Z acetylation to be mediated by two different histone acetyltransferases, HAT2 and HAT1, respectively. Whereas depletion of HAT2 decreases H2A.Z deposition and shifts the site of transcription initiation, depletion of HAT1 does not affect H2A.Z deposition but reduces total mRNA levels by 50%. Thus, specifically reducing H4 or H2A.Z acetylation levels enabled us to reveal distinct roles for these modifications in H2A.Z deposition and RNA transcription.

ATP depletion induced cochlear hair cells death through histone deacetylation in vitro

Previous studies have shown histone modifications being present in cochlear hair cells in animal models of hearing loss. Our past studies have shown that ATP depletion, histone deacetylase (HDAC) upregulation, and histone deacetylation occur in cochlea after noise exposure, and these are linked to hair cell death. Whether ATP depletion correlates with the expression level of HDACs and acetylation of histones is still unknown. In this study, we investigated the changes in the expression of HDACs and the level of histone acetylation in cochlear hair cells using an ATP-depleted explant culture of mouse organ of Corti. We found that the expression of HDAC3 and HDAC6 increased and hair cells were lost after oligomycin A (OA) treatment. Meanwhile, the acetylation level of histone H2B reduced. However, when oligomycin was combined with an HDAC inhibitor, trichostatin A (TSA), the acetylation level of histone H3 was restored. Moreover, combined treatment of oligomycin and TSA or sodium butyrate (NaB) attenuated oligomycin-induced cochlear hair cell loss. In conclusion, our results indicated that ATP depletion led to histone deacetylation and eventually resulted in hair cell death.

Wnt-3a Induces Epigenetic Remodeling in Human Dental Pulp Stem Cells.

Dental pulp stem cells (DPSCs) from adult teeth show the expression of a very complete repertoire of stem pluripotency core factors and a high plasticity for cell reprogramming. Canonical Wnt and Notch signaling pathways regulate stemness and the expression of pluripotency core factors in DPSCs, and even very short-term (48 h) activations of the Wnt pathway induce a profound remodeling of DPSCs at the physiologic and metabolic levels. In this work, DPSC cultures were exposed to treatments modulating Notch and Wnt signaling, and also induced to differentiate to osteo/adipocytes. DNA methylation, histone acetylation, histone methylation, and core factor expression levels where assessed by mass spectroscopy, Western blot, and qPCR. A short-term activation of Wnt signaling by WNT-3A induced a genomic DNA demethylation, and increased histone acetylation and histone methylation in DPSCs. The efficiency of cell reprogramming methods relies on the ability to surpass the epigenetic barrier, which determines cell lineage specificity. This study brings important information about the regulation of the epigenetic barrier by Wnt signaling in DPSCs, which could contribute to the development of safer and less aggressive reprogramming methodologies with a view to cell therapy.

Transcriptional and epigenetic regulation of ncx1 and ncx3 in the brain

Sodium-calcium exchanger (NCX) 1 and 3, have been demonstrated to play a relevant role in controlling the intracellular homeostasis of sodium and calcium ions in physiological and patho-physiological conditions. While NCX1 and NCX3 knocking-down have been both implicated in brain ischemia, several aspects of the epigenetic regulation of these two antiporters transcription were not yet well characterized. In response to stroke, NCX1 and NCX3 transcriptional regulation occurs from specific promoter sequences. Several evidences have shown that the expression of NCX1 and NCX3 can be determined by epigenetic modifications, consisting in changes of the histone acetylation levels on their promoter sequences. An interesting issue is that histone modifications at the NCX1 and NCX3 promoters could be linked to neurodegeneration occurring after stroke. Therefore, identifying the epigenetic regulation at the NCX1 and NCX3 promoters could permit to identify new molecular targets that can open new strategies for stroke treatment. The current review reassumes the recent knowledge of histone modifications of NCX1 and NCX3 genes in brain in physiological and patho-physiological conditions.

Insights Into the Function of the NuA4 Complex in Plants.

Chromatin remodeling plays a key role in the establishment and maintenance of gene expression patterns essential for plant development and responses to environmental factors. Post-translational modification of histones, including acetylation, is one of the most relevant chromatin remodeling mechanisms that operate in eukaryotic cells. Histone acetylation is an evolutionarily conserved chromatin signature commonly associated with transcriptional activation. Histone acetylation levels are tightly regulated through the antagonistic activity of histone acetyltransferases (HATs) and histone deacetylases (HDACs). In plants, different families of HATs are present, including the MYST family, which comprises homologs of the catalytic subunit of the Nucleosome Acetyltransferase of H4 (NuA4) complex in yeast. This complex mediates acetylation of histones H4, H2A, and H2A.Z, and is involved in transcriptional regulation, heterochromatin silencing, cell cycle progression, and DNA repair in yeast. In Arabidopsis and, other plant species, homologs for most of the yeast NuA4 subunits are present and although the existence of this complex has not been demonstrated yet, compelling evidence supports the notion that this type of HAT complex functions from mosses to angiosperms. Recent proteomic studies show that several Arabidopsis homologs of NuA4 components, including the assembly platform proteins and the catalytic subunit, are associated in vivo with additional members of this complex suggesting that a NuA4-like HAT complex is present in plants. Furthermore, the functional characterization of some Arabidopsis NuA4 subunits has uncovered the involvement of these proteins in the regulation of different plant biological processes. Interestingly, for most of the mutant plants deficient in subunits of this complex characterized so far, conspicuous defects in flowering time are observed, suggesting a role for NuA4 in the control of this plant developmental program. Moreover, the participation of Arabidopsis NuA4 homologs in other developmental processes, such as gametophyte development, as well as in cell proliferation and stress and hormone responses, has also been reported. In this review, we summarize the current state of knowledge on plant putative NuA4 subunits and discuss the latest progress concerning the function of this chromatin modifying complex.

Valproic acid enhances in vitro developmental competence of porcine handmade cloned embryos

Histone deacetylase inhibitors (HDACi) can change the histone acetylation and significantly enhance the developmental competence of the pre-implantation SCNT embryo. To find a suitable histone deacetylase inhibitor to improve the success rate and potentially developmental ability of handmade cloning (HMC) embryos of porcine, we preferred the histone deacetylase inhibitors VPA to study the effect on HMC embryo development, their histone acetylation level and the expression level of relevant genes. The blastocyst rate and a number of blastocyst cells of HMC embryos treated with VPA (HMC-V) were significantly higher than that of control (HMC-C). In addition, the acetylation level (acH3K14) of HMC-V embryos at 2-cell and blastocyst stage was significantly higher that of PA HMC-C embryos. However, the acetylation H3K14 of embryos at 1-cell, 2-cell and blastocyst stage had no significant difference between PA and HMC-C embryos. The expression level of Hat1, Oct4 and Nanog were higher in HMC-V blastocysts, compared to PA and HMC-C blastocysts. In contrast, the Hdac2 expression level was lower in HMC-V blastocysts compared to those of the PA and HMC-C blastocysts. Our results demonstrated that HMC embryos treated with VPA that could promote the pre-implantation development and increase the levels of histone H3K14 acetylation and expression of the OCT4 gene, while reduced the Hdac2 gene expression with a comparable level of PA and HMC-C embryos. Our results pointed out that VPA could effectively correct the abnormal histone acetylation during the HMC embryo development and subsequently improve the full-term developmental potential of the HMC embryos after embryo transplantation.

Histone Acetylation at the Promoter for the Transcription Factor PuWRKY31 Affects Sucrose Accumulation in Pear Fruit.

Sugar content is an important trait of fleshy fruit, and elevating Suc levels is a major goal in horticultural crop breeding. Here, we examined the sugar content in two varieties of the Ussurian pear (Pyrus ussuriensis), 'Nanguo' (NG) and its bud sport (BNG), and we found that Suc content was higher in BNG fruit than in NG fruit. We compared the transcriptomes of the two varieties using RNA sequencing and identified a SWEET (Sugars Will Eventually be Exported Transporter) gene, PuSWEET15, expressed at higher levels in BNG fruit. Heterologous expression of PuSWEET15 in a SUSY7/ura yeast (Saccharomyces cerevisiae) strain showed that PuSWEET15 is an active Suc transporter. Overexpression of PuSWEET15 in NG pear fruit increased Suc content, while silencing of PuSWEET15 in BNG fruit decreased Suc content. The WRKY transcription factor PuWRKY31 was also expressed more highly in BNG fruit than in NG fruit, and we found that PuWRKY31 bound to the PuSWEET15 promoter and induced its transcription. The histone acetylation level of the PuWRKY31 promoter was higher in BNG fruit, suggesting a mechanism by which Suc levels can be elevated.

Wheat Elongator subunit 4 is required for epigenetic regulation of host immune response to Rhizoctonia cerealis

Wheat (Triticum aestivum) is necessary for global food security. The necrotrophic fungus Rhizoctonia cerealis is the causal agent of sharp eyespot, a devastating disease of wheat. Although the Elongator complex, composed of six subunits, has been implicated in growth, development, and innate immunity in Arabidopsis, little is known about its functions in wheat or the involvement of Elongator subunit 4 in histone acetylation. In this study, we identified the Elongator subunit 4-encoding gene TaELP4 in wheat resistance response to R. cerealis, and verified that TaELP4 increased histone acetylation in regions of defense-associated genes and regulated immune response to R. cerealis. TaELP4 was more highly expressed in resistant than in susceptible wheat cultivars and was induced in resistant wheat after infection by R. cerealis. Silencing of TaELP4 in wheat not only impaired resistance to R. cerealis, but also repressed both histone acetylation levels and the expression of a subset of defense-associated genes, including TaAGC1, TaCPK7-D, TaPAL5, Defensin, and Chitinase2. Ectopic expression of TaELP4 in Arabidopsis increased histone acetylation levels in coding and promoter regions of defense genes and increased their transcription, leading to increased resistance to infection by the pathogen Botrytis cinerea. These results suggest that TaELP4 positively regulates innate immune responses of wheat and Arabidopsis to R. cerealis and B. cinerea by increasing histone acetylation levels of defense-associated genes and increasing their transcription. This study has shed light on the involvement of TaELP4 in histone acetylation and resistance response against R. cerealis. TaELP4 may potentially be used to improve wheat resistance against sharp eyespot.

Maternal obesogenic diet combined with postnatal exposure to high-fat diet induces metabolic alterations in offspring.

Maternal obesity has been shown to impact the offspring health during childhood and adult life. This study aimed to evaluate whether maternal obesity combined with postnatal exposure to an obesogenic diet could induce metabolic alterations in offspring. Female CD1 mice were fed a control diet (CD, 11.1% of energy from fat) or with a high-fat diet (HFD, 44.3% of energy from fat) for 3 months. After weaning, pups born from control and obese mothers were fed with CD or HFD for 3 months. Both mothers and offspring were weighted weekly and several blood metabolic parameters levels were evaluated. Here, we present evidence that the offspring from mothers exposed to a HFD showed increased acetylation levels of histone 3 on lysine 9 (H3K9) in the liver at postnatal Day 1, whereas the levels of acetylation of H4K16, dimethylation of H3K27, and trimethylation of H3K9 showed no change. We also observed a higher perinatal weight and increased blood cholesterol levels when compared to the offspring on postnatal Day 1 born from CD-fed mothers. When mice born from obese mothers were fed with HFD, we observed that they gained more weight, presented higher blood cholesterol levels, and abdominal adipose tissue than mice born to the same mothers but fed with CD. Collectively, our results point toward maternal obesity and HFD consumption as a risk factor for epigenetic changes in the liver of the offspring, higher perinatal weight, increased weight gain, and altered blood cholesterol levels.