Unraveling the Role of JMJD1B in Genome Stability and the Malignancy of Melanomas.

Genome instability relies on preserving the chromatin structure, with any histone imbalances threating DNA integrity. Histone synthesis occurs in the cytoplasm, followed by a maturation process before their nuclear translocation. This maturation involves protein folding and the establishment of post-translational modifications. Disruptions in this pathway hinder chromatin assembly and contribute to genome instability. JMJD1B, a histone demethylase, not only regulates gene expression but also ensures a proper supply of histones H3 and H4 for the chromatin assembly. Reduced JMJD1B levels lead to the cytoplasmic accumulation of histones, causing defects in the chromatin assembly and resulting in DNA damage. To investigate the role of JMJD1B in regulating genome stability and the malignancy of melanoma tumors, we used a JMJD1B/KDM3B knockout in B16F10 mouse melanoma cells to perform tumorigenic and genome instability assays. Additionally, we analyzed the transcriptomic data of human cutaneous melanoma tumors. Our results show the enhanced tumorigenic properties of JMJD1B knockout melanoma cells both in vitro and in vivo. The γH2AX staining, Micrococcal Nuclease sensitivity, and comet assays demonstrated increased DNA damage and genome instability. The JMJD1B expression in human melanoma tumors correlates with a lower mutational burden and fewer oncogenic driver mutations. Our findings highlight JMJD1B's role in maintaining genome integrity by ensuring a proper histone supply to the nucleus, expanding its function beyond gene expression regulation. JMJD1B emerges as a crucial player in preserving genome stability and the development of melanoma, with a potential role as a safeguard against oncogenic mutations.

Unraveling the role of sperm retained histones in bull fertility and daughter fertility.

During spermatogenesis, a substantial proportion of histones are substituted by protamine to condense the genome within the sperm head. Studies indicate that a minority of histones, typically ranging from 1 to 15 %, persist in mammalian sperm post-substitution. The persistence of histones in the zygote facilitates chromatin accessibility to transcription factors in regions crucial for early embryonic development. Nevertheless, the potential causal relationship between retained histones and fertility phenotypes remains uncertain. This study seeks to investigate this relationship. The results indicate that in mature bovine sperm, regions of DNA associated with fertility that bind to histones are primarily concentrated in promoters and transcription start sites, potentially impacting bull fertility and offspring fertility through the regulation of relevant genes. Furthermore, microRNAs and estradiol/ESR are suggested to be the main regulators of the canonical pathways identified, highlighting the need for additional research to investigate their potential utility as biomarkers.

Chronic ethanol exposure decreases H3K27me3 in the Il6 promoter region of macrophages and generates persistent dysfunction on neutrophils during fungal infection.

OBJECTIVE AND DESIGN: The aim of this study was to investigate the effects of ethanol exposure on epigenetic markers in bone marrow (BM) and their impact on inflammatory response during Aspergillus fumigatus infection. RESULTS: Chronic ethanol exposure decreased H3K27me3 enrichment in the Il6 promoter region while increased H3K4me3 enrichment in Tnf. Chimeric mice were generated by transplanting BM from mice exposed to ethanol or water. Infection of ethanol-chimeric mice culminated in higher clinical scores, although there was no effect on mortality. However, previous chronic exposure to ethanol affects persistently the inflammatory response in lung tissue, demonstrated by increased lung damage, neutrophil accumulation and IL-6, TNF and CXCL2 production in ethanol-chimeric mice, resulting in a decreased neutrophil infiltration into the alveolar space. Neutrophil killing and phagocytosis were also significantly lower. Moreover, BM derived macrophages (BMDM) from ethanol-chimeric mice stimulated with A. fumigatus conidia exhibited higher levels of TNF, CXCL2 and IL-6 release and a higher killing activity. The Il6 promoter of BMDM from ethanol-chimeric mice exhibited a reduction in H3K27me3 enrichment, a finding also observed in BM donors exposed to ethanol. CONCLUSIONS: These evidences demonstrate that prior chronic alcohol exposure of bone-marrow modify immune effector cells functions impairing the inflammatory response during A. fumigatus infection. These findings highlight the persistent impact of chronic ethanol exposure on infectious disease outcomes.

A novel role of AIM2 inflammasome-mediated pyroptosis in radiofrequency ablation of hepatocellular carcinoma.

INTRODUCTION AND OBJECTIVES: The absence of melanoma 2 (AIM2) protein triggers the activation of the inflammasome cascade. It is unclear whether AIM2 plays a role in hepatocellular carcinoma (HCC) and radiofrequency ablation (RFA), which uses radiofrequency waves to treat tumors. In this study, we investigated if RFA could induce pyroptosis, also called cell inflammatory necrosis, in HCC through AIM2-inflammasome signaling in vivo and in vitro. MATERIALS AND METHODS: BALB/c nude mice were used to generate HepG2 or SMMC-7721 cell-derived tumor xenografts. HCC cells with knockdown or overexpression of AIM2 were created using short hairpin RNA (shRNA) and expression vector transfection, respectively, for functional and mechanistic studies. Downstream effects were examined using flow cytometry, qRT-PCR, ELISAs, and other molecular assays. RESULTS: RFA significantly suppressed tumor growth in HCC cell xenografts. Flow cytometry analysis revealed that RFA could induce pyroptosis. Furthermore, AIM2, NLRP3, caspase-1, γ-H2AX, and DNA-PKc had significantly greater expression levels in liver tissues from mice treated with RFA compared with those of the controls. Additionally, interleukin (IL)-1ß and IL-18 expression levels were significantly higher in the HCC cell-derived xenograft mice treated with RFA compared with those without RFA. Notably, a significantly greater effect was achieved in the RFA complete ablation group versus the partial ablation group. Knockdown or overexpression of AIM2 in HCC cells demonstrated that AIM2 exerted a role in RFA-induced pyroptosis. CONCLUSIONS: RFA can suppress HCC tumor growth by inducing pyroptosis via AIM2. Therefore, therapeutically intervening with AIM2-mediated inflammasome signaling may help improve RFA treatment outcomes for HCC patients.

From inside to outside: exploring extracellular antimicrobial histone-derived peptides as multi-talented molecules.

The emergence of bacterial resistance to antibiotics poses a global health threat, necessitating innovative solutions. The contemporary challenge lies in bacterial resistance, impacting morbidity, mortality, and global economies. Antimicrobial peptides (AMPs) offer a promising avenue for addressing antibiotic resistance. The Antimicrobial Peptide Database catalogs 3569 peptides from various organisms, representing a rich resource for drug development. Histones, traditionally recognized for their role in nucleosome structures, have gained attention for their extracellular functions, including antimicrobial and immunomodulatory properties. This review aims to thoroughly investigate antimicrobial peptides derived from histones in various organisms, elucidating their mechanisms. In addition, it gives us clues about how extracellular histones might be used in drug delivery systems to fight bacterial infections. This comprehensive analysis emphasizes the importance of histone-derived peptides in developing innovative therapeutic strategies for evolving bacterial challenges.

Stem cell-conditioned medium improves methylation patterns and quality of caprine preantral follicles.

In brief: Conditioned medium from Wharton's jelly mesenchymal stem cells improved tissue and preantral follicle outcomes, preventing adverse effects of oxidative stress, apoptosis, and epigenetic changes. Abstract: This study investigated the methylation patterns of H3K4me3 and H3K9me3, as well as the mRNA expression of genes encoding the epigenetic regulators KDM1AX1, KDM1AX2, and KDM3A in goat preantral follicles developed in vivo (Uncultured control) or after in vitro culture for 7 days in either the absence (α-MEM+) or presence of conditioned medium (α-MEM+ + CM) from Wharton's jelly mesenchymal stem cells (WJ-MSCs). In the invivo setting, all follicular categories exhibited similar H3K4me3 and H3K9me3 patterns, and transcripts of KDM1AX1, KDM1AX2, and KDM3A were detected in all samples. During in vitro culture, α-MEM+ + CM enhanced several important aspects. It increased the percentage of normal growing follicles, oocyte diameters across all categories, stromal cell density, and the H3K4me3 methylation pattern in preantral follicles. Simultaneously, it decreased the levels of reduced thiols and reactive oxygen species in the spent media, diminished the presence of lipofuscin aggresomes, lowered granulosa cell apoptotic rates, and reduced the H3K9me3 methylation pattern in preantral follicles. In conclusion, the findings from this study provide compelling evidence that supplementing the in vitro culture medium (α-MEM+) with CM from WJ-MSCs has a protective effect on goat preantral follicles. Notably, CM supplementation preserved follicular survival, as evidenced by enhanced follicular and oocyte growth and increased stromal cell density when compared to the standard culture conditions in the α-MEM+ medium. Furthermore, CM reduced oxidative stress and apoptosis and promoted alterations in H3K4me3 and H3K9me3 patterns.

Regulation of seed dormancy by histone post-translational modifications in the model plant Arabidopsis thaliana.

Plants synchronize their growth and development with environmental changes, which is critical for their survival. Among their life cycle transitions, seed germination is key for ensuring the survival and optimal growth of the next generation. However, even under favorable conditions, often germination can be blocked by seed dormancy, a regulatory multilayered checkpoint integrating internal and external signals. Intricate genetic and epigenetic mechanisms underlie seed dormancy establishment, maintenance, and release. In this review, we focus on recent advances that shed light on the complex mechanisms associated with physiological dormancy, prevalent in seed plants, with Arabidopsis thaliana serving as a model. Here, we summarize the role of multiple epigenetic regulators, but with a focus on histone modifications such as acetylation and methylation, that finely tune dormancy responses and influence dormancy-associated gene expression. Understanding these mechanisms can lead to a better understanding of seed biology in general, as well as resulting in the identification of possible targets for breeding climate-resilient plants.

General regulatory factors exert differential effects on nucleosome sliding activity of the ISW1a complex.

BACKGROUND: Chromatin dynamics is deeply involved in processes that require access to DNA, such as transcriptional regulation. Among the factors involved in chromatin dynamics at gene regulatory regions are general regulatory factors (GRFs). These factors contribute to establishment and maintenance of nucleosome-depleted regions (NDRs). These regions are populated by nucleosomes through histone deposition and nucleosome sliding, the latter catalyzed by a number of ATP-dependent chromatin remodeling complexes, including ISW1a. It has been observed that GRFs can act as barriers against nucleosome sliding towards NDRs. However, the relative ability of the different GRFs to hinder sliding activity is currently unknown. RESULTS: Considering this, we performed a comparative analysis for the main GRFs, with focus in their ability to modulate nucleosome sliding mediated by ISW1a. Among the GRFs tested in nucleosome remodeling assays, Rap1 was the only factor displaying the ability to hinder the activity of ISW1a. This effect requires location of the Rap1 cognate sequence on linker that becomes entry DNA in the nucleosome remodeling process. In addition, Rap1 was able to hinder nucleosome assembly in octamer transfer assays. Concurrently, Rap1 displayed the highest affinity for and longest dwell time from its target sequence, compared to the other GRFs tested. Consistently, through bioinformatics analyses of publicly available genome-wide data, we found that nucleosome occupancy and histone deposition in vivo are inversely correlated with the affinity of Rap1 for its target sequences in the genome. CONCLUSIONS: Our findings point to DNA binding affinity, residence time and location at particular translational positions relative to the nucleosome core as the key features of GRFs underlying their roles played in nucleosome sliding and assembly.

Epigenetic reprogramming of H3K4me3 in adipose-derived stem cells by HFS diet consumption leads to a disturbed transcriptomic profile in adipocytes.

Adipose tissue metabolism is actively involved in the regulation of energy balance. Adipose-derived stem cells (ASCs) play a critical role in maintaining adipose tissue function through their differentiation into mature adipocytes (Ad). This study aimed to investigate the impact of an obesogenic environment on the epigenetic landscape of ASCs and its impact on adipocyte differentiation and its metabolic consequences. Our results showed that ASCs from rats on a high-fat sucrose (HFS) diet displayed reduced adipogenic capacity, increased fat accumulation, and formed larger adipocytes than the control (C) group. Mitochondrial analysis revealed heightened activity in undifferentiated ASC-HFS but decreased respiratory and glycolytic capacity in mature adipocytes. The HFS diet significantly altered the H3K4me3 profile in ASCs on genes related to adipogenesis, mitochondrial function, inflammation, and immunomodulation. After differentiation, adipocytes retained H3K4me3 alterations, confirming the upregulation of genes associated with inflammatory and immunomodulatory pathways. RNA-seq confirmed the upregulation of genes associated with inflammatory and immunomodulatory pathways in adipocytes. Overall, the HFS diet induced significant epigenetic and transcriptomic changes in ASCs, impairing differentiation and causing dysfunctional adipocyte formation.NEW & NOTEWORTHY Obesity is associated with the development of chronic diseases like metabolic syndrome and type 2 diabetes, and adipose tissue plays a crucial role. In a rat model, our study reveals how an obesogenic environment primes adipocyte precursor cells, leading to epigenetic changes that affect inflammation, adipogenesis, and mitochondrial activity after differentiation. We highlight the importance of histone modifications, especially the trimethylation of histone H3 to lysine 4 (H3K4me3), showing its influence on adipocyte expression profiles.

Inhibition of histone deacetylases class I improves adipogenic differentiation of human periodontal ligament cells.

Periodontal ligament stem cells (PDLSCs) show plasticity towards the adipogenic lineage; however, little has been done on the participation of epigenetic mechanisms. Histone acetylation is a dynamic process, though balanced by histone acetyltransferases (HATs) and histone deacetylases (HDACs) activities. This process can be halted by HDACs inhibitors, such as trichostatin A (TSA) and valproic acid (VPA). This study aimed to determine the role of HDACs class I in adipogenic differentiation of PDL cells. PDLSCs were treated with TSA at concentrations of 100, 200, and 250 nM, or VPA at 1, 4 and 8 mM. Cell viability was assessed using MTT assays. Gene expression of pluripotency markers (NANOG, OCT4, SOX2), HAT genes (p300, GCN5), and HDACs genes (HDAC1-3) was analyzed by RT-qPCR. Adipogenic differentiation was evaluated via oil red O staining, and acetylation of histone H3 lysine 9 (H3K9ac) was examined by Western blot. VPA treatment resulted in a 60% reduction in cell proliferation, compared to a 50% when using TSA. Cell viability was not affected by either inhibitor. Furthermore, both TSA and VPA induced adipogenic differentiation, through an increase in the deposition of lipid droplets and in GCN5 and p300 expression were observed. Western blot analysis showed that TSA increased H3K9ac levels on adipogenic differentiation of PDLSCs. These findings highlight the potential of HDAC inhibitors as a tool for modulating H3K9 acetylation status and thus influencing adipogenic differentiation of PDLCs.

Deciphering epigenetic regulations in the inflammatory pathways of atopic dermatitis.

Atopic dermatitis, commonly referred to as atopic eczema, is a persistent inflammatory skin disorder that predominantly manifests in children but may endure into adulthood. Its clinical management poses challenges due to the absence of a definitive cure, and its prevalence varies across ethnicities, genders, and geographic locations. The epigenetic landscape of AD includes changes in DNA methylation, changes in histone acetylation and methylation, and regulation by non-coding RNAs. These changes affect inflammatory and immune mechanisms, and research has identified AD-specific variations in DNA methylation, particularly in the affected epidermis. Histone modifications, including acetylation, have been associated with the disruption of skin barrier function in AD, suggesting the potential therapeutic benefit of histone deacetylase inhibitors such as belinostat. Furthermore, non-coding RNAs, particularly microRNAs and long non-coding RNAs (lncRNAs), have been implicated in modulating various cellular processes central to AD pathogenesis. Therapeutic implications in AD include the potential use of DNA methylation inhibitors and histone deacetylase inhibitors to correct aberrant methylation patterns and modulate gene expression related to immune responses and skin barrier functions. Additionally, the emerging role of lncRNAs suggests the possibility of using small interfering RNAs or antisense oligonucleotides to inhibit lncRNAs and adjust their regulatory impact on gene expression. In conclusion, the importance of epigenetic elements in AD is becoming increasingly clear as studies highlight the contribution of DNA methylation, histone modifications and, control by non-coding RNAs to the onset and progression of the disease. Understanding these epigenetic changes provides valuable insights for developing targeted therapeutic strategies.

Reversion from basal histone H4 hypoacetylation at the replication fork increases DNA damage in FANCA deficient cells.

The FA/BRCA pathway safeguards DNA replication by repairing interstrand crosslinks (ICL) and maintaining replication fork stability. Chromatin structure, which is in part regulated by histones posttranslational modifications (PTMs), has a role in maintaining genomic integrity through stabilization of the DNA replication fork and promotion of DNA repair. An appropriate balance of PTMs, especially acetylation of histones H4 in nascent chromatin, is required to preserve a stable DNA replication fork. To evaluate the acetylation status of histone H4 at the replication fork of FANCA deficient cells, we compared histone acetylation status at the DNA replication fork of isogenic FANCA deficient and FANCA proficient cell lines by using accelerated native immunoprecipitation of nascent DNA (aniPOND) and in situ protein interactions in the replication fork (SIRF) assays. We found basal hypoacetylation of multiple residues of histone H4 in FA replication forks, together with increased levels of Histone Deacetylase 1 (HDAC1). Interestingly, high-dose short-term treatment with mitomycin C (MMC) had no effect over H4 acetylation abundance at the replication fork. However, chemical inhibition of histone deacetylases (HDAC) with Suberoylanilide hydroxamic acid (SAHA) induced acetylation of the FANCA deficient DNA replication forks to levels comparable to their isogenic control counterparts. This forced permanence of acetylation impacted FA cells homeostasis by inducing DNA damage and promoting G2 cell cycle arrest. Altogether, this caused reduced RAD51 foci formation and increased markers of replication stress, including phospho-RPA-S33. Hypoacetylation of the FANCA deficient replication fork, is part of the cellular phenotype, the perturbation of this feature by agents that prevent deacetylation, such as SAHA, have a deleterious effect over the delicate equilibrium they have reached to perdure despite a defective FA/BRCA pathway.

Targeting the reprogrammed metabolism in H3.3K27M pediatric high-grade gliomas.

Recent studies in Diffuse Midline Gliomas (DMG) demonstrated a strong connection between epigenome dysregulation and metabolic rewiring. Here, we evaluated the value of targeting a glycolytic protein named Phosphofructo-2-kinase/Fructose-2,6-bisphosphatase 3 (PFKFB3) in H3.3K27M DMG. We observed that the viability of H3.3K27M cells is dramatically reduced by PFK15, a potent inhibitor of PFKFB3. Furthermore, PFKFB3 inhibition induced apoptosis and G2/M arrest. Interestingly, CRISPR-Knockout of the K27M mutant allele has a synergistic effect on the observed phenotype. Altogether, we identified PFKFB3 as a new target for H3.3K27M DMG, making PFK15 a potential candidate for future animal studies and clinical trials.

Evidence of epigenetic landscape shifts in mucopolysaccharidosis IIIB and IVA.

Lysosomal storage diseases (LSDs) are a group of monogenic diseases characterized by mutations in genes coding for proteins associated with the lysosomal function. Despite the monogenic nature, LSDs patients exhibit variable and heterogeneous clinical manifestations, prompting investigations into epigenetic factors underlying this phenotypic diversity. In this study, we focused on the potential role of epigenetic mechanisms in the pathogenesis of mucopolysaccharidosis IIIB (MPS IIIB) and mucopolysaccharidosis IVA (MPS IVA). We analyzed DNA methylation (5mC) and histone modifications (H3K14 acetylation and H3K9 trimethylation) in MPS IIIB and MPS IVA patients' fibroblasts and healthy controls. The findings revealed that global DNA hypomethylation is present in cell lines for both diseases. At the same time, histone acetylation was increased in MPS IIIB and MPS IVA cells in a donor-dependent way, further indicating a shift towards relaxed open chromatin in these MPS. Finally, the constitutive heterochromatin marker, histone H3K9 trimethylation, only showed reduced clustering in MPS IIIB cells, suggesting limited alterations in heterochromatin organization. These findings collectively emphasize the significance of epigenetic mechanisms in modulating the phenotypic variations observed in LSDs. While global DNA hypomethylation could contribute to the MPS pathogenesis, the study also highlights individual-specific epigenetic responses that might contribute to phenotypic heterogeneity. Further research into the specific genes and pathways affected by these epigenetic changes could provide insights into potential therapeutic interventions for these MPS and other LSDs.

Neural tube defects and epigenetics: role of histone post-translational histone modifications.

Neural tube defects (NTDs) are the most common congenital anomalies of the CNS. It is widely appreciated that both genetic and environmental factors contribute to their etiology. The inability to ascribe clear genetic patterns of inheritance to various NTD phenotypes suggests it is possible that epigenetic mechanisms are involved in the etiology of NTDs. In this context, the contribution of DNA methylation as an underlying contributing factor to the etiology of NTDs has been extensively reviewed. Here, an updated accounting of the evidence linking post-translational histone modifications to these birth defects, relying heavily upon studies in humans, and the possible molecular implications inferred from reports based on cellular and animal models, are presented.

Epigenetic changes in shear-stressed endothelial cells.

Epigenetic changes, particularly histone compaction modifications, have emerged as critical regulators in the epigenetic pathway driving endothelial cell phenotype under constant exposure to laminar forces induced by blood flow. However, the underlying epigenetic mechanisms governing endothelial cell behavior in this context remain poorly understood. To address this knowledge gap, we conducted in vitro experiments using human umbilical vein endothelial cells subjected to various tensional forces simulating pathophysiological blood flow shear stress conditions, ranging from normotensive to hypertensive forces. Our study uncovers a noteworthy observation wherein endothelial cells exposed to high shear stress demonstrate a decrease in the epigenetic marks H3K4ac and H3K27ac, accompanied by significant alterations in the levels of HDAC (histone deacetylase) proteins. Moreover, we demonstrate a negative regulatory effect of increased shear stress on HOXA13 gene expression and a concomitant increase in the expression of the long noncoding RNA, HOTTIP, suggesting a direct association with the suppression of HOXA13. Collectively, these findings represent the first evidence of the role of histone-related epigenetic modifications in modulating chromatin compaction during mechanosignaling of endothelial cells in response to elevated shear stress forces. Additionally, our results highlight the importance of understanding the physiological role of HOXA13 in vascular biology and hypertensive patients, emphasizing the potential for developing small molecules to modulate its activity. These findings warrant further preclinical investigations and open new avenues for therapeutic interventions targeting epigenetic mechanisms in hypertensive conditions.

The central role of pyruvate metabolism on the epigenetic maturation and transcriptional profile of bovine oocytes.

In brief: Pyruvate metabolism is one of the main metabolic pathways during oocyte maturation. This study demonstrates that pyruvate metabolism also regulates the epigenetic and molecular maturation in bovine oocytes. Abstract: Pyruvate, the final product of glycolysis, undergoes conversion into acetyl-CoA within the mitochondria of oocytes, serving as a primary fuel source for the tricarboxylic acid (TCA) cycle. The citrate generated in the TCA cycle can be transported to the cytoplasm and converted back into acetyl-CoA. This acetyl-CoA can either fuel lipid synthesis or act as a substrate for histone acetylation. This study aimed to investigate how pyruvate metabolism influences lysine 9 histone 3 acetylation (H3K9ac) dynamics and RNA transcription in bovine oocytes during in vitro maturation (IVM). Bovine cumulus-oocyte complexes were cultured in vitro for 24 h, considering three experimental groups: Control (IVM medium only), DCA (IVM supplemented with sodium dichloroacetate, a stimulant of pyruvate oxidation into acetyl-CoA), or IA (IVM supplemented with sodium iodoacetate, a glycolysis inhibitor). The results revealed significant alterations in oocyte metabolism in both treatments, promoting the utilization of lipids as an energy source. These changes during IVM affected the dynamics of H3K9ac, subsequently influencing the oocyte's transcriptional activity. In the DCA and IA groups, a total of 148 and 356 differentially expressed genes were identified, respectively, compared to the control group. These findings suggest that modifications in pyruvate metabolism trigger the activation of metabolic pathways, particularly lipid metabolism, changing acetyl-CoA availability and H3K9ac levels, ultimately impacting the mRNA content of in vitro matured bovine oocytes.

A phased genome assembly of a Colombian Trypanosoma cruzi TcI strain and the evolution of gene families.

Chagas is an endemic disease in tropical regions of Latin America, caused by the parasite Trypanosoma cruzi. High intraspecies variability and genome complexity have been challenges to assemble high quality genomes needed for studies in evolution, population genomics, diagnosis and drug development. Here we present a chromosome-level phased assembly of a TcI T. cruzi strain (Dm25). While 29 chromosomes show a large collinearity with the assembly of the Brazil A4 strain, three chromosomes show both large heterozygosity and large divergence, compared to previous assemblies of TcI T. cruzi strains. Nucleotide and protein evolution statistics indicate that T. cruzi Marinkellei separated before the diversification of T. cruzi in the known DTUs. Interchromosomal paralogs of dispersed gene families and histones appeared before but at the same time have a more strict purifying selection, compared to other repeat families. Previously unreported large tandem arrays of protein kinases and histones were identified in this assembly. Over one million variants obtained from Illumina reads aligned to the primary assembly clearly separate the main DTUs. We expect that this new assembly will be a valuable resource for further studies on evolution and functional genomics of Trypanosomatids.

Histone Methyltransferase G9a Plays an Essential Role on Nicotine Preference in Zebrafish.

Psychostimulants regulate behavioral responses in zebrafish via epigenetic mechanisms. We have previously shown that DNA methylation and histone deacetylase (HDAC) inhibition abolish nicotine-induced conditioned place preference (CPP) but little is known about the role of histone methylation in addictive-like behaviors. To assess the influence of histone methylation on nicotine-CPP, zebrafish were treated with a histone (H3) lysine-9 (K9) dimethyltransferase G9a/GLP inhibitor, BIX-01294 (BIX), which was administered before conditioning sessions. We observed a dual effect of the inhibitor BIX: at high doses inhibited while at low doses potentiated nicotine reward. Transcriptional expression of α6 and α7 subunits of the nicotinic acetylcholine receptor and of G9a, DNA methyl transferase-3, and HDAC-1 was upregulated in zebrafish with positive scores for nicotine-CPP. Changes in relative levels of these mRNA molecules reflected the effects of BIX on nicotine reward. BIX treatment per sé did not affect transcriptional levels of epigenetic enzymes that regulate trimethylation or demethylation of H3. BIX reduced H3K9me2 protein levels in a dose-dependent manner in key structures of the reward pathway. Thus, our findings indicated that different doses of BIX differentially affect nicotine CPP via strong or weak inhibition of G9a/GLP activity. Additionally, we found that the lysine demethylase inhibitor daminozide abolished nicotine-CPP and drug seeking. Our data demonstrate that H3 methylation catalyzed by G9a/GLP is involved in nicotine-CPP induction. Dimethylation of K9 at H3 is an important epigenetic modification that should be considered as a potential therapeutic target to treat nicotine reward and perhaps other drug addictions.

Histone 3 Trimethylation Patterns are Associated with Resilience or Stress Susceptibility in a Rat Model of Major Depression Disorder.

Major Depressive Disorder (MDD) is a severe and multifactorial psychiatric condition. Evidence has shown that environmental factors, such as stress, significantly explain MDD pathophysiology. Studies have hypothesized that changes in histone methylation patterns are involved in impaired glutamatergic signaling. Based on this scenario, this study aims to investigate histone 3 involvement in depression susceptibility or resilience in MDD pathophysiology by investigating cellular and molecular parameters related to i) glutamatergic neurotransmission, ii) astrocytic functioning, and iii) neurogenesis. For this, we subjected male Wistar rats to the Chronic Unpredictable Mild Stress (CUMS) model of depression. We propose that by evaluating the sucrose consumption, open field, and object recognition test performance from animals submitted to CUMS, it is possible to predict with high specificity rats with susceptibility to depressive-like phenotype and resilient to the depressive-like phenotype. We also demonstrated, for the first time, that patterns of H3K4me3, H3K9me3, H3K27me3, and H3K36me3 trimethylation are strictly associated with the resilient or susceptible to depressive-like phenotype in a brain-region-specific manner. Additionally, susceptible animals have reduced DCx and GFAP and resilient animals present increase of AQP-4 immunoreactivity. Together, these results provide evidence that H3 trimethylations are related to the development of the resilient or susceptible to depressive-like phenotype, contributing to further advances in the pathophysiology of MDD and the discovery of mechanisms behind resilience.