RESUMO
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.
Assuntos
Histonas , Defeitos do Tubo Neural , Animais , Humanos , Histonas/metabolismo , Código das Histonas , Defeitos do Tubo Neural/genética , Epigênese Genética , Metilação de DNARESUMO
Since Late-onset Alzheimer's disease (LOAD) derives from a combination of genetic variants and environmental factors, epigenetic modifications have been predicted to play a role in the etiopathology of LOAD. Along with DNA methylation, histone modifications have been proposed as the main epigenetic modifications that contribute to the pathologic mechanisms of LOAD; however, little is known about how these mechanisms contribute to the disease's onset or progression. In this review, we highlighted the main histone modifications and their functional role, including histone acetylation, histone methylation, and histone phosphorylation, as well as changes in such histone modifications that occur in the aging process and mainly in Alzheimer's disease (AD). Furthermore, we pointed out the main epigenetic drugs tested for AD treatment, such as those based on histone deacetylase (HDAC) inhibitors. Finally, we remarked on the perspectives around the use of such epigenetics drugs for treating AD.
Assuntos
Doença de Alzheimer , Humanos , Doença de Alzheimer/genética , Histonas/genética , Código das Histonas , Metilação de DNA , Epigênese Genética , Inibidores de Histona Desacetilases/farmacologiaRESUMO
Post-translational modifications (PTMs) have a strong impact on many proteins across all kingdoms of life, affecting multiple functional and chemical properties of their protein recipients. With increasing knowledge about their functions, targets, and biological effects, dysregulations in PTMs have been implicated in various dysfunctions and diseases. One such target are histones, which compose the majority of the protein component of chromatin and the modulation of the 30+ PTMs that are known to affect them can have profound effects on chromatin state, gene expression, and DNA repair. In this review, the histone targets of PTMs are compiled in the context of neurological disorders, highlighting their specific biological roles and any previously implicated dysregulations in several classes of brain disease. Better understanding the pathogenic dysregulations of PTMs in such disorders can help to better understand their causes, as well as open doors to new possibilities for biomarkers and therapeutic targets.
Assuntos
Encefalopatias , Código das Histonas , Cromatina , Histonas , Humanos , Processamento de Proteína Pós-TraducionalRESUMO
Parathyroid tumors are very prevalent conditions among endocrine tumors, being the second most common behind thyroid tumors. Secondary hyperplasia can occur beyond benign and malignant neoplasia in parathyroid glands. Adenomas are the leading cause of hyperparathyroidism, while carcinomas represent less than 1% of the cases. Tumor suppressor gene mutations such as MEN1 and CDC73 were demonstrated to be involved in tumor development in both familiar and sporadic types; however, the epigenetic features of the parathyroid tumors are still a little-explored subject. We present a review of epigenetic mechanisms related to parathyroid tumors, emphasizing advances in histone modification and its perspective of becoming a promising area in parathyroid tumor research.
Assuntos
Hiperparatireoidismo , Neoplasias das Paratireoides , Epigênese Genética , Epigenômica , Código das Histonas/genética , Humanos , Hiperparatireoidismo/genética , Neoplasias das Paratireoides/genéticaRESUMO
Invasive Pulmonary Aspergillosis, which is caused by the filamentous fungus Aspergillus fumigatus, is a life-threatening infection for immunosuppressed patients. Chromatin structure regulation is important for genome stability maintenance and has the potential to drive genome rearrangements and affect virulence and pathogenesis of pathogens. Here, we performed the first A. fumigatus global chromatin profiling of two histone modifications, H3K4me3 and H3K9me3, focusing on the two most investigated A. fumigatus clinical isolates, Af293 and CEA17. In eukaryotes, H3K4me3 is associated with active transcription, while H3K9me3 often marks silent genes, DNA repeats, and transposons. We found that H3K4me3 deposition is similar between the two isolates, while H3K9me3 is more variable and does not always represent transcriptional silencing. Our work uncovered striking differences in the number, locations, and expression of transposable elements between Af293 and CEA17, and the differences are correlated with H3K9me3 modifications and higher genomic variations among strains of Af293 background. Moreover, we further showed that the Af293 strains from different laboratories actually differ in their genome contents and found a frequently lost region in chromosome VIII. For one such Af293 variant, we identified the chromosomal changes and demonstrated their impacts on its secondary metabolites production, growth and virulence. Overall, our findings not only emphasize the influence of genome heterogeneity on A. fumigatus fitness, but also caution about unnoticed chromosomal variations among common laboratory strains.
Assuntos
Aspergillus fumigatus/classificação , Cromossomos Fúngicos/genética , Heterogeneidade Genética , Histonas/metabolismo , Aspergilose Pulmonar/microbiologia , Aspergillus fumigatus/genética , Aspergillus fumigatus/isolamento & purificação , Cromatina , Elementos de DNA Transponíveis , Proteínas Fúngicas/metabolismo , Regulação da Expressão Gênica de Plantas , Aptidão Genética , Código das Histonas , Humanos , Regiões Promotoras Genéticas , Metabolismo Secundário , VirulênciaRESUMO
Epigenetic mechanisms, such as DNA methylation, histone modifications, and non-coding RNAs are known regulators of gene expression and genomic stability in cell growth, development, and differentiation. Because epigenetic mechanisms can regulate several immune system elements, epigenetic alterations have been found in several autoimmune diseases. The purpose of this review is to discuss the epigenetic modifications, mainly DNA methylation, involved in autoimmune diseases in which T cells play a significant role. For example, Rheumatoid Arthritis and Systemic Lupus Erythematosus display differential gene methylation, mostly hypomethylated 5'-C-phosphate-G-3' (CpG) sites that may associate with disease activity. However, a clear association between DNA methylation, gene expression, and disease pathogenesis must be demonstrated. A better understanding of the impact of epigenetic modifications on the onset of autoimmunity will contribute to the design of novel therapeutic approaches for these diseases.
Assuntos
Doenças Autoimunes/patologia , Metilação de DNA , Epigênese Genética , Predisposição Genética para Doença , Código das Histonas , Animais , Doenças Autoimunes/etiologia , HumanosRESUMO
Emerging evidence indicates the clinical benefits of photobiomodulation therapy (PBMT) in the management of skin and mucosal wounds. Here, we decided to explore the effects of different regiments of PBMT on epithelial cells and stem cells, and the potential implications over the epigenetic circuitry during healing. Scratch-wound migration, immunofluorescence (anti-acetyl-Histone H3, anti-acetyl-CBP/p300 and anti-BMI1), nuclear morphometry and western blotting (anti-Phospho-S6, anti-methyl-CpG binding domain protein 2 [MBD2]) were performed. Epithelial stem cells were identified by the aldehyde dehydrogenase enzymatic levels and sphere-forming assay. We observed that PBMT-induced accelerated epithelial migration and chromatin relaxation along with increased levels of histones acetylation, the transcription cofactors CBP/p300 and mammalian target of rapamycin. We further observed a reduction of the transcription repression-associated protein MBD2 and a reduced number of epithelial stem cells and spheres. In this study, we showed that PBMT could induce epigenetic modifications of epithelial cells and control stem cell fate, leading to an accelerated healing phenotype.
Assuntos
Terapia com Luz de Baixa Intensidade , Acetilação , Epigênese Genética , Código das Histonas , Células-Tronco , CicatrizaçãoRESUMO
DNA methyltransferases (DNMTs) play an essential role in DNA methylation and transcriptional regulation in the genome. DNMTs, along with other poorly studied elements, modulate the dynamic DNA methylation patterns of embryonic and adult cells. We summarize the current knowledge on the molecular mechanism of DNMTs' functional targeting to maintain genome-wide DNA methylation patterns. We focus on DNMTs' intrinsic characteristics, transcriptional regulation, and post-transcriptional modifications. Furthermore, we focus special attention on the DNMTs' specificity for target sites, including key cis-regulatory factors such as CpG content, common motifs, transcription factors (TF) binding sites, lncRNAs, and histone marks to regulate DNA methylation. We also review how complexes of DNMTs/TFs or DNMTs/lncRNAs are involved in DNA methylation in specific genome regions. Understanding these processes is essential because the spatiotemporal regulation of DNA methylation modulates gene expression in health and disease.
Assuntos
Metilação de DNA , Metilases de Modificação do DNA/genética , Código das Histonas/genética , RNA Longo não Codificante/genética , Fatores de Transcrição/genética , 5-Metilcitosina/metabolismo , Animais , Ilhas de CpG , DNA (Citosina-5-)-Metiltransferase 1/genética , DNA (Citosina-5-)-Metiltransferase 1/metabolismo , Metilases de Modificação do DNA/metabolismo , Humanos , Regiões Promotoras GenéticasRESUMO
Scientific advances in recent decades have revealed an incredible degree of plasticity in gene expression in response to various environmental, nutritional, physiological, pathological, and behavioral conditions. Epigenetics emerges in this sense, as the link between the internal (genetic) and external (environmental) factors underlying the expression of the phenotype. Methylation of DNA and histone post-translationa modifications are canonical epigenetic events. Additionally, noncoding RNAs molecules (microRNAs and lncRNAs) have also been proposed as another layer of epigenetic regulation. Together, these events are responsible for regulating gene expression throughout life, controlling cellular fate in both normal and pathological development. Despite being a relatively recent science, epigenetics has been arousing the interest of researchers from different segments of the life sciences and the general public. This review highlights the recent advances in the characterization of the epigenetic events and points promising use of these brands for the diagnosis, prognosis, and therapy of diseases. We also present several classes of epigenetic modifying compounds with therapeutic applications (so-call epidrugs) and their current status in clinical trials and approved by the FDA. In summary, hopefully, we provide the reader with theoretical bases for a better understanding of the epigenetic mechanisms and of the promising application of these marks and events in the medical clinic.
Assuntos
Biomarcadores/metabolismo , Metilação de DNA , Desenvolvimento de Medicamentos/métodos , Epigênese Genética , Código das Histonas , Animais , Regulação da Expressão Gênica , Humanos , MicroRNAs/genética , RNA Longo não Codificante/genéticaRESUMO
BACKGROUND: We have previously developed a murine cellular system that models the transformation from melanocytes to metastatic melanoma cells. This model was established by cycles of anchorage impediment of melanocytes and consists of four cell lines: differentiated melanocytes (melan-a), pre-malignant melanocytes (4C), malignant (4C11-), and metastasis-prone (4C11+) melanoma cells. Here, we searched for transcriptional and epigenetic signatures associated with melanoma progression and metastasis by performing a gene co-expression analysis of transcriptome data and a mass-spectrometry-based profiling of histone modifications in this model. RESULTS: Eighteen modules of co-expressed genes were identified, and some of them were associated with melanoma progression, epithelial-to-mesenchymal transition (EMT), and metastasis. The genes in these modules participate in biological processes like focal adhesion, cell migration, extracellular matrix organization, endocytosis, cell cycle, DNA repair, protein ubiquitination, and autophagy. Modules and hub signatures related to EMT and metastasis (turquoise, green yellow, and yellow) were significantly enriched in genes associated to patient survival in two independent melanoma cohorts (TCGA and Leeds), suggesting they could be sources of novel prognostic biomarkers. Clusters of histone modifications were also linked to melanoma progression, EMT, and metastasis. Reduced levels of H4K5ac and H4K8ac marks were seen in the pre-malignant and tumorigenic cell lines, whereas the methylation patterns of H3K4, H3K56, and H4K20 were related to EMT. Moreover, the metastatic 4C11+ cell line showed higher H3K9me2 and H3K36me3 methylation, lower H3K18me1, H3K23me1, H3K79me2, and H3K36me2 marks and, in agreement, downregulation of the H3K36me2 methyltransferase Nsd1. CONCLUSIONS: We uncovered transcriptional and histone modification signatures that may be molecular events driving melanoma progression and metastasis, which can aid in the identification of novel prognostic genes and drug targets for treating the disease.