China
Africa
Explore chapters and articles related to this topic
Genetic Regulation of Principal Microorganisms (Yeast, Zymomonas mobilis, and Clostridium thermocellum) Producing Bioethanol/Biofuel
Published in Ayerim Y. Hernández Almanza, Nagamani Balagurusamy, Héctor Ruiz Leza, Cristóbal N. Aguilar, Bioethanol, 2023
Dania Sandoval-Nuñez, Teresa Romero-Gutiérrez, Melchor Arellano-Plaza, Anne Gschaedler, Lorena Amaya-Delgado
Gene regulation is a cellular process consisting of activating or deactivating genes, which can occur at any point in the transcription-translation process. Gene regulation occurs most frequently at the transcriptional level. The regulation of gene expression in yeast can take place in different stages (Figure 4.1). In the nucleus, the chromatin remodeling process regulates the availability of a gene for transcription. Once transcribed, the primary mRNA transcript, or pre-mRNA, undergoes RNA processing, which involves splicing and adding a 5’ cap and 3’ poly (A) tail to produce a mature mRNA in the nucleus. Mature mRNA is exported from the nucleus to the cytoplasm, where its lifespan varies. Outside the nucleus, localization factors can direct mature mRNAs to specific regions of the cytoplasm where they are translated into polypeptides. The resulting polypeptides can undergo posttranslational modifications, which can regulate protein folding, glycosylation, intracellular transport, and protein activation and degradation.
Genome Editing and Gene Therapies: Complex and Expensive Drugs
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2020
One important application of the CRISPR/Cas system is the CRISPR/dCas9-mediated epigenome editing enabling insight into histone post-translational modifications, non-coding RNAs, and others, responsible for the organization of chromatin structure and epigenetic regulation; it provides information into the role epigenetic regulation has in connection with developing diseases and other biological phenomena (Xie et al., 2018; Enríquez, 2016). For this purpose dCas9 is fused to an epieffector which results in activation (e.g., acetylation of histone lysine residues) or repression (transfer of methyl or removal of acetyl groups from histone residues). An example of an activation has been described by Hilton et al. (2015), who generated an effector fusion protein of dCas9 and the catalytic core of the human acetyltransferase p300 that catalyzed acetylation of histone H3 lysine 27 associated with transcriptional activation of genes from promoters and enhancers (see also Chapter 11).
Genes and Genomics
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
Chromatin is the complex combination of DNA, RNA, and protein that makes up chromosomes. It is found inside the nuclei in eukaryotic cells, and within the nucleoid in prokaryotic cells. It is divided between heterochromatin (condensed) and euchromatin (extended) forms. The major components of chromatin are DNA and histone proteins, although many other chromosomal proteins have prominent roles too. The functions of chromatin are to package DNA into a smaller volume to fit in the cell, to strengthen the DNA to allow mitosis and meiosis, and to serve as a mechanism to control expression and DNA replication. Chromatin contains genetic material instructions to direct cell functions. Changes in chromatin structure are affected by chemical modifications of histone proteins such as methylation (DNA and proteins) and acetylation (proteins), and by non-histone DNA-binding proteins.
The interplay between DNA methylation and cardiac autonomic system functioning: a systematic review
Published in International Journal of Environmental Health Research, 2023
Nayara Cristina Dos Santos Oliveira, Fernanda Serpeloni, Simone Gonçalves de Assis
Epigenetics refers to a dynamic and biological phenomenon that may be heritable and sensitive to environmental factors, which appears to influence the cardiovascular autonomic regulation (Figure 1). Epigenetic mechanisms involve modifications of histone proteins and non-coding RNAs, including microRNAs and DNAm, which regulate gene expression profiles without altering the DNA sequence but instead through chromatin reorganization (Allis and Jenuwein 2016). This review focuses on the DNAm because it has been linked to several cardiovascular-related biomarkers (Baccarelli et al. 2010; Rosa-Garrido et al. 2018). DNAm is the addition of a methyl group to the 5′ position of cytosine in CpG dinucleotides (CpGs), at promoters and other regions (Jones 2012). Patients with atherosclerotic cardiovascular disease, for instance, exhibited lower global DNAm status in peripheral blood leukocytes (Castro et al. 2003).
Benzo[a]pyrene osteotoxicity and the regulatory roles of genetic and epigenetic factors: A review
Published in Critical Reviews in Environmental Science and Technology, 2022
Jiezhang Mo, Doris Wai-Ting Au, Jiahua Guo, Christoph Winkler, Richard Yuen-Chong Kong, Frauke Seemann
Histone modification can also regulate gene expression epigenetically. Notably, DNA is complexed with histones, which results in its compaction and assembly into nucleosomes of the chromatin. Histone modifications are heavily involved in the regulation of gene transcription, DNA replication and DNA repair, and modifications that occur on accessible histone tails, which regulate the chromatin structure (Bártová et al., 2008). In addition to well-characterized histone modifications, including acetylation, methylation, phosphorylation, and ubiquitylation modification (Lennartsson & Ekwall, 2009), recent studies have identified new types of histone modifications, such as propionylation, butyrylation, malonylation and glycosylation (Wang et al., 2019). Specifically, histone acetyltransferases (HATs) and histone deacetylases (HDACs) are responsible for the acetylation and deacetylation of histones, respectively (Lennartsson & Ekwall, 2009). The deacetylation of histones (hyperacetylated histones) leads to uncompressed chromatin and increased accessibility of DNA binding, which facilitates gene transcription. In contrast, the acetylation of histones (hypoacetylated histones) results in condensed chromatin and transcription repression. Additionally, the methylation and demethylation of histones are catalyzed by lysine methyltransferases and arginine methyltransferases, respectively (Bártová et al., 2008).
Development of a database on key characteristics of human carcinogens
Published in Journal of Toxicology and Environmental Health, Part B, 2019
Mustafa Al-Zoughool, Michael Bird, Jerry Rice, Robert A. Baan, Mélissa Billard, Nicholas Birkett, Daniel Krewski, Jan M Zielinski
Cancer risk may vary at different life stages. Exposures to exogenous agents might elicit different types and levels of adverse responses according to the age of the exposed individual. This may be related to different levels of exposure: the risk of ovarian cancer, for example, varies in response to reproductive characteristics such as hormone use and menopausal status (Moorman et al. 2008). In other cases, the risk of cancer occurrence may vary as a result of age-related changes in cellular structure or function. Das and Tyler (2013) noted the functioning of the chromatin apparatus appeared to change during aging, which might lead to alterations in genomic functions such as transcription and replication. DNA repair is another molecular process that decreases in effectiveness with age (Garm et al. 2013).