Cellular and Viral Oncogenes
Pimentel Enrique in Oncogenes, 2020
The existence of a number of structural cellular genes, termed Tr genes, whose unscheduled activation would lead to neoplasia was discussed later as a general theory of carcinogenesis.4 The Tr genes would be involved in the normal control of growth but would code for products with transforming potential and would be contained in all cells of the multicellular organisms. These genes would normally be active during embryogenesis, being specifically repressed thereafter in particular tissues by the action of regulatory genes. Spontaneous tumors, or tumors induced by chemicals or radiation, would arise as the result of mutation of regulatory genes releasing the suppression of the corresponding Tr genes and leading to transformation. According to the same hypothesis, oncogenic viruses evolved by the extraction of host Tr genes with their conversion to viral transforming genes. Moreover, the reintroduction of Tr genes into susceptible cells would produce their malignant transformation. The Tr genes remained, however, uncharacterized.
Introduction
James F. Kane in Multifunctional Proteins: Catalytic/Structural and Regulatory, 2019
The elegant studies of Jacob and Monod1 on the lactose operon of Escherichia coli illustrated a simple yet effective means for the control of gene expression. In this system, the protein product of a regulatory gene, (i), binds to a region of the DNA called the operator locus (o). This protein prevents transcription of the structural genes of the lactose operon by the RNA polymerase that is bound to the DNA at a site called the promoter (p). This repressor protein, however, also possesses a binding site for a small molecule, namely β-allolactose. When β-allolactose binds to the repressor protein the protein-allolactose complex no longer interacts with the operator region of the DNA and the structural genes of the lactose operon are transcribed into mRNA by the RNA polymerase. This type of control is called induction and the “i” gene product is called a negative effector because it functions only in stopping synthesis of mRNA from the DNA. Subsequent studies have shown that the regulation of the lactose operon is more complex and involves cyclic AMP and a cyclic AMP binding protein.2 These latter elements are essential for the efficient transcription of the lactose operon by RNA polymerase and are, therefore, called positive regulatory elements. Despite this added level of complexity the role of the lactose repressor protein remains unchanged from the original description of its function by Jacob and Monod. That is, its sole function is the negative control, or turning off, of the transcription of the lactose operon. In this case, the regulatory gene “i” is itself constitutively expressed: that is, its expression is not regulated.3
HIV-1: Biology
Niel T. Constantine, Johnny D. Callahan, Douglas M. Watts in Retroviral Testing, 2020
The genome of HIV contains two types of genes: the structural genes and the regulatory genes. The structural genes are responsible for the direction and synthesis of proteins and glycoproteins that will give the virus its physical characteristics; i.e., shape, size, structural integrity, compartmentalization, etc. The regulatory genes are responsible for the subsequent production of proteins that can affect the activities of viral components, or can specifically turn other genes on and off. Among other activities, the regulatory proteins have the ability to increase or decrease the replication of HIV. It is probable that the activity of these regulatory genes is responsible for the profound pathogenicity of HIV.
Exposure to Al2O3 nanoparticles facilitates conjugative transfer of antibiotic resistance genes from Escherichia coli to Streptomyces
Published in Nanotoxicology, 2019
Xiaomei Liu, Jingchun Tang, Benru Song, Meinan Zhen, Lan Wang, John P. Giesy
Seven genes were chosen to verify whether the addition of NPs affects the expression of genes related to conjugative transfer. OmpC porin was known to play important roles in the membrane transport of genetic information between cells and the environment (Ozkanca et al. 2002). Results showed that the expression of ompC was increased after exposure to NPs (Figure 6(A)). And the expression levels of three global regulatory genes korA, korB, and trbA were significantly repressed (Figure 6(B–D)) after exposure compared to those of the control. The degree of gene inhibition was directly proportional to the concentration of NPs and was inversely proportional to particle size. Repression of the three global regulatory genes significantly promoted the expression of trbB and trfA (Figure 6(E,F)). And the expression of intA increased after exposure to NPs.
Comprehensive bioinformatics analysis reveals the hub genes and pathways associated with multiple myeloma
Published in Hematology, 2022
Shengli Zhao, Xiaoyi Mo, Zhenxing Wen, Lijuan Ren, Zhipeng Chen, Wei Lin, Qi Wang, Shaoxiong Min, Bailing Chen
Different from traditional research methods, the popularization and application of high-throughput sequencing and the establishment of a global gene database provide broader and necessary data support for the aetiological diagnosis of MM [9]. Meanwhile, the development of bioinformatics technology provides a reliable way to discover key regulatory genes of disease [10]. On this basis, an increasing number of MM-related genes and pathways have been discovered, and some of them have been proven to play an important role in the onset and progression of disease in subsequent validation [11–13]. However, these studies may have some defects while providing valuable information. On the one hand, the unstandardized heterogeneity of the data used may lead to the concealment of important genetic information, resulting in unreliable results. On the other hand, monotonous computer algorithms and unreasonable threshold settings may include many genes with low association with MM or exclude certain genes with small differential multiples but have an important functional role, which weakens the value of follow-up research based on these studies [14]. For these concerns, bioinformatics analysis for MM needs to be developed to a deeper and more comprehensive level.
Heterogeneity of T cells and macrophages in chlorine-induced acute lung injury in mice using single-cell RNA sequencing
Published in Inhalation Toxicology, 2022
Chen-qian Zhao, Jiang-zheng Liu, Meng-meng Liu, Xiao-ting Ren, De-qin Kong, Jie Peng, Meng Cao, Rui Liu, Chun-xu Hai, Xiao-di Zhang
Transcription factors (TFs) and their downstream regulatory genes constitute a complex and intertwined gene regulatory network, which determines and maintains cell characteristics. We performed SCENIC analysis to infer the activity of T-cell regulatory factors (a TF and its target gene together constitute a regulatory factor) (Figure 4(D)). Genes regulated by Ets1, Elf1, and Elk3 were highly upregulated in Cl2 exposure group, while genes regulated by Maf, Creb3l2, and Rara were upregulated in control group. Ets1 is a sequence-specific TF whose timely expression plays an important role in the evolution of the T and natural killer (NK) cell lineages (Cauchy et al. 2016). In in vivo studies, we also found a significant upregulation in Elk3 in the Cl2 exposure group (Figure 4(E)). These results demonstrated that T cells play a key role in the development of Cl2-induced ALI.
Related Knowledge Centers
- Directionality
- Gene Expression
- Microrna
- Regulatory Sequence
- Repressor
- Rna
- Rna Polymerase
- Gene
- Regulation of Gene Expression
- Translation