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Neurofibromatosis Types 1 and 2
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Cell growth within the mammalian body is typically controlled by two main types of genes, proto-oncogenes and tumor suppressor genes. While a functional proto-oncogene helps cells grow and divide, a mutated proto-oncogene (or presence of extra copies due to gene duplication) becomes an oncogene (which is permanently activated or turned on), resulting in uncontrolled cell growth and tumorigenesis. On the other hand, a functional tumor suppressor gene keeps the cell from dividing too quickly, repairs DNA mistakes, and induces programmed cell death (apoptosis); a mutated tumor suppressor gene becomes inactivated (turned off), rendering cell growth/division out of control, and facilitating cancer development (tumor suppressor syndrome).
Mobile DNA Sequences and Their Possible Role in Evolution
Published in S. K. Dutta, DNA Systematics, 2019
Georgii P. Georgiev, Yurii V. Ilyin, Alexei P. Ryskov, Tatiana I. Gerasimova
Finally, the movable elements may become the sites of unequal crossing over that can lead to the tandem duplication of genetic material.160 In several cases, gene duplication may have proceeded in this way.
Notes on Cancer
Published in Nate F. Cardarelli, The Thymus in Health and Senescence, 2019
There is no scarcity of theories as to why cancer occurs, nor is there a consensus in detail. For our purposes, it will be sufficient to provide the reader with a synopsis of several important papers. It is well accepted that some sort of agent acts as a carcinogen. Pullman and Pullman hypothesized that there must be a chemical reaction between the carcinogen and its cell receptor.62 Thus, there had to be certain reactive sites on the carcinogen that could combine with the receptor. Therefore by noting the molecular configuration of a given material, one could predict its cancer causing potential. A few years later Potter suggested that cancer arises from an inherent error in gene duplication, cancer being an “evolutionary process along a dead end street”.63 He correctly surmised that “we can understand cancer only to the extent that we understand life”.
Modern approaches for the phenotyping of cytochrome P450 enzymes in children
Published in Expert Review of Clinical Pharmacology, 2020
CYP450 genotyping, including copy-number-variation analysis, is extensively used in clinical settings. It allows the identification of single nucleotide polymorphisms, gene deletion and gene duplication or multiplication. It requires DNA extraction from buccal swabs, saliva or blood and is therefore easily applicable in pediatrics. When available, it is then possible to translate the genotype of an isoenzyme into a phenotype using a standardized method as developed, for example, for the CYP2D6 enzyme by the Clinical Pharmacogenetics Implementation Consortium and Dutch Pharmacogenetics Working Group [4]. Less standardized systems for translating genotype into phenotype also exist for CYP2B6, CYP2C9, CYP2C19 and CYP3A5 [4]. However, phenotype-genotype relationships are poorly described for CYP1A2 and CYP3A4 [3]. In addition, genotyping does not take into account the influence of environmental factors such as concomitant medication or smoking on the enzymatic activity. For these reasons, CYP450 phenotyping (i.e. real-time measurement of CYP450 activity) is therefore preferred to genotyping. In addition, it allows the evolution of these enzymes over time and age to be captured [2,5].
Hematopoietic growth factors: the scenario in zebrafish
Published in Growth Factors, 2018
Vahid Pazhakh, Graham J. Lieschke
Gene duplication, not least in part the legacy of a whole genome duplication in the teleost radiation, has left its legacy on the zebrafish genome (Braasch et al., 2016; Postlethwait et al., 1998). While gene duplication can be considered to be an added complexity, it has also provided nature with an opportunity to explore biologically feasible variations that can provide biological insight when they are understood. Diversification processes including gene loss, subfunctionalization and neofunctionalization can eliminate or segregate biological functions between duplicates, or assign new functions to individual duplicates. These processes can create new private single ligand/receptor pairs, or regionally isolate components of promiscuous ligand/receptor groups to achieve highly specific anatomically-localized effects. Amongst model organisms, zebrafish are not unique in the diversity of their HGF ligand/receptor configurations: even between humans and mice, significant differences exist. For example, interleukin-3 receptor structure is more complex in the mouse than human, there being an extra mouse-specific alternative beta subunit (Geijsen et al., 2001; Hara & Miyajima, 1992).
Serine-rich repeat proteins from gut microbes
Published in Gut Microbes, 2020
Dimitrios Latousakis, Donald A. MacKenzie, Andrea Telatin, Nathalie Juge
The glycosylation profile of SRRPs from L. reuteri was recently determined using a combination of bioinformatics analysis, lectin screening, LC-MS-based sugar nucleotide profiling, MALDI-ToF, and GC-MS analyses. This study showed that the L. reuteri ATCC 53608 and 100-23C strains were capable of performing protein glycosylation and that SRRP100-23 and SRRP53608 were glycosylated with Hex-Hex-HexNAc and di-HexNAc moieties, respectively. Following in vivo glycoengineering in E. coli, NMR analysis and enzymatic treatment further showed that SRRP53608 was glycosylated with GlcNAcβ(1→6)-GlcNAcα moieties. Together, it was suggested that SRRP100-23 is glycosylated with GlcNAc and Hex-Glc-GlcNAc whereas SRRP53608 is glycosylated with GlcNAc and di-GlcNAc moieties15 (Figure 4) (Table 1). Although both strains encode a predicted Asp2, O-acetylation could not be confirmed biochemically due to the conditions used in the MS analysis.15 The number of GTs in the L. reuteri 100-23C SecA2/Y2 cluster exceeds the number of sugars on SRRP100-23, as also reported for some streptococcal SecA2/Y2 systems.14,45 To date, there is no generic explanation for the presence of additional genes encoding GTs in the genomes of these strains. In some cases, gene duplication is observed, which may lead to functional redundancy, whereas insertion of genetic elements into genes encoding GTs may lead to gene inactivation. A defective glycosylation of SRRPs in pathogenic bacteria led to impaired binding of the respective bacteria onto model substrates and reduced virulence in mouse models.1,55,56 The glycosylation of SRRPs in Lactobacillus species, as demonstrated for L. reuteri strains, is likely to impact on the adhesion capacity of these strains.