scholarly journals A Small RNA-Based Immune System Defends Germ Cells against Mobile Genetic Elements

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Astrid D. Haase
Keyword(s):  
Immune System ◽  
Germ Cells ◽  
Mobile Genetic Elements ◽  
Short Review ◽  
Loss Of Function ◽  
Adaptation Mechanism ◽  
Genetic Elements ◽  
Small Regulatory Rna ◽  
Rna Pathways ◽  
Transposon Activity

Transposons are mobile genetic elements that threaten the survival of species by destabilizing the germline genomes. Limiting the spread of these selfish elements is imperative. Germ cells employ specialized small regulatory RNA pathways to restrain transposon activity. PIWI proteins and Piwi-interacting RNAs (piRNAs) silence transposons at the transcriptional and posttranscriptional level with loss-of-function mutant animals universally exhibiting sterility often associated with germ cell defects. This short review aims to illustrate basic strategies of piRNA-guided defense against transposons. Mechanisms of piRNA silencing are most readily studied inDrosophila melanogaster, which serves as a model to delineate molecular concepts and as a reference for mammalian piRNA systems. PiRNA pathways utilize two major strategies to handle the challenges of transposon control: (1) the hard-wired molecular memory of prior transpositions enables recognition of mobile genetic elements and discriminates transposons from host genes; (2) a feed-forward adaptation mechanism shapes piRNA populations to selectively combat the immediate threat of transposon transcripts. In flies, maternally contributed PIWI-piRNA complexes bolster both of these lines of defense and ensure transgenerational immunity. While recent studies have provided a conceptual framework of what could be viewed as an ancient immune system, we are just beginning to appreciate its many molecular innovations.

scholarly journals How important is CRISPR-Cas for protecting natural populations of bacteria against infections by mobile genetic elements?

2020 ◽  
Author(s):  
Edze Westra ◽  
Bruce Levin
Keyword(s):  
Computer Simulation ◽  
Immune System ◽  
Natural Populations ◽  
Adaptive Immune System ◽  
Simulation Models ◽  
Mobile Genetic Elements ◽  
Genetic Elements ◽  
Adaptive Immune ◽  
Computer Simulation Models

AbstractArticles on CRISPR commonly open with some variant of the phrase ‘these short-palindromic repeats and their associated endonucleases (Cas) are an adaptive immune system that exists to protect bacteria and archaea from viruses and infections with other mobile genetic elements’. There is an abundance of genomic data consistent with the hypothesis that CRISPR plays this role in natural populations of bacteria and archaea, and experimental demonstrations with a few species of bacteria and their phage and plasmids show that CRISPR-Cas systems can play this role in vitro. Not at all clear are the ubiquity, magnitude and nature of the contribution of CRISPR-Cas systems to the ecology and evolution of natural populations of microbes, and the strength of selection mediated by different types of phage and plasmids to the evolution and maintenance of CRISPR-Cas systems. In this perspective, with the aid of heuristic mathematical-computer simulation models, we explore the a priori conditions under which exposure to lytic and temperate phage and conjugative plasmids will select for and maintain CRISPR-Cas systems in populations of bacteria and archaea. We review the existing literature addressing these ecological and evolutionary questions and highlight the experimental and other evidence needed to fully understand the conditions responsible for the evolution and maintenance of CRISPR-Cas systems and the contribution of these systems to the ecology and evolution of bacteria, archaea and the mobile genetic elements that infect them.SignificanceThere is no question about the importance and utility of CRISPR-Cas for editing and modifying genomes. On the other hand, the mechanisms responsible for the evolution and maintenance of these systems and the magnitude of their importance to the ecology and evolution of bacteria, archaea and their infectious DNAs, are not at all clear. With the aid of heuristic mathematical – computer simulation models and reviews of the existing literature, we raise questions that have to be answered to elucidate the contribution of selection – mediated by phage and plasmids – to the evolution and maintenance of this adaptive immune system and its consequences for the ecology and evolution of prokaryotes and their viruses and plasmids.

scholarly journals Factors Regulating the Activity of LINE1 Retrotransposons

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1562
Author(s):  
Maria Sergeevna Protasova ◽  
Tatiana Vladimirovna Andreeva ◽  
Evgeny Ivanovich Rogaev
Keyword(s):  
Autoimmune Diseases ◽  
Germ Cells ◽  
Molecular Genetic ◽  
Mobile Genetic Elements ◽  
Regulation System ◽  
Epigenetic Changes ◽  
Genetic Elements ◽  
Genetic Mechanisms ◽  
Evolutionary Aspects ◽  
Host Regulation

LINE-1 (L1) is a class of autonomous mobile genetic elements that form somatic mosaicisms in various tissues of the organism. The activity of L1 retrotransposons is strictly controlled by many factors in somatic and germ cells at all stages of ontogenesis. Alteration of L1 activity was noted in a number of diseases: in neuropsychiatric and autoimmune diseases, as well as in various forms of cancer. Altered activity of L1 retrotransposons for some pathologies is associated with epigenetic changes and defects in the genes involved in their repression. This review discusses the molecular genetic mechanisms of the retrotransposition and regulation of the activity of L1 elements. The contribution of various factors controlling the expression and distribution of L1 elements in the genome occurs at all stages of the retrotransposition. The regulation of L1 elements at the transcriptional, post-transcriptional and integration into the genome stages is described in detail. Finally, this review also focuses on the evolutionary aspects of L1 accumulation and their interplay with the host regulation system.

scholarly journals The Staphylococcus aureus CC398 Lineage: An Evolution Driven by the Acquisition of Prophages and Other Mobile Genetic Elements

Genes ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1752
Author(s):  
Floriane Laumay ◽  
Hugo Benchetrit ◽  
Anna-Rita Corvaglia ◽  
Nathalie van der Mee-Marquet ◽  
Patrice François
Keyword(s):  
Staphylococcus Aureus ◽  
Large Scale ◽  
Clonal Complex ◽  
Hospital Setting ◽  
Mobile Genetic Elements ◽  
Short Review ◽  
Farm Animals ◽  
Current Evidence ◽  
Genetic Elements ◽  
Severe Infections

Among clinically relevant lineages of Staphylococcus aureus, the lineage or clonal complex 398 (CC398) is of particular interest. Strains from this lineage were only described as livestock colonizers until 2007. Progressively, cases of infection were reported in humans in contact with farm animals, and now, CC398 isolates are increasingly identified as the cause of severe infections even in patients without any contact with animals. These observations suggest that CC398 isolates have spread not only in the community but also in the hospital setting. In addition, several recent studies have reported that CC398 strains are evolving towards increased virulence and antibiotic resistance. Identification of the origin and emergence of this clonal complex could probably benefit future large-scale studies that aim to detect sources of contamination and infection. Current evidence indicates that the evolution of CC398 strains towards these phenotypes has been driven by the acquisition of prophages and other mobile genetic elements. In this short review, we summarize the main knowledge of this major lineage of S. aureus that has become predominant in the human clinic worldwide within a single decade.

Transgenesis of schistosomes: approaches employing mobile genetic elements

Parasitology ◽  
2007 ◽  
Vol 135 (2) ◽  
pp. 141-153 ◽  
Author(s):  
V. H. MANN ◽  
M. E. MORALES ◽  
K. J. KINES ◽  
P. J. BRINDLEY
Keyword(s):  
Large Scale ◽  
Insertional Mutagenesis ◽  
Genetic Manipulation ◽  
Draft Genome ◽  
Mobile Genetic Elements ◽  
Forward Genetics ◽  
Loss Of Function ◽  
Genetic Elements ◽  
The Past ◽  
Foreign Genes

SUMMARYDraft genome sequences forSchistosoma mansoniandSchistosoma japonicumare now available. However, the identity and importance of most schistosome genes have yet to be determined. Recently, progress has been made towards the genetic manipulation and transgenesis of schistosomes. Both loss-of-function and gain-of-function approaches appear to be feasible in schistosomes based on findings described in the past 5 years. This review focuses on reports of schistosome transgenesis, specifically those dealing with the transformation of schistosomes with exogenous mobile genetic elements and/or their endogenous relatives for the genetic manipulation of schistosomes. Transgenesis mediated by mobile genetic elements offers a potentially tractable route to introduce foreign genes to schistosomes, a means to determine the importance of schistosome genes, including those that could be targeted in novel interventions and the potential to undertake large-scale forward genetics by insertional mutagenesis.

ISSR-PCR markers and mobile genetic elements in horse (Equus caballus) genome

2014 ◽  
pp. 42-57 ◽  
Author(s):  
N.V. Bardukov ◽  
◽  
A.V. Feofilov ◽  
T.T. Glazko ◽  
V.I. Glazko ◽  
...  
Keyword(s):  
Equus Caballus ◽  
Mobile Genetic Elements ◽  
Pcr Markers ◽  
Genetic Elements ◽  
Issr Pcr

Potential immunotherapy for Alzheimer disease and age-related dementia

2019 ◽  
Vol 21 (1) ◽  
pp. 21-25 ◽  
Keyword(s):  
Immune System ◽  
Alzheimer Disease ◽  
Cross Talk ◽  
Immune Checkpoint ◽  
Short Review ◽  
Immune Checkpoint Blockade ◽  
Checkpoint Blockade ◽  
New Approach ◽  
Age Related ◽  
The Brain

Emerging results support the concept that Alzheimer disease (AD) and age-related dementia are affected by the ability of the immune system to contain the brain's pathology. Accordingly, well-controlled boosting, rather than suppression of systemic immunity, has been suggested as a new approach to modify disease pathology without directly targeting any of the brain's disease hallmarks. Here, we provide a short review of the mechanisms orchestrating the cross-talk between the brain and the immune system. We then discuss how immune checkpoint blockade directed against the PD-1/PD-L1 pathways could be developed as an immunotherapeutic approach to combat this disease using a regimen that will address the needs to combat AD.

Potential immunotherapy for Alzheimer disease and age-related dementia

2019 ◽  
Vol 21 (1) ◽  
pp. 21-25 ◽  
Keyword(s):  
Immune System ◽  
Alzheimer Disease ◽  
Cross Talk ◽  
Immune Checkpoint ◽  
Short Review ◽  
Immune Checkpoint Blockade ◽  
Checkpoint Blockade ◽  
New Approach ◽  
Age Related ◽  
The Brain

Emerging results support the concept that Alzheimer disease (AD) and age-related dementia are affected by the ability of the immune system to contain the brain’s pathology. Accordingly, well-controlled boosting, rather than suppression of systemic immunity, has been suggested as a new approach to modify disease pathology without directly targeting any of the brain’s disease hallmarks. Here, we provide a short review of the mechanisms orchestrating the cross-talk between the brain and the immune system. We then discuss how immune checkpoint blockade directed against the PD-1/PD-L1 pathways could be developed as an immunotherapeutic approach to combat this disease using a regimen that will address the needs to combat AD.

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