scholarly journals The birth of piRNAs: how mammalian piRNAs are produced, originated, and evolved

2021 ◽  
Author(s):  
Yu H. Sun ◽  
Brent Lee ◽  
Xin Zhiguo Li
Keyword(s):  
Small Rnas ◽  
Gene Expression Regulation ◽  
Epigenetic Modification ◽  
Developmental Regulation ◽  
Animal Evolution ◽  
Small Noncoding Rnas ◽  
Complex Process ◽  
Processing Pathways ◽  
Range Of Functions ◽  
Genomic Regions

AbstractPIWI-interacting RNAs (piRNAs), small noncoding RNAs 24–35 nucleotides long, are essential for animal fertility. They play critical roles in a range of functions, including transposable element suppression, gene expression regulation, imprinting, and viral defense. In mammals, piRNAs are the most abundant small RNAs in adult testes and the only small RNAs that direct epigenetic modification of chromatin in the nucleus. The production of piRNAs is a complex process from transcription to post-transcription, requiring unique machinery often distinct from the biogenesis of other RNAs. In mice, piRNA biogenesis occurs in specialized subcellular locations, involves dynamic developmental regulation, and displays sexual dimorphism. Furthermore, the genomic loci and sequences of piRNAs evolve much more rapidly than most of the genomic regions. Understanding piRNA biogenesis should reveal novel RNA regulations recognizing and processing piRNA precursors and the forces driving the gain and loss of piRNAs during animal evolution. Such findings may provide the basis for the development of engineered piRNAs capable of modulating epigenetic regulation, thereby offering possible single-dose RNA therapy without changing the genomic DNA. In this review, we focus on the biogenesis of piRNAs in mammalian adult testes that are derived from long non-coding RNAs. Although piRNA biogenesis is believed to be evolutionarily conserved from fruit flies to humans, recent studies argue for the existence of diverse, mammalian-specific RNA-processing pathways that convert precursor RNAs into piRNAs, perhaps associated with the unique features of mammalian piRNAs or germ cell development. We end with the discussion of major questions in the field, including substrate recognition and the birth of new piRNAs.

scholarly journals TET3 regulates DNA hydroxymethylation of neuroprotective genes following focal ischemia

2020 ◽  
pp. 0271678X2091296
Author(s):  
Kahlilia C Morris-Blanco ◽  
Anil K Chokkalla ◽  
Mario J Bertogliat ◽  
Raghu Vemuganti
Keyword(s):  
Epigenetic Modification ◽  
Infarct Volume ◽  
Focal Ischemia ◽  
Sequencing Analysis ◽  
Dependent Manner ◽  
Dna Hydroxymethylation ◽  
Adult Mice ◽  
Genome Wide ◽  
Endogenous Protection ◽  
Genomic Regions

The 5-hydroxymethylcytosine (5hmC) epigenetic modification is highly enriched in the CNS and a critical modulator of neuronal function and development. We found that cortical 5hmC was enhanced from 5 min to three days of reperfusion following focal ischemia in adult mice. Blockade of the 5hmC-producing enzyme ten-eleven translocase 3 (TET3) increased edema, infarct volume, and motor function impairments. To determine the mechanism by which TET3 provides ischemic neuroprotection, we assessed the genomic regions where TET3 modulates 5hmC. Genome-wide sequencing analysis of differentially hydroxymethylated regions (DhMRs) revealed that focal ischemia robustly increased 5hmC at the promoters of thousands of genes in a TET3-dependent manner. TET3 inhibition reduced 5hmC at the promoters of neuroprotective genes involved in cell survival, angiogenesis, neurogenesis, antioxidant defense, DNA repair, and metabolism demonstrating a role for TET3 in endogenous protection against stroke. The mRNA expression of several genes with known involvement in ischemic neuroprotection were also reduced with TET3 knockdown in both male and female mice, establishing a correlation between decreased promoter 5hmC levels and decreased gene expression. Collectively, our results indicate that TET3 globally increases 5hmC at regulatory regions and overwhelmingly modulates 5hmC in several neuroprotective pathways that may improve outcome after ischemic injury.

scholarly journals Small RNA molecules in the regulation of spermatogenesis

Reproduction ◽  
2009 ◽  
Vol 137 (6) ◽  
pp. 901-911 ◽  
Author(s):  
Zuping He ◽  
Maria Kokkinaki ◽  
Disha Pant ◽  
G Ian Gallicano ◽  
Martin Dym
Keyword(s):  
Small Rna ◽  
Small Rnas ◽  
Molecular Mechanisms ◽  
Small Interfering Rnas ◽  
Rna Molecules ◽  
Open Questions ◽  
Complex Process ◽  
Potential Applications ◽  
Pachytene Spermatocytes ◽  
Mitotic Proliferation

Small RNA molecules (small RNAs), including small interfering RNAs (siRNAs), microRNAs (miRNAs), and piwi-interacting RNAs (piRNAs), have recently emerged as important regulators of gene expression at the post-transcriptional or translation level. Significant progress has recently been made utilizing small RNAs in elucidating the molecular mechanisms regulating spermatogenesis. Spermatogenesis is a complex process that involves the division and eventual differentiation of spermatogonial stem cells into mature spermatozoa. The process of spermatogenesis is composed of several phases: mitotic proliferation of spermatogonia to produce spermatocytes; two meiotic divisions of spermatocytes to generate haploid round spermatids; and spermiogenesis, the final phase that involves the maturation of early-round spermatids into elongated mature spermatids. A number of miRNAs are expressed abundantly in male germ cells throughout spermatogenesis, while piRNAs are only present in pachytene spermatocytes and round spermatids. In this review, we first address the synthesis, mechanisms of action, and functions of siRNA, miRNA, and piRNA, and then we focus on the recent advancements in defining the small RNAs in the regulation of spermatogenesis. Concerns pertaining to the use of siRNAs in exploring spermatogenesis mechanisms and open questions in miRNAs and piRNAs in this field are highlighted. The potential applications of small RNAs to male contraception and treatment for male infertility and testicular cancer are also discussed.

scholarly journals hTFtarget: a comprehensive database for regulations of human transcription factors and their targets

2019 ◽  
Author(s):  
Qiong Zhang
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Dna Sequences ◽  
Chromatin Immunoprecipitation ◽  
Target Genes ◽  
Gene Expression Regulation ◽  
Epigenetic Modification ◽  
Wide Range ◽  
Chromatin Immunoprecipitation Sequencing ◽  
User Friendly

Transcription factors (TFs) as key regulators play crucial roles in biological processes. The identification of TF-target regulatory relationships is a key step for revealing functions of TFs and their regulations on gene expression. The accumulated data of Chromatin immunoprecipitation sequencing (ChIP-Seq) provides great opportunities to discover the TF-target regulations across different conditions. In this study, we constructed a database named hTFtarget, which integrated huge human TF target resources (7,190 ChIP-Seq samples of 659 TFs and high confident TF binding sites of 699 TFs) and epigenetic modification information to predict accurate TF-target regulations. hTFtarget offers the following functions for users to explore TF-target regulations: 1) Browse or search general targets of a query TF across datasets; 2) Browse TF-target regulations for a query TF in a specific dataset or tissue; 3) Search potential TFs for a given target gene or ncRNA; 4) Investigate co-association between TFs in cell lines; 5) Explore potential co-regulations for given target genes or TFs; 6) Predict candidate TFBSs on given DNA sequences; 7) View ChIP-Seq peaks for different TFs and conditions in genome browser. hTFtarget provides a comprehensive, reliable and user-friendly resource for exploring human TF-target regulations, which will be very useful for a wide range of users in the TF and gene expression regulation community. hTFtarget is available at http://bioinfo.life.hust.edu.cn/hTFtarget.

scholarly journals Extracting Small RNAs from Human Biological Fluids for Subsequent Next-Generation Sequencing

2019 ◽  
Vol 9 (1) ◽  
pp. 80-86
Author(s):  
O. A. Beylerli ◽  
A. T Beylerli ◽  
I. F. Garaev
Keyword(s):  
Next Generation Sequencing ◽  
Small Rnas ◽  
Biological Fluids ◽  
Rna Extraction ◽  
Small Sample ◽  
Next Generation ◽  
Illumina Platform ◽  
Small Noncoding Rnas ◽  
Organic Extraction ◽  
Generation Sequencing

A number of questions arise when choosing methods for experiments related to next-generation sequencing. On the one hand, while working with RNA extraction, added reagents and their residues can often inhibit sensitive chemicals with which the sequential synthesis is carried out for the sequencing. On the other hand, processing the same data using different software for the analysis can also impact on the sequencing results. This paper will present the step by step procedure for the preparation of samples taken from human biological fluids for subsequent sequencing of small RNAs, small noncoding RNAs in particular. Regarding the methods of extraction or isolation of RNAs, we found that low RNA yield can be improved significantly by following the isolation method for total RNA and its fractions included in Ambion’s MirVana PARIS kit, but only if using a special approach and modifying the organic extraction step. Compared to others, the methods supplied with commercially available kits at the time of researching this paper require only one organic extraction. This simple but, as it turned out, very useful modification makes it possible to access previously unavailable material. Potential advantages of this modification include a more complete profiling of small non-coding RNAs and a broader access to small sample volumes, as a rule, access to human biological fluids which can be prepared for RNA sequencing on the Illumina platform.

scholarly journals Using pan RNA-seq analysis to reveal the ubiquitous existence of 5’ end and 3’ end small RNAs

2018 ◽  
Author(s):  
Xiaofeng Xu ◽  
Haishuo Ji ◽  
Zhi Cheng ◽  
Xiufeng Jin ◽  
Xue Yao ◽  
...  
Keyword(s):  
Gene Expression ◽  
Steady State ◽  
Small Rnas ◽  
Gene Expression Regulation ◽  
Regulation Of Gene Expression ◽  
Cost Effective ◽  
Rna Degradation ◽  
Point Of View ◽  
Rna Seq ◽  
Dsrna Cleavage

AbstractIn this study, we used pan RNA-seq analysis to reveal the ubiquitous existence of 5’ end and 3’ end small RNAs. 5’ and 3’ sRNAs alone can be used to annotate mitochondrial with 1-bp resolution and nuclear non-coding genes and identify new steady-state RNAs, which are usually from functional genes. Using 5’, 3’ and intronic sRNAs, we revealed that the enzymatic dsRNA cleavage and RNAi could involve in the RNA degradation and gene expression regulation of U1 snRNA in human. The further study of 5’, 3’ and intronic sRNAs help rediscover double-stranded RNA (dsRNA) cleavage, RNA interference (RNAi) and the regulation of gene expression, which challenges the classical theories. In this study, we provided a simple and cost effective way for the annotation of mitochondrial and nuclear non-coding genes and the identification of new steady-state RNAs, particularly long non-coding RNAs (lncRNAs). We also provided a different point of view for cancer and virus, based on the new discoveries of dsRNA cleavage, RNAi and the regulation of gene expression.

scholarly journals Whole human genome 5'-mC methylation analysis using long read nanopore sequencing

2021 ◽  
Author(s):  
Catarina Silva ◽  
Miguel Machado ◽  
José Ferrão ◽  
Sebastião Rodrigues ◽  
Luís Vieira
Keyword(s):  
Human Genome ◽  
Cpg Island ◽  
Epigenetic Modification ◽  
Methylation Status ◽  
Enzyme Analysis ◽  
Restriction Enzyme Analysis ◽  
Attractive Alternative ◽  
Nanopore Sequencing ◽  
Coverage Depth ◽  
Genomic Regions

DNA methylation is a type of epigenetic modification that affects gene expression regulation and is associated with several human diseases. Microarray and short read sequencing technologies are often used to study 5'-methylcytosine (5'-mC) modification of CpG dinucleotides in the human genome. Although both technologies produce trustable results, the evaluation of the methylation status of CpG sites suffers from the potential side effects of DNA modification by bisulfite and the ambiguity of mapping short reads in repetitive and highly homologous genomic regions, respectively. Nanopore sequencing is an attractive alternative for the study of 5'-mC since the long reads produced by this technology allow to resolve those genomic regions more easily. Moreover, it allows direct sequencing of native DNA molecules using a fast library preparation procedure. In this work we show that 10X coverage depth nanopore sequencing, using DNA from a human cell line, produces 5'-mC methylation frequencies consistent with those obtained by methylation microarray and digital restriction enzyme analysis of methylation. In particular, the correlation of methylation values ranged from 0.73 to 0.90 using an average genome sequencing coverage depth <2X or a minimum read support of 17X for each CpG site, respectively. We also showed that a minimum of 5 reads per CpG yields strong correlations (>0.89) between sequencing runs and an almost uniform variation in methylation frequencies of CpGs across the entire value range. Furthermore, nanopore sequencing was able to correctly display methylation frequency patterns according to genomic annotations, including a majority of unmethylated and methylated sites in the CpG islands and inter-CpG island regions, respectively. These results demonstrate that low coverage depth nanopore sequencing is a fast, reliable and unbiased approach to the study of 5'-mC in the human genome.

scholarly journals Disentangling sRNA-Seq data to study RNA communication between species

2019 ◽  
Author(s):  
JR Bermúdez-Barrientos ◽  
O Ramírez-Sánchez ◽  
FWN Chow ◽  
AH Buck ◽  
C Abreu-Goodger
Keyword(s):  
Small Rnas ◽  
Animal Species ◽  
De Novo ◽  
Extracellular Vesicle ◽  
Host Cells ◽  
Symbiotic System ◽  
Defense Strategies ◽  
Bioinformatic Tools ◽  
Genomic Regions ◽  
Diverse Plant

ABSTRACTMany organisms exchange small RNAs during their interactions, and these RNAs can target or bolster defense strategies in host-pathogen systems. Current sRNA-Seq technology can determine the small RNAs present in any symbiotic system, but there are very few bioinformatic tools available to interpret the results. We show that one of the biggest challenges comes from sequences that map equally well to the genomes of both interacting organisms. This arises due to the small size of the sRNA compared to large genomes, and because many of the produced sRNAs come from genomic regions that encode highly conserved miRNAs, rRNAs or tRNAs. Here we present strategies to disentangle sRNA-Seq data from samples of communicating organisms, developed using diverse plant and animal species that are known to exchange RNA with their parasites. We show that sequence assembly, both de novo and genome-guided, can be used for sRNA-Seq data, greatly reducing the ambiguity of mapping reads. Even confidently mapped sequences can be misleading, so we further demonstrate the use of differential expression strategies to determine the true parasitic sRNAs within host cells. Finally, we validate our methods on new experiments designed to probe the nature of the extracellular vesicle sRNAs from the parasitic nematode H. bakeri that get into mouse epithelial cells.

scholarly journals Dynamic regulation of chromatin topology and transcription by inverted repeat-derived small RNAs in sunflower

2019 ◽  
Vol 116 (35) ◽  
pp. 17578-17583 ◽  
Author(s):  
Delfina Gagliardi ◽  
Damian A. Cambiagno ◽  
Agustin L. Arce ◽  
Ariel H. Tomassi ◽  
Jorge I. Giacomelli ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Inverted Repeat ◽  
Small Rnas ◽  
Rna Silencing ◽  
De Novo ◽  
Epigenetic Modification ◽  
Regulatory Elements ◽  
Dynamic Regulation ◽  
Transposon Activity ◽  
De Novo Methylation

Transposable elements (TEs) are extremely abundant in complex plant genomes. siRNAs of 24 nucleotides in length control transposon activity in a process that involves de novo methylation of targeted loci. Usually, these epigenetic modifications trigger nucleosome condensation and a permanent silencing of the affected loci. Here, we show that a TE-derived inverted repeat (IR) element, inserted near the sunflower HaWRKY6 locus, dynamically regulates the expression of the gene by altering chromatin topology. The transcripts of this IR element are processed into 24-nt siRNAs, triggering DNA methylation on its locus. These epigenetic marks stabilize the formation of tissue-specific loops in the chromatin. In leaves, an intragenic loop is formed, blocking HaWRKY6 transcription. While in cotyledons (Cots), formation of an alternative loop, encompassing the whole HaWRKY6 gene, enhances transcription of the gene. The formation of this loop changes the promoter directionality, reducing IR transcription, and ultimately releasing the loop. Our results provide evidence that TEs can act as active and dynamic regulatory elements within coding loci in a mechanism that combines RNA silencing, epigenetic modification, and chromatin remodeling machineries.

The long hand of the small RNAs reaches into several levels of gene regulation

2004 ◽  
Vol 82 (4) ◽  
pp. 472-481 ◽  
Author(s):  
Tony Nolan ◽  
Carlo Cogoni
Keyword(s):  
Gene Silencing ◽  
Small Rnas ◽  
Developmental Regulation ◽  
Transcriptional Gene Silencing ◽  
Rna Molecules ◽  
New Class ◽  
Post Transcriptional Gene Silencing ◽  
Wide Range ◽  
Cellular Defence ◽  
Genomic Organisation

Small RNA molecules such as siRNAs and miRNAs represent a new class of molecules that have been implicated in a wide range of diverse gene silencing phenomena. It is now becoming clear that these two similar molecules share several common features in both their biogenesis and their mechanism of action. Thus, the siRNA and miRNA pathways may have evolved from a common ancestral mechanism that has diverged to play important roles in developmental regulation, genomic organisation, and cellular defence against foreign nucleic acids.Key words: miRNA, siRNA, post-transcriptional gene silencing, RNAi, heterochromatin.

5′-YRNA fragments derived by processing of transcripts from specific YRNA genes and pseudogenes are abundant in human serum and plasma

2013 ◽  
Vol 45 (21) ◽  
pp. 990-998 ◽  
Author(s):  
Joseph M. Dhahbi ◽  
Stephen R. Spindler ◽  
Hani Atamna ◽  
Dario Boffelli ◽  
Patricia Mote ◽  
...  
Keyword(s):  
Human Serum ◽  
Small Rnas ◽  
Healthy Adult ◽  
Connective Tissue Diseases ◽  
Mouse Serum ◽  
Internal Loop ◽  
Small Noncoding Rnas ◽  
Signaling Function ◽  
Adult Humans ◽  
Multiple Species

Small noncoding RNAs carry out a variety of functions in eukaryotic cells, and in multiple species they can travel between cells, thus serving as signaling molecules. In mammals multiple small RNAs have been found to circulate in the blood, although in most cases the targets of these RNAs, and even their functions, are not well understood. YRNAs are small (84–112 nt) RNAs with poorly characterized functions, best known because they make up part of the Ro ribonucleoprotein autoantigens in connective tissue diseases. In surveying small RNAs present in the serum of healthy adult humans, we have found YRNA fragments of lengths 27 nt and 30–33 nt, derived from the 5′-ends of specific YRNAs and generated by cleavage within a predicted internal loop. Many of the YRNAs from which these fragments are derived were previously annotated only as pseudogenes, or predicted informatically. These 5′-YRNA fragments make up a large proportion of all small RNAs (including miRNAs) present in human serum. They are also present in plasma, are not present in exosomes or microvesicles, and circulate as part of a complex with a mass between 100 and 300 kDa. Mouse serum contains far fewer 5′-YRNA fragments, possibly reflecting the much greater copy number of YRNA genes and pseudogenes in humans. The function of the 5′-YRNA fragments is at present unknown, but the processing and secretion of specific YRNAs to produce 5′-end fragments that circulate in stable complexes are consistent with a signaling function.

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