scholarly journals Engineering rules that minimize germline silencing of transgenes in simple extrachromosomal arrays in C. elegans

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammed D. Aljohani ◽  
Sonia El Mouridi ◽  
Monika Priyadarshini ◽  
Amhed M. Vargas-Velazquez ◽  
Christian Frøkjær-Jensen
Keyword(s):  
Fluorescent Proteins ◽  
Single Copy ◽  
Regulatory Elements ◽  
Transgene Silencing ◽  
Small Interfering Rnas ◽  
Web Based ◽  
C Elegans ◽  
Genomic Location ◽  
Germline Expression ◽  
Extensive Collection

AbstractTransgenes are prone to progressive silencing due to their structure, copy number, and genomic location. In C. elegans, repressive mechanisms are particularly strong in the germline with almost fully penetrant transgene silencing in simple extrachromosomal arrays and frequent silencing of single-copy transgene insertions. A class of non-coding DNA, Periodic An/Tn Clusters (PATCs) can prevent transgene-silencing in repressive chromatin or from small interfering RNAs (piRNAs). Here, we describe design rules (codon-optimization, intron and PATC inclusion, elevated temperature (25 °C), and vector backbone removal) for efficient germline expression from arrays in wildtype animals. We generate web-based tools to analyze PATCs and reagents for the convenient assembly of PATC-rich transgenes. An extensive collection of silencing resistant fluorescent proteins (e.g., gfp, mCherry, and tagBFP) can be used for dissecting germline regulatory elements and a set of enhanced enzymes (Mos1 transposase, Cas9, Cre, and Flp recombinases) enable efficient genetic engineering in C. elegans.

scholarly journals Mating can initiate stable RNA silencing that overcomes epigenetic recovery

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sindhuja Devanapally ◽  
Pravrutha Raman ◽  
Mary Chey ◽  
Samual Allgood ◽  
Farida Ettefa ◽  
...  
Keyword(s):  
Small Rna ◽  
Rna Silencing ◽  
Single Copy ◽  
Regulatory Sequences ◽  
Epigenetic Changes ◽  
Double Stranded Rna ◽  
Transient Change ◽  
C Elegans ◽  
Homologous Sequences ◽  
Germline Expression

AbstractStable epigenetic changes appear uncommon, suggesting that changes typically dissipate or are repaired. Changes that stably alter gene expression across generations presumably require particular conditions that are currently unknown. Here we report that a minimal combination of cis-regulatory sequences can support permanent RNA silencing of a single-copy transgene and its derivatives in C. elegans simply upon mating. Mating disrupts competing RNA-based mechanisms to initiate silencing that can last for >300 generations. This stable silencing requires components of the small RNA pathway and can silence homologous sequences in trans. While animals do not recover from mating-induced silencing, they often recover from and become resistant to trans silencing. Recovery is also observed in most cases when double-stranded RNA is used to silence the same coding sequence in different regulatory contexts that drive germline expression. Therefore, we propose that regulatory features can evolve to oppose permanent and potentially maladaptive responses to transient change.

scholarly journals SapTrap assembly of C. elegans MosSCI transgene vectors

2019 ◽  
Author(s):  
Xintao Fan ◽  
Sasha De Henau ◽  
Julia Feinstein ◽  
Stephanie I. Miller ◽  
Bingjie Han ◽  
...  
Keyword(s):  
Single Copy ◽  
Regulatory Elements ◽  
Modular Assembly ◽  
C Elegans ◽  
Control Gene Expression ◽  
One Step ◽  
Fluorescent Tags ◽  
The One ◽  
Targeting Vector ◽  
Single Reaction

AbstractThe Mos1-mediated Single-Copy Insertion (MosSCI) method is widely used to establish stable Caenorhabditis elegans transgenic strains. Cloning MosSCI targeting plasmids can be cumbersome because it requires assembling multiple genetic elements including a promoter, a 3’UTR and gene fragments. Recently, Schwartz and Jorgensen developed the SapTrap method for the one-step assembly of plasmids containing components of the CRISPR/Cas9 system for C. elegans (Schwartz and Jorgensen 2016 Genetics, 202:1277-1288). Here, we report on the adaptation of the SapTrap method for the efficient and modular assembly of a promoter, 3’UTR and either 2 or 3 gene fragments in a MosSCI targeting vector in a single reaction. We generated a toolkit that includes several fluorescent tags, components of the ePDZ/LOV optogenetic system and regulatory elements that control gene expression in the C. elegans germline. As a proof of principle, we generated a collection of strains that fluorescently label the endoplasmic reticulum and mitochondria in the hermaphrodite germline and that enable the light-stimulated recruitment of mitochondria to centrosomes in the one-cell worm embryo. The method described here offers a flexible and efficient method for assembly of custom MosSCI targeting vectors.

scholarly journals SapTrap Assembly of Caenorhabditis elegans MosSCI Transgene Vectors

2019 ◽  
Vol 10 (2) ◽  
pp. 635-644 ◽  
Author(s):  
Xintao Fan ◽  
Sasha De Henau ◽  
Julia Feinstein ◽  
Stephanie I. Miller ◽  
Bingjie Han ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Single Copy ◽  
Regulatory Elements ◽  
Modular Assembly ◽  
C Elegans ◽  
One Step ◽  
Fluorescent Tags ◽  
The One ◽  
Targeting Vector ◽  
Single Reaction

The Mos1-mediated Single-Copy Insertion (MosSCI) method is widely used to establish stable Caenorhabditis elegans transgenic strains. Cloning MosSCI targeting plasmids can be cumbersome because it requires assembling multiple genetic elements including a promoter, a 3′UTR and gene fragments. Recently, Schwartz and Jorgensen developed the SapTrap method for the one-step assembly of plasmids containing components of the CRISPR/Cas9 system for C. elegans. Here, we report on the adaptation of the SapTrap method for the efficient and modular assembly of a promoter, 3′UTR and either 2 or 3 gene fragments in a MosSCI targeting vector in a single reaction. We generated a toolkit that includes several fluorescent tags, components of the ePDZ/LOV optogenetic system and regulatory elements that control gene expression in the C. elegans germline. As a proof of principle, we generated a collection of strains that fluorescently label the endoplasmic reticulum and mitochondria in the hermaphrodite germline and that enable the light-stimulated recruitment of mitochondria to centrosomes in the one-cell worm embryo. The method described here offers a flexible and efficient method for assembly of custom MosSCI targeting vectors.

scholarly journals Split-wrmScarlet and split-sfGFP: Tools for faster, easier fluorescent l abeling of endogenous proteins in Caenorhabditis elegans

Genetics ◽  
2021 ◽  
Author(s):  
Jérôme Goudeau ◽  
Catherine S Sharp ◽  
Jonathan Paw ◽  
Laura Savy ◽  
Manuel D Leonetti ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Fluorescent Labeling ◽  
Large Fragment ◽  
C Elegans ◽  
High Affinity ◽  
Red Fluorescent Proteins ◽  
Invaluable Tool ◽  
Endogenous Proteins ◽  
Fluorescent Tags

Abstract We create and share a new red fluorophore, along with a set of strains, reagents and protocols, to make it faster and easier to label endogenous C. elegans proteins with fluorescent tags. CRISPR-mediated fluorescent labeling of C. elegans proteins is an invaluable tool, but it is much more difficult to insert fluorophore-size DNA segments than it is to make small gene edits. In principle, high-affinity asymmetrically split fluorescent proteins solve this problem in C. elegans: the small fragment can quickly and easily be fused to almost any protein of interest, and can be detected wherever the large fragment is expressed and complemented. However, there is currently only one available strain stably expressing the large fragment of a split fluorescent protein, restricting this solution to a single tissue (the germline) in the highly autofluorescent green channel. No available C. elegans lines express unbound large fragments of split red fluorescent proteins, and even state-of-the-art split red fluorescent proteins are dim compared to the canonical split-sfGFP protein. In this study, we engineer a bright, high-affinity new split red fluorophore, split-wrmScarlet. We generate transgenic C. elegans lines to allow easy single-color labeling in muscle or germline cells and dual-color labeling in somatic cells. We also describe a novel expression strategy for the germline, where traditional expression strategies struggle. We validate these strains by targeting split-wrmScarlet to several genes whose products label distinct organelles, and we provide a protocol for easy, cloning-free CRISPR/Cas9 editing. As the collection of split-FP strains for labeling in different tissues or organelles expands, we will post updates at doi.org/10.5281/zenodo.3993663

scholarly journals Exploring functionally annotated transcriptional consensus regulatory elements with CONREL

Database ◽  
2020 ◽  
Vol 2020 ◽  
Author(s):  
Davide Dalfovo ◽  
Samuel Valentini ◽  
Alessandro Romanel
Keyword(s):  
Cell Lines ◽  
Web Application ◽  
Regulatory Networks ◽  
Regulatory Elements ◽  
Levels Of Abstraction ◽  
Binding Motifs ◽  
Extensive Collection ◽  
Transcription Factor Binding Motifs ◽  
Gene Regulatory ◽  
Genomic Regions

Abstract Understanding the interaction between human genome regulatory elements and transcription factors is fundamental to elucidate the structure of gene regulatory networks. Here we present CONREL, a web application that allows for the exploration of functionally annotated transcriptional ‘consensus’ regulatory elements at different levels of abstraction. CONREL provides an extensive collection of consensus promoters, enhancers and active enhancers for 198 cell-lines across 38 tissue types, which are also combined to provide global consensuses. In addition, 1000 Genomes Project genotype data and the ‘total binding affinity’ of thousands of transcription factor binding motifs at genomic regulatory elements is fully combined and exploited to characterize and annotate functional properties of our collection. Comparison with other available resources highlights the strengths and advantages of CONREL. CONREL can be used to explore genomic loci, specific genes or genomic regions of interest across different cell lines and tissue types. The resource is freely available at https://bcglab.cibio.unitn.it/conrel.

scholarly journals Notch-dependent DNA cis-regulatory elements and their dose-dependent control of C. elegans stem cell self-renewal

2021 ◽  
Author(s):  
Tina R. Lynch ◽  
Mingyu Xue ◽  
Cazza W. Czerniak ◽  
ChangHwan Lee ◽  
Judith Kimble
Keyword(s):  
Stem Cell ◽  
Regulatory Elements ◽  
Single Element ◽  
Developmental Context ◽  
C Elegans ◽  
Stem Cell Maintenance ◽  
Nascent Transcripts ◽  
Functional Analyses ◽  
Dose Dependent

A long-standing biological question is how DNA cis-regulatory elements shape transcriptional patterns during metazoan development. The use of reporter constructs, cell culture and computational modeling has made enormous contributions to understanding this fundamental question, but analysis of regulatory elements in their natural developmental context is an essential but rarely used complement. Here, we edited Notch-dependent cis-regulatory elements in the endogenous C. elegans sygl-1 gene, which encodes a key stem cell regulator. We then analyzed the in vivo consequences of those mutations – on both gene expression (nascent transcripts, mRNA, protein) and stem cell maintenance. Mutation of a single element in a three-element homotypic cluster reduced expression as well as stem cell pool size by about half, while mutation of two elements essentially abolished them. We find that LBS number and LBS neighborhood are both important to activity: elements on separate chromosomes function additively, while elements in the same cluster act synergistically. Our approach of precise CRISPR/Cas9 gene editing coupled with quantitation of both molecular and biological readouts establishes a powerful model for in vivo functional analyses of DNA cis-regulatory elements.

scholarly journals Chromatin accessibility is dynamically regulated across C. elegans development and ageing

2018 ◽  
Author(s):  
Jürgen Jänes ◽  
Yan Dong ◽  
Michael Schoof ◽  
Jacques Serizay ◽  
Alex Appert ◽  
...  
Keyword(s):  
Regulatory Mechanism ◽  
Regulatory Elements ◽  
Chromatin Accessibility ◽  
Protein Coding ◽  
C Elegans ◽  
Transcription Profiles ◽  
Physiological Processes ◽  
Global Identification ◽  
Identification And Characterization

AbstractAn essential step for understanding the transcriptional circuits that control development and physiology is the global identification and characterization of regulatory elements. Here we present the first map of regulatory elements across the development and ageing of an animal, identifying 42,245 elements accessible in at least one C. elegans stage. Based on nuclear transcription profiles, we define 15,714 protein-coding promoters and 19,231 putative enhancers, and find that both types of element can drive orientation-independent transcription. Additionally, hundreds of promoters produce transcripts antisense to protein coding genes, suggesting involvement in a widespread regulatory mechanism. We find that the accessibility of most elements is regulated during development and/or ageing and that patterns of accessibility change are linked to specific developmental or physiological processes. The map and characterization of regulatory elements across C. elegans life provides a platform for understanding how transcription controls development and ageing.

scholarly journals Alzheimer’s disease-relevant tau modifications selectively impact neurodegeneration and mitophagy in a novel C. elegans single-copy transgenic model

2020 ◽  
Author(s):  
Sanjib Guha ◽  
Sarah Fischer ◽  
Gail VW Johnson ◽  
Keith Nehrke
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Genetic Model ◽  
Neurodegenerative Disorder ◽  
Model Organism ◽  
Single Copy ◽  
Mitochondrial Stress ◽  
C Elegans ◽  
Touch Receptor Neurons ◽  
New Perspective

ABSTRACTBackgroundA defining pathological hallmark of the progressive neurodegenerative disorder Alzheimer’s disease (AD) is the accumulation of misfolded tau with abnormal post-translational modifications (PTMs). These include phosphorylation at Threonine 231 (T231) and acetylation at Lysine 274 (K274) and at Lysine 281 (K281). Although tau is recognized to play a central role in pathogenesis of AD, the precise mechanisms by which these abnormal PTMs contribute to the neural toxicity of tau is unclear.MethodsHuman 0N4R tau (wild type) was expressed in touch receptor neurons of the genetic model organism C. elegans through single-copy gene insertion. Defined mutations were then introduced into the single-copy tau transgene through CRISPR-Cas9 genome editing. These mutations included T231E and T231A, to mimic phosphorylation and phospho-ablation of a commonly observed pathological epitope, respectively, and K274/281Q, to mimic disease-associated lysine acetylation. Stereotypical touch response assays were used to assess behavioral defects in the transgenic strains as a function of age, and genetically-encoded fluorescent biosensors were used to measure the morphological dynamics and turnover of touch neuron mitochondria.ResultsUnlike existing tau overexpression models, C. elegans single-copy expression of tau did not elicit overt pathological phenotypes at baseline. However, strains expressing disease associated PTM-mimetics (T231E and K274/281Q) exhibited reduced touch sensation and morphological abnormalities that increased with age. In addition, the PTM-mimetic mutants lacked the ability to engage mitophagy in response to mitochondrial stress.ConclusionsLimiting the expression of tau results in a genetic model where pathological modifications and age result in evolving phenotypes, which may more closely resemble the normal progression of AD. The finding that disease-associated PTMs suppress compensatory responses to mitochondrial stress provides a new perspective into the pathogenic mechanisms underlying AD.

scholarly journals Small RNAs in parasitic nematodes – forms and functions

Parasitology ◽  
2019 ◽  
Vol 147 (8) ◽  
pp. 855-864
Author(s):  
Collette Britton ◽  
Roz Laing ◽  
Eileen Devaney
Keyword(s):  
Gene Expression ◽  
Small Rna ◽  
Small Rnas ◽  
Target Genes ◽  
Parasitic Nematodes ◽  
Small Rna Sequencing ◽  
Small Interfering Rnas ◽  
Rna Sequences ◽  
C Elegans

AbstractSmall RNAs are important regulators of gene expression. They were first identified in Caenorhabditis elegans, but it is now apparent that the main small RNA silencing pathways are functionally conserved across diverse organisms. Availability of genome data for an increasing number of parasitic nematodes has enabled bioinformatic identification of small RNA sequences. Expression of these in different lifecycle stages is revealed by small RNA sequencing and microarray analysis. In this review we describe what is known of the three main small RNA classes in parasitic nematodes – microRNAs (miRNAs), Piwi-interacting RNAs (piRNAs) and small interfering RNAs (siRNAs) – and their proposed functions. miRNAs regulate development in C. elegans and the temporal expression of parasitic nematode miRNAs suggest modulation of target gene levels as parasites develop within the host. miRNAs are also present in extracellular vesicles released by nematodes in vitro, and in plasma from infected hosts, suggesting potential regulation of host gene expression. Roles of piRNAs and siRNAs in suppressing target genes, including transposable elements, are also reviewed. Recent successes in RNAi-mediated gene silencing, and application of small RNA inhibitors and mimics will continue to advance understanding of small RNA functions within the parasite and at the host–parasite interface.

Sign in / Sign up

Export Citation Format

Share Document