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Directed Evolution of an Adenine Base Editor with Increased Activity and Context Compatibility [RNA-seq data]

ABSTRACT: It is known that current the-art-of-the-state TadA8 and TadA8e which evolved from E. coli TadA. They inherited the 'YA' context from tRNA deaminase. We started with wildtype E. coli TadA and designed an evolution campaign to force TadA variants to deaminate “GA” with fast kinetics. Three rounds of de novo directed evolution followed by DNA shuffling led to TadA8r, a TadA variant of superior “RA” deamination activity. TadA8r acts on a broadened editing window when fused to Streptococcus pyogenes Cas9 (SpCas9) and delivers robust editing at PAM distal positions. While highly active at on-target sites, ABE8r shows off-target DNA and RNA editing much lower than ABE8e. The off-target effects of ABE8r can be further mitigated by introducing a V106W substitution23, a R153 deletion22, or by mRNA delivery. Lastly, we demonstrate ABE8r-mediated correction of G1961E in ABCA4, the most prevalent mutation driving Stargardt disease (STGD1), in a “GA” context. ABE8r, with its superior activity and broadened context compatibility, complements and expands the current ABE family.

ORGANISM(S): Homo sapiens

PROVIDER: GSE220469 | GEO | 2023/09/14

REPOSITORIES: GEO

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Directed Evolution of an Adenine Base Editor withIncreased Activity and Context Compatibility [sgRNA-target library]

Project description:Adenine base editors (ABEs) are precise gene-editing agents that convert A:T pairs into G:C through a deoxyinosine intermediate. ABEs function most effectively when the target A is in a TA context. Deficient ABE processing of RA (R = A or G) is most evident when the target A is outside the comfortable editing window or when delivery is suboptimal. In the current study, we report directed evolution of TadA8r, a new variant of the Escherichia coli tRNA-specific adenosine deaminase (TadA) with ultra-fast deoxyadenosine deamination and no context bias.

2023-09-14 | GSE242012 | GEO

Escherichia coli strain:TadA

Project description:Abe8e TadA directed evolution campaign sequencing

| PRJNA625103 | ENA

Nascent-seq indicates widespread cotranscriptional RNA editing in Drosophila

Project description:The RNA editing enzyme ADAR chemically modifies adenosine (A) to inosine (I), which is interpreted by the ribosome as a guanosine. Here we assess cotranscriptional A-to-I editing in Drosophila, by isolating nascent RNA from adult fly heads and subjecting samples to high-throughput sequencing. There are a large number of edited sites within nascent exons. Nascent RNA from an ADAR null mutant strain was also sequenced, indicating that almost all A-to-I events require ADAR. Moreover, mRNA editing levels correlate with editing levels within the cognate nascent RNA sequence, indicating that the extent of editing is set cotranscriptionally. Surprisingly, the nascent data also identify an excess of intronic over exonic editing sites. These intronic sites occur preferentially within introns that are poorly spliced cotranscriptionally, suggesting a link between editing and splicing. We conclude that ADAR-mediated editing is more widespread than previously indicated and largely occurs cotranscriptionally. GSM914095: Fly genomic DNA sequencing. Sequenced on the Illumina GA II. GSM914102-GSM914113: Fly head nascent RNA profiles over 6 time points of a 12hr light:dark cycle in duplicate; sequenced on the Illumina GA II. GSM914114-GSM914119: Fly head nascent RNA profiles of yw, FM7, ADAR0 males in duplicate; sequenced on the HiSeq2000. GSM915213-GSM915214: Fly head mRNA profiles over 2 time points of a 12hr light:dark cycle; sequenced on the Illumina GA II. GSM915215-GSM915220: Fly head mRNA profiles over 6 time points of a 12hr light:dark cycle; paired-end sequenced on the Illumina GA II. GSM915221-GSM91526: Fly head mRNA profiles over 6 time points of a 12hr light:dark cycle; sequenced on the Illumina GA II.

2012-05-31 | E-GEOD-37232 | biostudies-arrayexpress

Project description:Abe8e directed evolution campaign sequencing

| PRJNA625117 | ENA

RNA-sequencing of neonatal monocyte responses to E. coli and S. epidermidis

Project description:Newborns, particularly those born prematurely, are extremely vulnerable to sepsis and this has been attributed to ‘immature’ innate monocyte defences. Predominant pathogens include Escherichia. coli and Staphylococcus. epidermidis but no studies have assessed global transcriptional responses of neonatal monocytes to live sepsis-causing bacteria. Here, we aimed to identify and characterise the common and pathogen-specific, neonatal monocyte transcriptional responses to E. coli and S. epidermidis to better understand early life innate immune responses. RNA-sequencing was performed on purified cord blood monocytes from very preterm (<32 weeks gestational age, GA) and term infants (37-40 weeks GA) following standardised challenge with live S. epidermidis or E. coli.

2018-03-16 | GSE101880 | GEO

FlyORF-TaDa allows rapid generation of new lines for in vivo cell-type specific profiling of protein-DNA interactions in Drosophila melanogaster

Project description:Targeted DamID (TaDa) is an increasingly popular method of generating cell-type specific DNA binding profiles in vivo. Although sensitive and versatile, TaDa requires the generation of new transgenic fly lines for every protein that is profiled, which is both time-consuming and costly. Here, we describe the FlyORF-TaDa system for converting an existing FlyORF library of inducible open reading frames (ORFs) to TaDa lines via a genetic cross, with recombinant progeny easily identifiable by eye colour. Profiling the binding of the H3K36me3-associated chromatin protein MRG15 in larval neural stem cells using both FlyORF-TaDa and conventional TaDa demonstrates that new lines generated using this system provide accurate and highly-reproducible DamID binding profiles. Our data further show that MRG15 binds to a subset of active chromatin domains in vivo. Courtesy of the large coverage of the FlyORF library, the FlyORF-TaDa system enables the easy creation of TaDa lines for 74% of all transcription factors and chromatin modifying proteins within the Drosophila genome.

2021-01-31 | GSE159632 | GEO

Cis- and trans-regulation of alternative splicing by Adenosine Deaminase Acting on the double-stranded RNA (ADAR) proteins

Project description:RNA editing and splicing are the two major processes that dynamically regulate human transcriptome diversity. Despite growing evidence of crosstalk between RNA editing enzymes (mainly ADAR1) and splicing machineries, detailed mechanistic explanations and their biological importance in diseases, such as cancer are still lacking. Herein, we identify approximately a hundred high-confidence splicing events altered by ADAR1 and/or ADAR2, and ADAR1 or ADAR2 protein can regulate cassette exons in both directions. We unravel a binding tendency of ADARs to dsRNAs that involves GA-rich sequences for editing and splicing regulation. ADAR1 edits an intronic splicing silencer, leading to recruitment of SRSF7 and repression of exon inclusion. We also present a mechanism through which ADAR2 binds to dsRNA formed between GA-rich sequences and polypyrimidine (Py)-tract and precludes access of U2AF65 to 3′ splice site. Furthermore, we find these ADARs-regulated splicing changes per se influence tumorigenesis, not merely byproducts of ADARs editing and binding.

2019-12-22 | GSE131658 | GEO

Specific combinatorial mutations in MIR396 genes enlarge the grain size and modulate the plant architecture in rice

Project description:miR396 is a key growth regulator in plants, however, the molecular mechanisms underlying its functions remained to be revealed. Here, through systematically gene-editing, we found that among the MIR396 family genes, MIR396e and -f were the main regulators of rice growth. mir396ef mutations could increase the grain yield through significantly enlarging the grain size. In addition, mir396ef mutations promoted the seedling growth and modulated the plant architecture by promoting the elongations of leaves (including leaf blades and sheaths) and panicles but suppressing the elongation of internodes, especially the uppermost internode. Our research reveals that mir396ef mutations promote the growth and organ elongation by significantly increasing the level of the gibberellin (GA) precursor, mevalonic acid (MVA), which subsequently activates the GA pathway. Our results also indicate that miR396 regulates the internode elongation through a different mechanism (probably through controlling SD37 expression) from the GA pathway. These results reveal two pathways by which miR396 regulates rice growth and provide valuable gene-editing targets to increase rice productivity.

2019-07-24 | GSE113319 | GEO

Profiling of RNA Pol II occupancy in adult Drosophila terminal tracheal cell using TaDa (Targeted DamID) in context of homeostasis or damaged intestine

Project description:Cell-type specific transcriptional profiling is key to understanding cell fate specification, function and adaptation. This is particularly advantageous for studying specific cell types from complex tissues. In this study, we have used ‘TaDa’ (Targeted DamID), a technique that enables profiling of rare cell populations or cells difficult to isolate by conventional methods. Furthermore, TaDa profiling occurs in vivo and isn’t subject to artefacts arising from disruption of the tissues and cell sorting. Here, we profile the genome-wide binding of RNA polymerase II (Pol II) in terminal tracheal cells (TTCs) that are tightly associated with intestinal tissue from adult Drosophila. We compare terminal tracheal transcriptome from control to regenerative intestine in adult fly. Our data reveal new tracheal intrinsic mechanisms that are essential, in this gut-trachea communication, for regulating intestinal stem cell proliferative activity in context of damage. Our study represents the first analysis of terminal tracheal cell transcriptional profiling in context of homeostasis and regenerative adult intestine and provide new insight into the regulatory programs that underlie the complex interactions between gut-neighbourhood.

2020-12-21 | GSE163570 | GEO

Caste-specific RNA editomes in the leaf-cutting ant Acromyrmex echinatior

Project description:Eusocial insects have evolved the capacity to generate adults with distinct morphological, reproductive and behavioural phenotypes from the same genome. Recent studies suggest that RNA editing might enhance the diversity of gene products at the post-transcriptional level, particularly to induce functional changes in the nervous system. Using head samples from the leaf-cutting ant Acromyrmex echinatior, we compare RNA editomes across eusocial castes, identifying ca. 11,000 RNA editing sites in gynes, large workers and small workers. Those editing sites map to 800 genes functionally enriched for neurotransmission, circadian rhythm, temperature response, RNA splicing and carboxylic acid biosynthesis. Most A. echinatior editing sites are species specific, but 8M-bM-^@M-^S23% are conserved across ant subfamilies and likely to have been important for the evolution of eusociality in ants. The level of editing varies for the same site between castes, suggesting that RNA editing might be a general mechanism that shapes caste behaviour in ants. Analysis of genome-wide RNA editing in three different female castes of the the leaf-cutting ant Acromyrmex echinatior.

2014-10-02 | E-GEOD-51576 | biostudies-arrayexpress

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