RNAi-mediated rheostat for dynamic control of AAV-delivered transgenes
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ABSTRACT:
ORGANISM(S): Rattus norvegicus Mus musculus Homo sapiens
PROVIDER: GSE214065 | GEO | 2023/01/31
REPOSITORIES: GEO
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Project description:Hairpin RNA (hpRNA) transgenes, with a perfect inverted-repeat (IR) DNA, have been the most successful RNA interference (RNAi) method in plants. Here we show that hpRNA transgenes were invariably methylated in the IR DNA and the adjacent promoter, causing transcriptional self-silencing and preventing the full potential of RNAi. Nucleotide substitutions in the sense sequence, which disrupts the perfect IR DNA structure, were sufficient to prevent the intrinsic DNA methylation resulting in more uniform and persistent RNAi. Substituting all cytosine (C) with thymine (T) nucleotides, in a G:U hpRNA design, prevented DNA methylation and self-silencing but still allowed for the formation of perfect hpRNA due to G:U wobble base-pairing. The G:U design induces effective RNAi in 90-96% of transgenic lines, compared to 57-65% for the traditional hpRNA design. Furthermore, while a traditional hpRNA transgene showed increasing DNA methylation and self-silencing from cotyledons to true leaves, the G:U transgenes avoided this developmental progression of self-silencing and induced RNAi throughout plant growth. The G:U and traditional hpRNA transgenes generated small interfering RNA (siRNA) with different 5’ phosphorylation, which resembled the endogenous tasiRNA and miRNA, respectively. Furthermore, our results suggest that siRNAs from the two transgene designs function differently to induce target DNA methylation, one (from traditional hpRNA) through the canonical RdDM pathway and the other (G:U hpRNA) a non-canonical pathway. Our study not only revealed a methylation-resistant RNAi transgene design but also provided new mechanistic insights into small RNA biogenesis and function in plants
2022-03-31 | GSE178565 | GEO
Project description:The RNA interference (RNAi) pathway has evolved numerous functionalities in eukaryotes, with many on display in Kingdom Fungi. RNAi can regulate gene expression, facilitate drug resistance, or even be altogether lost to improve growth potential in some fungal pathogens. In the WHO fungal priority pathogen, Aspergillus fumigatus, the RNAi system is known to be intact and functional. To extend our limited understanding of A. fumigatus RNAi, we first investigated the genetic variation in RNAi-associated genes in a large collection of environmental and clinical genomes, where we found that RNAi is evolutionarily conserved even in clinical strains. Using endogenously expressed inverted-repeat transgenes complementary to both a conditionally essential gene and a nonessential gene, we determined that a subset of the RNAi componentry is active in inverted-repeat transgene silencing in conidia and mycelium. A multi-condition mRNA-seq analysis linked the A. fumigatus dicer-like enzymes and RNA-dependent RNA polymerases to regulation of conidial ribosome biogenesis genes; however, surprisingly few endogenous small RNAs were identified in conidia that could explain this broad change. Although RNAi was not clearly linked to growth or stress response defects in the RNAi knockouts, serial passaging of RNAi knockout strains for six generations resulted in lineages with diminished spore production over time, indicating that loss of RNAi can exert a fitness cost on the fungus. Cumulatively, A. fumigatus RNAi appears to play an active role in defense against double-stranded RNA species alongside a previously unappreciated housekeeping function in regulation of conidial ribosomal biogenesis genes.
2023-02-17 | PXD039739 | Pride
Project description:Despite rapid progress in the development of new therapies based on adeno-associated viral vectors (AAVs) in recent years, successful transduction of the human heart remains challenging. So far, the mechanisms that impede AAV transduction, especially in humans are poorly understood, hampering the introduction of new, effective gene therapy strategies. Therefore, the aim of this study was to identify and overcome the main cellular barriers to successful transduction in the heart, using iPSC-derived cardiomyocytes (iPSC-CMs), cardiac fibroblasts (iPSC-CFs), and primary endothelial cells (HAECs) to model vector-host interactions. Through phosphoproteome analysis of AAV9-transduced iPSC-CFs we established that casein kinase 2 (CK2) signalling is one of the most significantly affected pathways upon AAV exposure. Importantly, transient inhibition of CK2 activity with silmitasertib substantially enhanced the transduction rate of AAV2, AAV6 and AAV9 in all tested cell types (iPSC-CMs, iPSC-CFs and HAECs), demonstrating the versatility of this approach. CK2 inhibition improved the trafficking of AAVs through the cytoplasm and impaired DNA-damage response through destabilisation of Mre11, sensor of dsDNA breaks, that directly binds the ITRs of the vector genome. Silmitasertib treatment also allowed for improvement of transgene expression in already transduced iPSC-CFs, which retain AAV genomes in a functional, but probably silent form. Furthermore, our analysis revealed that AAV transduction may interfere with RNA processing pathways, identifying matrin-3 as a necessary factor for efficient transgene delivery. In summary, presented study provides new insights into the current understanding of the host-AAV vector interaction, identifying CK2 activity as a key barrier to efficient transduction and transgene expression, therefore offering a promising strategy to improve the outcome of AAV-based therapies in the future.
2024-03-28 | PXD040035 | Pride
Project description:The study of microglia biology and the development of microglia-based gene therapies are in urgent need of efficient and safe vehicles for microglia transgene delivery. To address this, we developed adeno-associated virus (AAV) variants that mediate efficient in vitro and in vivo microglia transduction via directed evolution of the AAV capsid protein. To assess the effect of AAV transduction on microglia, we carried out bulk RNAseq in primary microglia and found that microglia transduced by AAV remain close to homeostatic state. Furthermore, single-cell RNA sequencing showed that the AAV-MG variants mediate safe in vivo transgene delivery without inducing microglia immune activation. These AAV variants should facilitate the applications of various genetically-encoded sensors and effectors in studying microglia-related biology and therapeutic interventions.
2022-04-06 | GSE197743 | GEO
Project description:The molecular basis of transgene susceptibility to silencing is poorly characterized in plants, thus we evaluated several transgene design parameters as means to reduce heritable sRNA-mediated transgene silencing. Analyses of Arabidopsis plants with transgenes encoding a microalgal polyunsaturated fatty acid (PUFA) synthase revealed that small RNA (sRNA)-mediated silencing, combined with the use of repetitive regulatory elements, led to aggressive transposable element (TE)-like silencing of canola-biased PUFA transgenes. Diversifying regulatory sequences and using native microalgal coding sequences (CDSs) with higher GC content improved transgene expression and resulted in remarkable trans-generational stability via reduced accumulation of sRNAs and DNA methylation. Further experiments in maize with transgenes individually expressing three Bacillus thuringiensis (Bt) crystal proteins tested the impact of CDSs recoding using different codon bias tables. Transgenes with the higher GC content exhibited increased transcript and protein accumulation. These results demonstrate that the sequence composition of transgene CDSs can directly impact silencing providing design strategies for increasing transgene expression levels and reducing risks of heritable loss of transgene expression.
2017-10-30 | GSE103037 | GEO
Project description:The molecular basis of transgene susceptibility to silencing is poorly characterized in plants, thus we evaluated several transgene design parameters as means to reduce heritable sRNA-mediated transgene silencing. Analyses of Arabidopsis plants with transgenes encoding a microalgal polyunsaturated fatty acid (PUFA) synthase revealed that small RNA (sRNA)-mediated silencing, combined with the use of repetitive regulatory elements, led to aggressive transposable element (TE)-like silencing of canola-biased PUFA transgenes. Diversifying regulatory sequences and using native microalgal coding sequences (CDSs) with higher GC content improved transgene expression and resulted in remarkable trans-generational stability via reduced accumulation of sRNAs and DNA methylation. Further experiments in maize with transgenes individually expressing three Bacillus thuringiensis (Bt) crystal proteins tested the impact of CDSs recoding using different codon bias tables. Transgenes with the higher GC content exhibited increased transcript and protein accumulation. These results demonstrate that the sequence composition of transgene CDSs can directly impact silencing providing design strategies for increasing transgene expression levels and reducing risks of heritable loss of transgene expression.
2017-10-30 | GSE76406 | GEO
Project description:A mutant screen was conducted in Arabidopsis that was based on deregulated expression of auxin-responsive transgenes. Two different tightly regulated (i.e., very low expression in the absence of auxin treatment and very high expression after exogenous auxin treatment) auxin-responsive promoters were used to drive the expression of both a ?-glucuronidase (GUS) reporter gene and a hygromycin phosphotransferase (HPH)?selectable marker gene. This screen yielded several mutants, and five of the mutations (axe1-1 to axe1-5) mapped to the same locus on chromosome 5. A map-based cloning approach was used to locate the axe1 mutations in an Arabidopsis RPD3-like histone deacetylase gene, referred to as HDA6. The axe1 mutant plants displayed increased expression of the GUS and HPH transgenes in the absence of auxin treatment and increased auxin-inducible expression of the transgenes compared with nonmutant control plants. None of a variety of endogenous, natural auxin-inducible genes in the mutant plants were upregulated like the transgenes, however. Results of treatment with the DNA methylation inhibitor 5-aza-2'-deoxycytidine suggest that the axe1 mutations affect transgene silencing; however, histone deacetylase inhibitors had no affect on transgene silencing in mutant or control plants. The specific effect of AtHDA6 mutations on the auxin-responsive transgenes implicates this RPD3-like histone deacetylase as playing a role in transgene silencing. Furthermore, the effect of AtHDA6 on transgene silencing may be independent of its histone deacetylase activity. A replicate experimental design type is where a series of replicates are performed to evaluate reproducibility or as a pilot study to determine the appropriate number of replicates for a subsequent experiments. Keywords: replicate_design
2007-08-09 | GSE7587 | GEO
Project description:A mutant screen was conducted in Arabidopsis that was based on deregulated expression of auxin-responsive transgenes. Two different tightly regulated (i.e., very low expression in the absence of auxin treatment and very high expression after exogenous auxin treatment) auxin-responsive promoters were used to drive the expression of both a ?-glucuronidase (GUS) reporter gene and a hygromycin phosphotransferase (HPH)?selectable marker gene. This screen yielded several mutants, and five of the mutations (axe1-1 to axe1-5) mapped to the same locus on chromosome 5. A map-based cloning approach was used to locate the axe1 mutations in an Arabidopsis RPD3-like histone deacetylase gene, referred to as HDA6. The axe1 mutant plants displayed increased expression of the GUS and HPH transgenes in the absence of auxin treatment and increased auxin-inducible expression of the transgenes compared with nonmutant control plants. None of a variety of endogenous, natural auxin-inducible genes in the mutant plants were upregulated like the transgenes, however. Results of treatment with the DNA methylation inhibitor 5-aza-2'-deoxycytidine suggest that the axe1 mutations affect transgene silencing; however, histone deacetylase inhibitors had no affect on transgene silencing in mutant or control plants. The specific effect of AtHDA6 mutations on the auxin-responsive transgenes implicates this RPD3-like histone deacetylase as playing a role in transgene silencing. Furthermore, the effect of AtHDA6 on transgene silencing may be independent of its histone deacetylase activity. *
2007-05-04 | E-SMDB-4012 | biostudies-arrayexpress
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2014-08-01 | GSE59952 | GEO
Project description:We report the application of Illumina paired-end RNA-seq approach for transcriptome of brain tissue in mice. By removing sequence-dependent bias and amplification noise using UMI-tools. The mapped reads of each sample were assembled using StringTie. After the final transcriptome was generated, StringTie and edgeR was used to estimate the expression levels of all transcripts. By obtaining a total of million paired-end reads of sequence from cerebral cortex tissue, we generated transcriptome profiles of mouse ischemic cortex in sham, 24 h after focal ischemia, 28 d after focal ischemia, with or without neuron-specific knockdown of TIPARP, respectively. We found 2017 differentially expressed genes (DEGs) between Sham+AAV-SYN-shRNA-Con and tMCAO+AAV-SYN-shRNA-Con group, and 516 DEGs between tMCAO+AAV-SYN-shRNA-Con and tMCAO+AAV-SYN-shRNA-TIPARP group at 24 h after stroke. In addition, we found 487 DEGs between Sham+AAV-SYN-shRNA-Con and tMCAO+AAV-SYN-shRNA-Con group, and 192 DEGs between tMCAO+AAV-SYN-shRNA-Con and tMCAO+AAV-SYN-shRNA-TIPARP group at 28 d after stroke. This study provides a detailed analysis of the underlying mechanisms of neuron-specific knockdown of TIPARP in neuronal injury and long-term effect, with biologic replicates, generated by RNA-seq technology.
2022-05-22 | GSE131712 | GEO