Project description:To elucidate the target genes of ArgR in Aeromonas veronii, we engineered an Aeromonas veronii strain that expresses the ArgR protein fused to a 3× FLAG tag, and FLAG antibodies were employed for the immunoprecipitation of DNA-protein complexes.
Project description:Aeromonas are ubiquitous inhabitants of both natural and anthropogenic aquatic ecosystems. Occasionally, Aeromonas also grows in drinking water distribution systems, which is highly undesired due to the pathogenicity of some members of this genus. The growth of Aeromonas in such highly oligotrophic environments is currently poorly understood. Possible nutrient sources are biopolymers. For example, chitin is the structural component of the exoskeleton of insects, some invertebrates and the cell walls of fungi which makes it one of the most abundant carbon and nitrogen sources in nature. In this study we demonstrate the ability of two Aeromonas strains, Aeromonas bestiarum and Aeromonas rivuli to efficiently grow on chitin. The secreted proteins confirm the presence of the functional hydrolytic enzymes that enable the efficient degradation and utilization of this abundant biopolymer. Further quantitative cellular proteomic study unravels the remarkable reorganization of the Aeromonas metabolism when switching to chitin as sole carbon and nitrogen source. This proves that Aeromonas is not only chitinolytic but also a chitinotrophic microorganism.
Project description:Retrons are bacterial genetic elements that encode a reverse transcriptase and, in combination with toxic effector proteins, can serve as antiphage defense systems. However, the mechanisms of action of most retron effectors, and how phages evade retrons, are not well understood. Here, we show that some phages can evade retrons and other defense systems by producing specific tRNAs. We find that expression of retron-Eco7 effector proteins (PtuA and PtuB) leads to degradation of tRNA-Tyr and abortive infection. The genomes of T5 phages that evade retron-Eco7 include a tRNA-rich region, including a highly expressed tRNA-Tyr gene, which confers protection against retron-Eco7. Furthermore, we show that other phages (T1, T7) can use a similar strategy, expressing a tRNA-Lys, to counteract a tRNA anticodon defense system (PrrC170).
Project description:Exon skipping is an effective strategy for the treatment of Duchenne Muscular Dystrophy (DMD). Natural exon skipping identified in several DMD cases can help with identifying novel therapeutic tools. Here, we demonstrate that CRISPR/Cas9 inactivation of the splicing factor Celf2a in a DMD-D44 background induces skipping of exon-45 and dystrophin rescue. Celf2a ablation could be compatible with life and curative since a DMD case with a milder symptomatology exists where exon-45 skipping occurs because of a Celf2a deficiency. We show that in this individual, Celf2a absence is due to inherited epigenetic silencing and that its repression is controlled by the lncRNA DUXAP8.
Project description:Phage therapy is a therapeutic approach to treat multidrug resistant infections that employs lytic bacteriophages (phages) to eliminate bacteria. Despite the abundant evidence for its success as an antimicrobial in Eastern Europe, there is scarce data regarding its effects on the human host. Here, we aimed to understand how lytic phages interact with cells of the airway epithelium, the tissue site that is colonized by bacterial biofilms in numerous chronic respiratory disorders. Using a panel of Pseudomonas aeruginosa phages and human airway epithelial cells derived from a person with cystic fibrosis, we determined that interactions between phages and epithelial cells depend on specific phage properties as well as physiochemical features of the microenvironment. Although poor at internalizing phages, the airway epithelium responds to phage exposure by changing its transcriptional profile and secreting antiviral and proinflammatory cytokines that correlate with specific phage families. Overall, our findings indicate that mammalian responses to phages are heterogenous and could potentially alter the way that respiratory local defenses aid in bacterial clearance during phage therapy. Thus, besides phage receptor specificity in a particular bacterial isolate, the criteria to select lytic phages for therapy should be expanded to include mammalian cell responses.
Project description:Absence of the dystrophin gene in Duchenne muscular dystrophy (DMD) results in the degeneration of skeletal and cardiac muscles. Owing to advances in respiratory medicine, cardiomyopathy has become a significant aspect of the disease. While CRISPR/Cas9 genome editing technology holds great potential as a novel therapeutic avenue for DMD, little is known about the efficacy of correction of DMD using the CRISPR/Cas9 system in mitigating the cardiomyopathy phenotype in DMD. To define the effects of CRISPR/Cas9 genome editing on structural, functional and transcriptional dysregulation in DMD-associated cardiomyopathy. We generated induced pluripotent stem cells (iPSCs) from a patient with a deletion of exon 44 of the DMD gene (ΔEx44) and his healthy brother. Here, we targeted exon 45 of the DMD gene by CRISPR/Cas9 genome editing to generate corrected DMD (cDMD) iPSC lines, wherein the DMD open reading frame was restored via reframing (RF) or exon skipping (ES). While DMD cardiomyocytes (CMs) demonstrated morphologic, structural and functional deficits compared to control CMs, CMs from both cDMD lines were similar to control CMs. Bulk RNA-sequencing of DMD CMs showed transcriptional dysregulation consistent with dilated cardiomyopathy, which was mitigated in cDMD CMs. We then corrected DMD CMs by adenoviral delivery of Cas9/gRNA and showed that postnatal correction of DMD CMs reduces their arrhythmogenic potential. Single-nucleus RNA-sequencing of hearts showed reduced transcriptional dysregulation in CMs and fibroblasts in corrected mice compared with DMD mice, consistent with reduced histopathologic changes.We show that CRISPR/Cas9-mediated correction of DMD ΔEx44 mitigates structural, functional and transcriptional dysregulation consistent with dilated cardiomyopathy irrespective of how the protein reading frame is restored. We show that these effects extend to postnatal editing in iPSC-CMs and mice. These findings provide key insights into the utility of genome editing as a novel therapeutic for DMD-associated cardiomyopathy.
Project description:The Dystrophin gene (DMD) is the largest gene in the human genome, mapping on Xp21, spanning 2.2Mb and accounting for approximately 1% of the entire human genome. Mutations in this gene cause Duchenne and Becker muscular dystrophy, X-linked dilated cardiomyopathy, and other milder muscle phenotypes. Beside the remarkable number of reports describing dystrophin gene expression and the pathogenic consequences of the gene mutations in dystrophinopathies, the full scenario of the DMD transcription dynamics remains however, poorly understood. Considering that the full transcription of the DMD gene requires about 16 hours, we have investigated the activity of RNA Polymerase II along the entire DMD locus within the context of specific chromatin modifications using a variety of chromatin-based techniques. Our results unveil a surprisingly powerful processivity of the RNA pol II along the entire 2.2 Mb of the DMD locus with just one site of pausing around intron 52. More importantly, epigenetic marks highlighted the existence of four novel cis-DNA elements, two of which, located within intron 34 and exon 45, appear to govern the architecture of the DMD chromatin with implications on the expression levels of the muscle dystrophin mRNA. Overall, our findings provide a global view on how the entire DMD locus is dynamically transcribed by the RNA pol II and shed light on the mechanisms involved in dystrophin gene expression control, which can positively impact on the optimization of the novel ongoing therapeutic strategies for dystrophinopathies.
Project description:Rationale – Absence of the dystrophin gene in Duchenne muscular dystrophy (DMD) results in the degeneration of skeletal and cardiac muscles. Owing to advances in respiratory medicine, cardiomyopathy has become a significant aspect of the disease. While CRISPR/Cas9 genome editing technology holds great potential as a novel therapeutic avenue for DMD, little is known about the efficacy of correction of DMD using the CRISPR/Cas9 system in mitigating the cardiomyopathy phenotype in DMD. Objective – To define the effects of CRISPR/Cas9 genome editing on structural, functional and transcriptional dysregulation in DMD-associated cardiomyopathy. Methods and Results – We generated induced pluripotent stem cells (iPSCs) from a patient with a deletion of exon 44 of the DMD gene (ΔEx44) and his healthy brother. Here, we targeted exon 45 of the DMD gene by CRISPR/Cas9 genome editing to generate corrected DMD (cDMD) iPSC lines, wherein the DMD open reading frame was restored via reframing (RF) or exon skipping (ES). While DMD cardiomyocytes (CMs) demonstrated morphologic, structural and functional deficits compared to control CMs, CMs from both cDMD lines were similar to control CMs. Bulk RNA-sequencing of DMD CMs showed transcriptional dysregulation consistent with dilated cardiomyopathy, which was mitigated in cDMD CMs. We then corrected DMD CMs by adenoviral delivery of Cas9/gRNA and showed that postnatal correction of DMD CMs reduces their arrhythmogenic potential. Single-nucleus RNA-sequencing of hearts showed reduced transcriptional dysregulation in CMs and fibroblasts in corrected mice compared with DMD mice, consistent with reduced histopathologic changes. Conclusions – We show that CRISPR/Cas9-mediated correction of DMD ΔEx44 mitigates structural, functional and transcriptional dysregulation consistent with dilated cardiomyopathy irrespective of how the protein reading frame is restored. We show that these effects extend to postnatal editing in iPSC-CMs and mice. These findings provide key insights into the utility of genome editing as a novel therapeutic for DMD-associated cardiomyopathy.
Project description:Duchenne muscular dystrophy (DMD) is caused by mutations in the X-linked dystrophin (DMD) gene. The absence of dystrophin protein leads to progressive muscle weakness and wasting, disability and death. To establish a tailored large animal model of DMD, we deleted DMD exon 52 in male pig cells by gene targeting and generated offspring by nuclear transfer. DMD pigs exhibit absence of dystrophin in skeletal muscles, increased serum creatine kinase levels, progressive dystrophic changes of skeletal muscles, impaired mobility, muscle weakness, and a maximum life span of 3 months due to respiratory impairment. To address the accelerated development of muscular dystrophy in DMD pigs as compared to human patients, we performed a genome-wide transcriptome study of M. biceps femoris samples from 2-day-old and 3-month-old DMD and age-matched wild-type pigs. The transcriptome changes in 3-month-old DMD pigs were in good accordance with the findings of gene expression profiles in human DMD, reflecting the processes of degeneration, regeneration, inflammation, fibrosis, and impaired metabolic activity. The transcriptome profile of 2-day-old DMD pigs pointed towards increased protein and DNA catabolism, reduced extracellular matrix formation and cell proliferation and showed similarities with transcriptome changes induced by exercise injury in muscle. Our transcriptome studies provide new insights into congenital changes associated with dystrophin deficiency and secondary complications arising during postnatal development. Thus the DMD pig is a useful model to determine the hierarchy of physiological derangements in dystrophin-deficient muscle. 13 samples, two conditions, two age-groups, 3-4 biological replicates