Dissertations / Theses on the topic 'Correction génique (CRISPR/Cas9)'
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Rabai, Aymen. "Correction de l'ADN in vitro et in vivo comme thérapie personnalisée pour les myopathies congénitales." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAJ117.
Genome editing with the CRISPR/Cas9 technology has emerged recently as a potential strategy for therapy in genetic diseases. For dominant mutations linked to gain-of-function effects, allele-specific correction may be the most suitable approach. Here we tested allele-specific inactivation or correction of a heterozygous mutation in the Dynamin 2 (DNM2) gene causing the autosomal dominant form of centronuclear myopathies (CNM). Truncated single guide RNAs targeting specifically the mutated allele were tested on cells derived from a mouse model and patients. The mutated allele was successfully targeted in patient fibroblasts and Dnm2R465W/+ mouse myoblasts, and clones were obtained with both precise genome correction or inactivation. Dnm2R465W/+ myoblasts showed an alteration in transferrin uptake and autophagy. Specific inactivation or correction of the mutated allele rescued these phenotypes. The mutated allele was also successfully targeted in Dnm2R465W/+ mouse muscles. These findings illustrate the potential of CRISPR/Cas9 to target and correct heterozygous point mutations leading to a gain-of-function effect in an allele-specific manner
Rabai, Aymen. "Correction de l'ADN in vitro et in vivo comme thérapie personnalisée pour les myopathies congénitales." Electronic Thesis or Diss., Strasbourg, 2018. http://www.theses.fr/2018STRAJ117.
Genome editing with the CRISPR/Cas9 technology has emerged recently as a potential strategy for therapy in genetic diseases. For dominant mutations linked to gain-of-function effects, allele-specific correction may be the most suitable approach. Here we tested allele-specific inactivation or correction of a heterozygous mutation in the Dynamin 2 (DNM2) gene causing the autosomal dominant form of centronuclear myopathies (CNM). Truncated single guide RNAs targeting specifically the mutated allele were tested on cells derived from a mouse model and patients. The mutated allele was successfully targeted in patient fibroblasts and Dnm2R465W/+ mouse myoblasts, and clones were obtained with both precise genome correction or inactivation. Dnm2R465W/+ myoblasts showed an alteration in transferrin uptake and autophagy. Specific inactivation or correction of the mutated allele rescued these phenotypes. The mutated allele was also successfully targeted in Dnm2R465W/+ mouse muscles. These findings illustrate the potential of CRISPR/Cas9 to target and correct heterozygous point mutations leading to a gain-of-function effect in an allele-specific manner
Martineau, Sabrina. "Etude des mécanismes moléculaires de l'épidermolyse bulleuse simple à partir de cellules souches humaines induites à la pluripotence." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASQ020.
Epidermolysis bullosa simplex (EBS) is a skin disorder caused mainly by dominant mutations in genes coding for keratin 5 (KRT5) or 14 (KRT14) genes. It is characterized by the presence of blisters caused by epidermal detachment, and by other complications such as cutaneous inflammation. From a genetic point of view, the mutations will alter the assembly of the keratin intermediate filament network in basal keratinocytes of the epidermis, leading to cell cytolysis and the formation of intra-epidermal blisters. Currently no effective therapeutic approach it is available. Understanding of the disease and the development of therapies have been hampered by the lack and limitations of relevant human cell and mouse models.So, the general aim of my thesis was to exploit the properties of human induced pluripotent stem cells (hiPSc) to modelling EBS. For this purpose, we generate hiPSc-derived keratinocytes from EBS patients carrying KRT5 mutations (Ker-EBS), and from healthy patients (Ker-WT). Comparison of Ker-EBS and Ker-WT enabled to show that Ker-EBS recapitulates the main phenotypes associated with EBS, namely decreased cell proliferation, increased cell migration, altered signalling pathways (ERK and JNK), as well as aggregates of intermediate keratin filaments in the cytoplasm, as observed in primary EBS keratinocytes. These results demonstrate that our hiPSc-derived cell model is relevant for study EBS.In order to identify new molecular mechanisms, a trancriptomic analysis comparing Ker-EBS with Ker-WT revealed 138 deregulated genes, revealing an enrichment in processes linked to the extracellular matrix, DNA packaging and the inflammatory response. As the inflammatory component in EBS has been poorly described, my next step was to study the pro-inflammatory cytokine phenotype. Thus, we were able to demonstrate increased expression of IL-1α, IL-1β, IL-6, IL-8 (CXCL8), CXCL5, CXCL10, CXCL11, CCL5 in Ker-EBS, at RNA level under basal or IFNy-stimulated conditions to mimic a pro-inflammatory context. Only the chemokines CXCL10 and CXCL11 are secreted at high concentrations in the culture supernatants of stimulated and unstimulated Ker-EBS, demonstrating the involvement of these cytokines in EBS.In parallel, in order to avoid biases due to genetic background, gender, patient age and epigenetics, we generated an isogenic Ker-EBS line (corrected Ker-EBS) using the CRISPR-Cas9 technique. We were thus able to demonstrate that the corrected Ker-EBS line showed a restoration of the expression level of the pro-inflammatory cytokines mentioned above, to a level close to that of Ker-WT, confirming a direct link between mutations in the KRT5 gene and the pro-inflammatory signature.In conclusion, our new cellular model enabled us to reproduce the pathological phenotypes known in the literature, and to demonstrate deregulation of pro-inflammatory cytokine expression in EBS, notably CXCL10 and CXCL11. Taken together, these results make this model a relevant tool to allow a better understanding of the molecular mechanisms associated with the pathology, particularly the inflammatory component, paving the way for new therapeutic approaches
Cullot, Grégoire. "Génotoxicité des systèmes CRISPR-Cas9." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0344.
Gene therapy is a promising therapeutic strategy for the monogenic diseases treatment. If the first approaches, called additive, have relied on the use of viral vectors, a growing share is now turning to gene editing. Less than a decade after its characterization, the CRISPR-Cas9 system has moved gene editing to a clinical stage. However, in the same period of time, several questions have been raised regarding the genotoxicity that can be induced by Cas9. An emerging literature points to the risk of genotoxicity at the targeted site. The thesis work presented here is part of this theme. The first part of the study aimed to describe the genotoxicity induced by a single double-stranded break made by Cas9. Characterization of the effects was done both at the nucleotide level, by monitoring the HDR / InDels balance, but also at the chromosome scale. The monitoring of chromosomal integrity has brought to light a new risk of genotoxicity that was not characterized. A sensitive and specific detection system for this risk has been developed to further characterize it. The second objective was to address the limitations of unwanted genotoxicity by developing a safer and more efficient gene editing method through the use of a single single-stranded breakage by Cas9D10A-nickase
Raas, Quentin. "Inactivation génique des transporteurs ABC peroxysomaux ABCD1 et ABCD2 dans les cellules microgliales BV-2 : étude de la physiopathogenèse de l’adrénoleucodystrophie liée à l’X." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCI011/document.
X-linked adrenoleukodystrophy (X-ALD) is a severe neurodegenerative disorder characterized by very-long-chain fatty acid (VLCFA) accumulation resulting from a peroxisomal β-oxidation defect. The disease is caused by mutations in the ABCD1 gene, which encodes for a peroxisomal half ABC transporter predicted, like its closest homologue ABCD2, to participate in the entry of VLCFA-CoA into the peroxisome, the unique site of their β-oxidation. Progress in understanding the physiopathogenesis of X-ALD suffers from the lack of appropriate cell and animal models. Since peroxisomal defects in microglia seem to be a key element of the onset of the disease, we generated four microglial cell lines unable to transport and/or β-oxidize VLCFA into the peroxisome. BV-2 microglial cells were engineered with CRISPR-Cas9 to generate four microglial cell lines deficient in ABCD1, ABCD2, both ABCD1 and ABCD2 or ACOX-1 (the first rate-limiting enzyme of the peroxisomal β-oxidation system). Biochemical defects and lipid content changes associated with VLCFA accumulation but also fatty acids and cholesterol changes were identified in deficient microglia. Ultrastructural investigations confirmed cytosolic lipid inclusions and an increased number of peroxisome and mitochondria. Transcriptomic profiles of deficient microglia are indicative of an impaired plasticity and an impaired capacity to operate the metabolic shift required upon an inflammatory stimulation. Peroxisomal defect is likely to affect phagocytosis and antigen presentation capacity of microglia. Peroxisomal lipid metabolism defect is also suggested to modify cell membranes organization. Altogether, these novel mutant cell lines represent a promising model that should permit identification of new therapeutic targets for this complex neurodegenerative disease
Prat, Florence. "Les solutions pour prévenir de la génotoxicité du système CRISPR-Cas9." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0322.
CRISPR-Cas9 system has revolutionized genetic world. Nowadays, it is used in various research domains as medicine, agronomy, environment… It is also involved in clinic. However, for a few years, more and more studies have underlined the Cas9 genotoxicity risks. As the first studies focused on the system lack of specificity and on its off-target risks, solutions were brought. Now, new ascertainments emphasize the on-target genotoxic risks. Indeed, non-desired insertions / deletions at the locus in HDR experiments, sequence inversions, large chromosomic truncations were described. The thesis work presented here, aims at finding solutions against these on-target genotoxic risks. In a first time, we have developed solutions in cell lines and hematopoietic stem cells with the nickase system development, and then we have focused on human induced pluripotent stem cells with the use of an allele-specific guide. Finally, we have worked out in sensitive detection genotoxic risks system in immortalized diploid cells to characterized them better. Quality controls must be set up to a correct use of this new biologic revolutionary tool and its limits must be known to controlled them better
Dias, Florencio Leite Gabriella. "Recombinant Adeno-Associated Viruses : process development and gene transfer application for muscular dystrophy." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV051/document.
The interest of recombinant Adeno-Associated Virus (rAAV) vectors for research and clinical purposes in the treatment of genetic diseases have led to the rapid evolution of methods for AAV production in the last two decades (Ayuso et al., 2010). Their broad in vivo biodistribution and long-term efficacy in postmitotic tissues make them good candidates for numerous gene transfer applications. In addition, the specificity of the treatment can be increased when the right serotype is chosen to target a specific tissue. Among the production methods currently in use, tri-transfection of human embryonic kidney 293 (HEK293) cells remains the most popular for research scale; and rAAV production mediated by baculoviruses for larger scales. The increasing importance of viral vectors in the practical application of gene therapy demands the improvement of production processes, especially when it concerns the yields and purity of the final product. My work during these four years was focused in two main points: (1) improve biotechnological processes employed in rAAV production for research and pre-clinical study scales and (2) test in vitro and in vivo the applications for rAAV in the field of genome editing. Gene-editing mediated by engineered nucleases offers new hopes for the treatment of several monogenic inherited diseases. Recently discovered, the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) Cas9 system provides important tools needed to correct by homology-directed repair mutations. Our canonical model is the mdx mouse, a naturally occurring animal model of Duchenne Muscular Dystrophy (DMD). DMD mutations, which lead to the absence of the protein dystrophin, results in a progressive and fatal myopathy. Several strategies, from pharmacological to exon-skipping strategies, have attempt to revert the phenotype and slow down the disease progress, however results are not yet satisfactory. This new and powerful genome editing tool can be vectorized by rAAV. Results for the first part were published in 2015 and 2016 and will be presented in the form of articles and for the second part I will present preliminary results and perspectives for the work that will be continued in the lab
Girard, Lindsay. "Correction de mutations causant l'épidermolyse bulleuse simplex par recombinaison homologue avec la technologie CRISPR/Cas9." Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/35775.
Dib, Carla. "développement d'approches de correction des myoblastes issus de patients atteints de la dystrophie facio-scapulo-humérale." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS224.
Facio-Scapulo-Humeral dystrophy is characterized by progressive and asymmetrical muscle weakness. It mainly affects the facial, scapular and humeral muscles. The association of several epigenetic events with three genetic factors of the subtelomeric region of chromosome 4 results in a chromatin organization modification making it permissive to the aberrant expression of genes in the 4q35 region. FSHD myoblasts exhibit differentiation defects in vitro and dysregulations in major pathways such as the cellular response to oxidative stress and myogenic differentiation. The limitations of cell therapy and the complex genetic and epigenetic interplay in FSHD leave it, till now, incurable. However advances in cellular and genetic therapies of myopathies open up new horizons for future applications in the FSHD context. The thesis work is structured around three themes. First, we demonstrate the feasibility of phenotypic and functional correction of FSHD myotubes in vitro by fusing 50% of normal myoblasts with FSHD myoblasts. Next, we evaluate two genomic editing approaches. In the first one, we target the site of attachment of chromosome 4 to the nuclear matrix, FR-MAR with the CTCF protein using the CRISPR / dCas9 system for the purpose of restoring the chromatin organization and the insulating function of FR-MAR. In the second one, we exchange the homologous regions 4q35 and 10q26 by translocation in order to correct the FSHD myoblasts as the three genetic factors of the 4q35 locus are pathogenic only on a genetic background linked to chromosome 4. Finally, we study the role of the oxidative stress in the FSHD
Iyombe, Jean-Paul. "Correction du gène de la dystrophine avec la méthode CRISPR induced deletion (CinDel)." Doctoral thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/35026.
Duchenne Muscular Dystrophy (DMD) is an X-linked genetically recessive genetic disorder. It affects 1 boy out of 3500 male births. The boy with the disorder presents walking disorders at the age of 3-4 years and loses it around the age of 11. Death occurs around 18-30 years of age from cardiopulmonary complications. To date, there is no effective cure for this serious disease. We have developed a gene therapy approach called CRISPR-induced deletion (CinDel) to correct the mutated DMD gene. It uses two gRNAs that target the exons preceding and following the deletion responsible for the frame shift. The recognition of the target sites by the two gRNAs allows the recruitment of the Cas9 nuclease, which generates double-strand breaks. The exonic and intronic sequences located between the two cuts are then deleted and the remains of the exons are fused by Non-Homologous End Joining (NHEJ) to produce a hybrid exon and restore the reading frame and to allow the synthesis of the truncated dystrophin with correct SLR structure and heptads. The CinDel approach was used in this project to correct the mutated DMD gene in the myoblasts of a patient with a 51-53 deletion. Exons 50 and 54 were targeted by SpCas9 and two gRNAs and to produce double strand breaks, delete the sequences between the two cleavage sites and produce a hybrid exon 50-54 by NHEJ. This restored the normal reading frame and allowed the expression of truncated dystrophin in the patient's myotubes. The approach also made it possible to correct in vivo the mutated DMD gene in the animal model, the transgenic mouse with a human DMD gene having a deletion of exon 52 (del52hDMD) using an AAV9 viral vector containing the SpCas9 gene and two ARNgs. To verify the location with respect to the sarcolemma of truncated dystrophin with or without a correct SLR structure and heptads, we electroporated the Tibialis anterior muscles of mdx/mdx mice with the plasmids encoding the normal or the truncated dystrophin gene fused with the eGFP gene. The results of this experiment show that truncated and normal dystrophins were well localized under sarcolemma. In order to effectively repress the SpCas9 gene and avoid its prolonged expression that may be the basis of random and unexpected (off-target effects) cuts in the genome, we have developed a method of repression called molecular Hara-Kiri. It uses the CinDel method and consists of targeting two regions of the SpCas9 gene with two gRNAs. Recruiting nuclease allows it to cut its own gene (Hara-Kiri). The sequence between the two cleavage sites is deleted. The residues of the SpCas9 gene are then joined by NHEJ generating a TAA stop codon at the junction point. This approach effectively repressed the SpCas9 gene in vitro and in vivo.
Bou, saada Yara. "Des mécanismes moléculaires pathologiques aux stratégies de correction génomique in vitro de la Dystrophie Facio-Scapulo-Humérale." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS241.
Facioscapulohumeral dystrophy (FSHD) is one of the most common genetic myopathies characterized by a progressive and asymmetric weakening of a specific group of skeletal muscles, typically facial, shoulder girdle and upper arms muscles. FSHD is a multifactorial disease that results from the combination of genetic and epigenetic events mapped at the 4q35 locus. These genetic and epigenetic alterations lead to chromatin relaxation and the subsequent overexpression of the majority of 4q35 genes, notably DUX4, the major actor in FSHD pathology. These genomic alterations lead to molecular and cellular defects observed in vitro. Cultured-FSHD myoblasts show a distinct transcription profile, they exhibit morphological differentiation defects and are sensitive to oxidative stress. Several aspects of the disease remain poorly understood, and the elaboration of an appropriate therapeutic strategy is limited by the complexity of this myopathy. However, the discovery of genome editing tools and their successful therapeutic applications in vitro and in animal models of several human diseases, including myopathies, open doors to potential therapeutic strategies for FSHD.This work highlighted the involvement of DNA damage and oxidative stress in the pathophysiology of FSHD, by revealing their constitutive presence in FSHD myoblasts, their link to DUX4 expression and their participation in morphological defects of FSHD myotubes observed in vitro. The second part of this work was aimed at developing genome- and epigenome-editing tools capable of specifically targeting one of the genetic events causing FSHD, a pathogenic variant 4qA161 that contains an insulator and a nuclear matrix attachment site (FR-MAR). These engineered tools will be then used to develop in vitro therapeutic strategies, with the intention of restoring the insulator activity of FR-MAR and the chromatin organization of 4q35 locus
Li, Hongmei. "Precise Correction of the Dystrophin Gene in Duchenne Muscular Dystrophy Patient iPS Cells by TALEN and CRISPR-Cas9." Kyoto University, 2015. http://hdl.handle.net/2433/199179.
Giada, Beligni. "Application of the CRISPR-Cas9 genome editing approach for the correction of the p.Gly2019Ser (c.6055G>A) LRRK2 variant in Parkinson Disease." Doctoral thesis, Università di Siena, 2022. https://hdl.handle.net/11365/1220257.
Estève, Julie. "Transfert de gènes dans les cellules souches pluripotentes induites : application à la thérapie génique de l'hyperoxalurie primitive de type 1." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0280/document.
Primary hyperoxaluria type 1 (or PH1) is an inherited metabolic disorder related to the deficiency of the hepatic AGT enzyme (alanine:glyoxylate aminotransferase), which is encoded by the AGXT gene. In PH1 patients, this deficiency leads to oxalate overexcretion by liver, followed by urine filtration and complexation with calcium to form massive calcium-oxalate nephrolithiasis potentially leading to chronic renal failure. The only available curative treatment is combined hepatorenal allogeneic engraftment, which is currently limited by the availability of transplant donors, significant morbidity and mortality, and the need for long-term immunosuppressive treatment. The aim of our research project is to develop gene therapy for PH1, consisting in engraftment of genetically corrected autologous liver cells. Considering that adult hepatocytes are hardly available and expandable in vitro, we chose to explore the use of induced pluripotent stem cells (iPSCs) to produce human liver cells for application in regenerative medicine. We derived and characterized iPSC lines from PH1 patient fibroblasts after transient expression of reprogramming factors delivered by Sendai virus vectors. We developed two additive gene therapy strategies by inserting a minigene encoding an optimized AGXT cDNA sequence using (1) a lentiviral vector designed for liver-specific expression and (2) homologous recombination process at the AAVS1 locus favoured by the targeted DNA cutting system “CRISPR/Cas9”. Finally, we highlighted therapeutic cassette expression after hepatic differentiation of genetically corrected iPSCs. These results pave the way for regenerative medicine for PH1 by transplantation of genetically modified autologous hepatocyte-like cells derived from patient-specific iPSCs
Mianné, Joffrey. "Thérapie génique par CRISPR/Cas9 pour corriger des épithéliums bronchiques dérivés de cellules souches pluripotentes induites (iPSCs) de patients atteints de dyskinésie ciliaire primitive (DCP) : une preuve de concept." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTT045.
Primary Ciliary dyskinesia (PCD) is a rare and heterogeneous genetic disorder affecting the structure and function of motile cilia. In the airway epithelium, impaired ciliary motion results in chronic airway infections responsible for progressive and definitive decline of lung functions. There is currently no effective treatment for PCD, and research is limited by the lack of convenient models to study this disease and investigate innovative therapies.In this context, the main goals of this thesis are: 1) to develop a new in vitro PCD model based on the directed differentiation of patient-derived or genetically-engineered induced pluripotent stem cells (iPSC) into multiciliated airway epithelium, and 2) to use this model to investigate the potential of an innovative CRISPR/Cas9 gene therapy approach.To this aim, we have derived two iPSC lines, one from an healthy individual and a second from a PCD patient harbouring compound heterozygous mutations in the CCDC40 gene. Using the “healthy” iPSC line and the CRISPR/Cas9 technology we have generated isogenic knock-out controls for three PCD genes including CCDC40, DNAH5 and MCIDAS. In parallel, using the CRISPR/Cas9 technology and the homology directed repair approach, we have corrected the patient-derived iPSC line. By applying our optimized differentiation protocol to these cell lines, we are efficiently generating functional multiciliated airway epithelium recapitulating the ciliary phenotypes in function of the genotype. Furthermore, this new model has allowed us to investigate the potential of a CRISPR/Cas9-mediated reframing gene therapy approach to rescue ciliary phenotype in the patient line.In conclusion, the new model developed in this work could represent a major tool for in vitro PCD modelling. This model will be of particular interest for investigating the feasibility and efficacy of personalized therapies directly on the relevant human tissue. Our pipeline could therefore accelerate the development and translation of new therapeutics for PCD and other lung diseases
Rousset, Francois. "CRISPRi screens in bacterial genomics." Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS373.
Advances in sequencing technologies over the past decade have significantly expanded the field of bacterial genomics. In this context, new experimental methods are still required to better understand gene function. The discovery of CRISPR-Cas systems in bacterial adaptive immunity led to the development of a variety of biotechnological tools to target DNA in a sequence-specific manner. In particular, the dCas9 protein can be guided towards a target DNA sequence by short RNAs called sgRNAs to inhibit gene expression in a mechanism called CRISPRi. The present thesis describes the development of a high-throughput screening method based on the pooled synthesis and cloning of sgRNAs libraries. We first showed that CRISPRi screens can confidently predict essential genes in E. coli. We also exploited this method during infection by different bacteriophages to determine which host genes are required for a successful infection. While most genomics studies rely on model strains which fail to represent the genetic diversity of the species, we next developed a CRISPRi platform that is compatible with most isolates from E. coli and closely-related species. A sgRNA library targeting ~3,300 persistent genes from the E. coli species was designed and implemented in a collection of natural isolates to determine the impact of genetic diversity on the essentiality of core genes. We demonstrated how horizontally-transferred genes can modulate core gene essentiality. Altogether, this work shows the potential of high-throughput CRISPRi screens in bacterial genomics
Jayavaradhan, Rajeswari. "Optimization of Gene Editing Approaches for Human Hematopoietic Stem Cells." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1543919940219677.
Hamouri, Fatima. "Contrôle optique de l'activité de protéines et de l'expression de gènes, par photo-activation du cyclofène cagé, pour l’étude de l’initiation du cancer." Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS235.
The zebrafish has become an increasingly popular and valuable cancer model over the past decades. While most of these models are generated by expressing mammalian oncogenes under tissue-specific promoters, here we describe a method that allows for the precise optical control of oncogene expression or inactivation in live zebrafish. Thus, this technique allows for the induction of tumor phenotypes by activating the constitutive expression of a typical human oncogene, KRASG12V, in selected tissues and single cells without tissue-specific promoters in live zebrafish. We also demonstrate the optical control of oncogene expression as KRASG12V, CMYC and BRAFV600E as well as the control of the expression and the activity of the CRISPR-Cas9 system. In addition, it should be noted that accurate manipulation of gene expression is essential to understand most biological processes. Therefore, our work presents a novel approach to initiate and study cancer in zebrafish. Finally, it is also worth noting that the high spatio-temporal resolution of this method makes it a valuable tool for studying cancer initiation from single cells
Sürün, Duran [Verfasser], Beatrix [Akademischer Betreuer] Süß, M. Cristina [Akademischer Betreuer] Cardoso, and Harald von [Akademischer Betreuer] Melchner. "High Efficiency Gene Correction in Hematopoietic Cells by Donor Template-free CRISPR/Cas9 Genome Editing / Duran Sürün ; Beatrix Süß, M. Cristina Cardoso, Harald von Melchner." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2018. http://d-nb.info/1153546396/34.
Sevestre, François. "Mise en oeuvre de l’édition génomique par CRISPR/Cas9 pour l’étude fonctionnelle des amidon-synthases chez la pomme de terre (Solanum tuberosum)." Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1S109.
The potato is a plant of the solanaceae family that is cultivated for its tubers. This reserve organ is a staple food for many populations around the world. It is rich in starch, a polysaccharide stored in the form of insoluble granules in specialized organelles: the amyloplasts. Starch metabolism is complex and finely regulated by many enzymes including starch synthases. These enzymes are responsible for creating new α-1,4-type O-glucosidic bonds. Several isoforms of starch synthases have already been characterized in plants (GBSS, SS1, SS2, SS3, SS4 and SS5). In addition, a new isoform called SS6 (Starch Synthase 6) has recently been identified in the laboratory by proteomic analysis in potato. Functional genomics in potato were, until recently, limited by the tetraploid character and the uniquely vegetative mode of reproduction of cultivated varieties. The recent emergence of site-directed mutagenesis and in particular of the CRISPR/Cas9 system removes this barrier, in particular allowing the targeted inactivation of genes.First, we sequenced the genome of the tetraploid potato variety Désirée. This analysis revealed a strong intrinsic polymorphism. I used this data to map polymorphisms and to develop a target design assistance tool in potato genomic editing. I then characterized the starch from plants previously mutated at the GBSS locus by CRISPR/Cas9 and demonstrated an accumulation of SS2 and GWD in the starch. Consequently, the phosphate contents, in particular at the C6 position of the glucose residues, are increased. These results open new perspectives in understanding the metabolism and assembly of enzymes with starch polysaccharides.We have also shown that SS6 is present in dicotyledons except Brassicaceae. The recombinant version of the potato protein expressed in E.coli is active on glycogen and allows the elongation of glucans from DP2 to DP5. In addition, the protein fused with GFP and expressed in planta is localized in the amyloplast, confirming the observations initially made in the laboratory during the characterization of the proteome associated with potato starch. I studied the function of SS6 in planta by producing KO lines for the corresponding gene by CRISPR/Cas9 and by overexpressing the native protein under the control of the 35S promoter. Overexpression of the gene causes a decrease in the mean diameter of the starch grains at the late stage of tuber development suggesting that the enzyme is involved in the regulation of the size and therefore supposedly the number of starch grains. We also observed slight changes in starch structure in the ss6- knockout lines. Indeed, the amylopectin of the mutant lines shows a decrease in glucans from DP6 to DP14 and an increase in glucans from DP15 to DP21. Although subtle, these changes corroborate the activity observed with the recombinant protein in vitro. Inactivation of SS6 may be partially offset by the activity of other redundant starch synthases, as has been observed in many cases and in many species. The generation of combinations of mutations for SS6 and other starch synthase genes will provide insight into the role of this enzyme in the metabolism of starch storage
Nasri, Masoud [Verfasser]. "CRISPR/Cas9-based correction of ELANE mutations in severe congenital neutropenia (CN) patients with no response to G-CSF and high risk to develop leukemia / Masoud Nasri." Tübingen : Universitätsbibliothek Tübingen, 2021. http://d-nb.info/1230796436/34.
Poggi, Lucie. "Gene editing approaches of microsatellite disorders : shortening expanded repeats." Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS412.
Microsatellite disorders are a specific class of human diseases that are due to the expansion of repeated sequences above pathological thresholds. These disorders have varying symptoms and pathogenic mechanisms, caused by the expanded repeat. No cure exists for any of these dramatic conditions. This thesis is investigating new gene editing approaches to remove pathological expansions in the human genome. In a first part, a yeast-based screen was constructed to identify potent CRISPR-associated nucleases that can cut these microsatellites. The second part focuses on myotonic dystrophy type 1 (DM1), which is due to and expanded CTG repeat tract located at the 3’UTR of the DMKP gene. A nuclease, TALENCTG was designed to induce a double strand break into the CTG repeats. It was previously shown to be active in yeast cells, inducing contractions of CTG repeats from a DM1 patient integrated into the yeast genome. The TALEN was tested in DM1 patient cells. The nuclease was found to trigger some contraction events in patient cells. In vivo experiments were carried out in a mouse model of myotonic dystrophy type 1 containing a human genomic fragment from a patient and 1000 CTG. Intramuscular injections of recombinant AAV encoding the TALENCTG revealed that the nuclease is toxic and/or immunogenic in muscle cells in the tested experimental conditions. Finally, the reporter assay integrated in yeast to screen nucleases was transposed in HEK293FS cell line. The integrated cassette contains a CTG expansion from a myotonic dystrophy type 1 patient flanked by two halves of GFP genes. This system would enable to find nucleases active in human cells
Foster, Robert Graham. "Development of a modular in vivo reporter system for CRISPR-mediated genome editing and its therapeutic applications for rare genetic respiratory diseases." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33040.
Rodrigues, Amélie. "Modélisation d'une forme de rétinite pigmentaire et validation d'une approche de thérapie génique, à l'aide de cellules rétiniennes dérivées de cellules iPS humaines." Thesis, Sorbonne université, 2021. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2021SORUS520.pdf.
Generation of retinal cells from human iPS cells offers the opportunity to study the effects of specific disease-causing mutations in an in vitro human system. Our project consisted of modeling specific form of Retinits Pigmentosa (RP) using patient iPS cells. We first optimized a differentiation protocol to obtain retinal organoids with a structural organization closer to the retina in vivo, allowing advanced photoreceptor maturation. Using this tool, we were able to fully recapitulate the RP phenotype (degeneration of rods and cones), observed in patients with mutation in RHODOPSINE gene, coding for the visual pigment. Then, we used the same approach to understand the pathogenicity of RP related to mutations in PRPF31 gene, coding for a splicing factor. Retinal organoids summarized the degeneration of mature rods and secondary loss of cones, as observed in patients. Furthermore, PRPF31-mutated retinal pigmented epithelial cells exhibited also structural and functional defective phenotype. These retinal degenerative phenotypes are correlated with a lower level expression of PRPF31 protein, linking causal mutations to an haploinsufficiency mechanism. We thus have developed a gene augmentation strategy, bringing an additional wild type copy of PRPF31 through CRISPR/Cas9 or using an AAV vector, that both allowed the rescue of retinal cell degeneration
Pérez, Rico Yuvia Alhelí. "Zebrafish as a model to determine conserved gene regulatory mechanisms in vertebrates." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS535.pdf.
Super-enhancers and CTCF are considered as central players in the organization of mammalian genomes that directly impact the regulation of gene expression. Here, to gain insight into their functional conservation, analyses of super-enhancers and CTCF in zebrafish were performed. Super-enhancers annotated in zebrafish show high cell and tissue specificity, and the main difference identified when compared to mammalian super-enhancers is their distribution relative to transcription start sites. Conservation analyses indicate that super-enhancers do not have higher sequence conservation than typical enhancers. By restricting the analysis to those super-enhancers associated with orthologs, a subset of super-enhancers that have higher sequence conservation than the rest was identified. Comparison of the expression patterns driven by constitutive regions of two of these super-enhancers enabled the identification of regions controlling similar expression patterns in spite of no evident sequence conservation. Analyses of CTCF peaks that overlap promoters indicate a correlation between the abundance of CTCF and gene expression, which could be explained by blockage of nucleosome deposition at those promoters. In summary, these results show evidence of conserved and divergent functions of gene regulators in vertebrates and set a precedent for studies of genome organization in zebrafish
Caron, Jérôme. "Hépatocytes différenciés à partir de cellules souches pluripotentes : un modèle d’études physiopathologiques et de thérapie génique et cellulaire - Application à l'hypercholestérolémie familiale de type IIA." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS533/document.
Liver metabolic diseases modeling and cell therapy approaches require a a reliable and well-characterized cell source. Due to their specific properties, pluripotent stem cells represent a credible alternative to primary human hepatocytes. Thus, we have defined a new approach to differentiate a European human embryonic stem cell line, generated in GMP-compatible conditions, into hepatocytes that are functional in vitro and in vivo after transplantation into a murine model of acute liver failure. We have then used induced pluripotent stem cells from a homozygous patient with a mutation leading to an absence of the low-density lipoproteins receptor (LDLR) to model familial hypercholesterolemia type IIA (FH) in vitro. As hepatocytes are the only cells able to metabolize cholesterol into bile acids, we have improved our approach to differentiate these iPSC into hepatocytes displaying cell functional organization and polarization. We have shown that our model reproduced FH physiopathology and have also restored, by the genetic targeted correction at the AAVS1 locus using CRISPR/Cas technology and subsequent hepatocyte differentiation, the LDLR expression – inducible by statins - and functionality. Moreover, we have demonstrated that the LDLR does not seem to be involved in hepatitis C virus entry or replication but rather in viral morphogenesis steps. This model will be useful to develop new cholesterol-lowering and antiviral drugs as well as new cell therapy options. Furthermore, it can be applied to similar studies for other liver metabolic disorders
Draiblate, Beatriz Lopes. "Correction of sickle-cell anemia using CRISPR-Cas9 system in hematopoietic stem cells." Master's thesis, 2020. http://hdl.handle.net/10451/46527.
Drepranocitosis (or sickle cell anemia - SCA) is a genetic hereditary disease that affects millions of people worldwide, bearing significant clinical features and a compromised prognosis with increased recurrences of crisis. Many treatments have been suggested to help dealing with sickle cell anemia, either by reducing and managing the consequences of the disease, or even by trying to solve it (bone marrow transplant). However, until date, there has not been developed a “perfect” therapeutic approach. Gene therapy has been used as the ultimate weapon to treat diseases whose cure cannot be achieved with traditional methods. CRISPR-Cas9 showed to be potentially safer and more efficient in treating SCD than other conventional gene therapies, which is presumed to be a result of the precision of the correction of this tool and the lack of use of viral vectors. Comparing with other available gene-editing techniques, namely zinc finger nucleases (ZFNs) and transcriptional activator-like effector nucleases (TALENs), CRISPR/Cas9 offers some advantages, as well as some limitations and complications. Overcoming these challenges and issues concerning the delivery of such tools to hematopoietic stem cells (HSCs) conserving their engrafting ability, may open the way to available curative approaches for SCD and other hemoglobinopathies
A drepanocitose (ou anemia falciforme) é uma doença genética hereditária que afeta milhões de pessoas em todo o mundo, sendo mais frequente em famílias com ascendência africana. Esta anemia é causada por uma mutação pontual no sexto codão da β-globina que leva à substituição de um ácido glutâmico por uma valina. Tal mutação é responsável pela alteração da forma da hemáciaepela alteração da hemoglobina. Consequentemente, esta torna-se menos solúvel em água e forma precipitados fibrosos, obtendo uma conformação de foice. Esta fragilidade faz com que as hemácias sofram lise com frequência na corrente sanguínea, diminuindo a sua concentração. A hemoglobina é uma proteína tetramétrica composta por dois pares de cadeias de globina, cada uma com o seu grupo heme. Hemácias normais de adultos possuem, maioritariamente, HbA (α2β2), juntamente com pequenas quantidades de HbA2(α2δ2) e hemoglobina fetal (HbF;α2γ2). Cerca de 2 milhões de indivíduos são heterozigóticos para HbS, constituindo uma condição assintomática. Indivíduos homozigóticos para HbS produzem sintomas da anemia falciforme. Nestes indivíduos, quase toda a hemoglobina é HbS. São as propriedades químico-fisiológicas anormais da hemoglobina (HbS –“sickle”) as responsáveis pela doença. A clínica desta patologia inclui crises anemia hemolítica, reticulócitos, e crises vaso-oclusivas, que podem levar a isquémia dos tecidos onde ocorrem. Um aumento do número de crises que necessitem de hospitalização estão associadas a um pior prognóstico e a uma redução da sobrevida, provavelmente devido a lesão crónica de órgãos. A anemia falciforme é endémica nalgumas áreas geográficas, nomeadamente na África Subsariana, devido à sua proteção relativa contra a malária. Anualmente, cerca de 300000 crianças nascem com esta patologia, com uma mortalidade entre 75-90% até aos 5 anos, principalmente devido a doenças infeciosas. É importante salientar que esta proteção relativa contra a malária apenas se verifica em indivíduos heterozigóticos (pois a falciformização das células facilita a sua remoção da circulação sanguínea pelos macrófagos), enquanto que indivíduos homozigóticos estão mais suscetíveis a consequências letais, por exemplo, pela exacerbação da anemia hemolítica e pela reduzida remoção de parasitas (consequência do hiposplenismo funcional). Os tratamentos para esta anemia, atualmente, incluem antibióticos (como a profilaxia com penicilina), vacinação contra Streptococcus pneumoniae, transplante de medula óssea, transfusões de sangue e alguns fármacos que auxiliam no controlo sintomático da doença. A hidroxiureia tem vindo a ser desenvolvida, a qual parece estimular a produção de hemoglobina fetal, prevenindo que as hemácias obtenham a forma de foice. Ao aumentar a concentração de hemoglobina fetal (HbF), que interfere com a formação de HbS, reduz a falciformização das hemácias. Além disso, reduz a inflamação crónica ao diminuir a contagem de neutrófilos. Atualmente, parece ser o melhor tratamento disponível para esta doença. As primeiras técnicas de edição genómica baseavam-se em sistema guiados por proteínas, como os Zinc Finger (ZFNs) e os TALENs (Transcription Activator-Like Effector nucleases). Estas nucleases contêm domínios específicos de ligação a sequências DNA alvo, ligados a um domínio de clivagem de DNA não-específico, o qual induz quebras duplas de cadeias na sequência alvo. As quebras duplas de cadeias são, então, reparadas através de mecanismos de reparação do DNA, estimulando, por exemplo, a recombinação homóloga entre um cromossoma “terapêutico” de DNA e o cromossoma alvo. Recentemente, um novo mecanismo de edição de genoma, o sistema CRISPR/Cas, emergiu como uma alternativa para o tratamento de desordens genéticas. Este sistema usa uma DNA endonuclease guiada por um RNA guia para induzir quebras duplas de cadeias, produzindo o mesmo efeito que as nucleases ZNFs e TALENs, mas possuindo outras vantagens. Ao ser um sistema guiado por RNA, torna-se mais fácil projetar devido à possibilidade de usar uma molécula de RNA complementar ao local preciso de edição genómica, guiando a clivagem. Esta técnica, assim, constitui uma alternativa mais rápida e eficiente que sistemas de edição de genomas guiados por proteínas. Os principais riscos associados às terapias de edição genómica associam-se à possibilidade de ocorrência de mutagénese, caso o gene terapêutico seja inserido noutra parte do genoma diferente do alvo, levando à disrupção do normal funcionamento da célula ao mutar outro gene wild-type. Outro problema associado é o risco de resposta imunes contra os vetores, principalmente se administrados in vivo. Durante décadas, doenças hematológicas como a talassémia e a anemia falciforme têm sido alvo de terapias de edição genómica. No entanto, devido à complexidade da regulação da expressão do gene da globina (devido ao splicing alternativo e à importância dos intrões na regulação deste gene), a utilização destas técnicas tem sido um desafio. Ensaios clínicos de terapia de edição genómica em células estaminais em doentes com talassémia mostraram resultados promissores, com uma correlação entre a eficácia clínica e a eficácia de transferência de genes. Neste trabalho, descrevem-se métodos e resultados alcançados em trabalhos que objetivaram corrigir a mutação causadora da anemia falciforme recorrendo à técnica de CRISPR-Cas9. Sumariamente, procedeu-se à construção de um plasmídeo que contivessea nuclease Cas9 e um RNA guia complementar ao intrão 2 do gene da β-globina HbSe à construção de um vetor dador (terapêutico) que transportava a sequência codificante wild-type do gene da β-globina HbS, flanqueada por dois braços de homologia que irão ter como alvo o intrão 2 do gene. De seguida, procedeu-se à avaliação da eficiência de corte. Após se proceder à cotransfeção para células progenitoras/estaminais hematopoiéticas CD34 + (HSPCs) destes vetores, procedeu-se à avaliação da eficiência desta abordagem, através de técnicas como genotipagem por PCR. Procedeu-se à diferenciação de HSPCs derivadas de pacientes com anemia falciforme em eritrócitos, seguindo-se testes para avaliar a falciformização, mostrando que estas células não eram tão sensíveis à hipoxia e que não adquiriam aforma de foice, contrastando com o controlo de células homozigóticas para HbS. Estes trabalhos mostraram que a utilização da técnica de CRISPR-Cas9 em HSPCs humanas possibilita a correção da mutação HbS (pelo menos num dos alelos), pelo que este método poderá ser utilizado como possível terapia para esta doença. Estudos que utilizaram modelos animais, nomeadamente ratinhos portadores da mutação HbS, mostraram que não só é possível realizara correção da mutação utilizando CRISPR-Cas9, como também que esta técnica parece ser potencialmente mais segura e eficiente comparando com outras técnicas de edição genómica, presumivelmente devido à precisão da correção e ao facto de não recorrer ao uso de vetores virais. Embora existam outras vantagens associadas a esta técnica(como a simplicidade e a facilidade de criação de gRNAs), várias são, também, as limitações que ainda hoje não se conseguiram ultrapassar (nomeadamente a ocorrência de eventos off-site, a baixa taxa de reparação de DNA pela via de reparação homóloga direta em células de mamíferos e a possibilidade de indução de β-talassémia). O futuro da utilização destas técnicas curativas para a anemia falciforme e outras hemoglobinopatias está dependente da capacidade de descobrir técnicas que nos permitam ultrapassar estes desafios e outros problemas relacionados com a entrega destas ferramentas às células hematopoiéticas. Globalmente, a incidência da anemia falciforme tem aumentado, com um foco importante em países como a Nigéria, a República Democrática do Congo e a Índia. Além de ter em conta o potencial que estes novos tratamentos oferecem aos pacientes, é igualmente importante ter noção do enquadramento geral. Nos locais onde a doença é mais prevalente (nomeadamente na África Subsariana), qualquer novo tratamento é praticamente inacessível. Estima-se que, para uma esperança media de vida de setenta anos para um doente com anemia falciforme, que o custo total associado à doença ronde os dez milhões de dólares. Com o aumento da sofisticação das técnicas utilizadas, há, também, um aumento do custo associado. Enquanto fármacos como a hidroxiureia acarretam um custo de aproximadamente 1000 dólares por ano (cerca de 70 000dólaresno total), o transplante de células estaminais e a terapia de edição genómica pode custar mais de 1 000 000 dólares. Embora se verifique uma diferença substancial de valores entre ambos os tratamentos, a terapia de edição genómica parece ser mais custo-efetiva, ao ser um tratamento único com potencial curativo.
Sürün, Duran. "High Efficiency Gene Correction in Hematopoietic Cells by Donor Template-free CRISPR/Cas9 Genome Editing." Phd thesis, 2018. https://tuprints.ulb.tu-darmstadt.de/7247/7/Dissertation_nach_Disputation.pdf.
Conceição, André Filipe Vieira da. "CRISPR-Cas9 as a tool for gene therapy in Machado-Joseph disease: silencing ATXN3 and CAG expansion correction." Master's thesis, 2019. http://hdl.handle.net/10316/87874.
Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3, is a neurodegenerative disorder considered to be the most common form of autosomal dominantly-inherited ataxia in the world. It is a rare disorder, although it has a significative prevalence in some regions of Portugal, especially in the archipelago of Azores. MJD symptoms include a loss of motor coordination and other neurological signs, with the cerebellum being the most affected brain region. MJD arises from an abnormal CAG trinucleotide expansion within the exon 10 of the human ATXN3 gene, which encodes for a protein named ataxin-3 (atxn-3), that bears an aberrant polyglutamine (polyQ) tract in the disease context. The exact biological function of atxn-3 is not fully understood, but it has been described that, when expanded atxn-3 undergoes a toxic gain-of-function that deregulates normal cellular pathways leading to neuronal loss. Recently, it has been suggested that abnormal CAG tracts in mRNA transcripts might also be toxic. As with other polyglutamine diseases, greater numbers of CAG repeats are associated with earlier ages of onset and more severe symptoms.Currently, no therapies capable of delaying or treating the disease are available, and MJD remains a fatal disorder. Many of the therapeutic strategies that have been tested act at a post-transcriptional level, being unable to prevent the putative toxicity of CAG expanded mRNA transcripts. Therefore, new strategies that act at a pre-transcriptional level may be advantageous.However, disease studies can only be robust and feasible when the adequate disease model is used. Yet, the available mouse models used to study MJD either fail to properly mimic the actual genetic context of the disease or are of limited use due to slow and mild symptom progression.In the last decade, the field of gene editing has been thriving. The use of the CRISPR/Cas9 system as a tool for gene editing brought the possibility of performing low-cost, flexible and easy genomic manipulation virtually at any loci. Moreover, CRISPR/Cas9 variants, such as the catalytic inactivated Cas9 (dCas9) have shown promising results regarding gene transcription regulation. In the first part of this work, we planned to establish an in vitro strategy to refine the yeast artificial chromosome (YAC) MJD-Q84.2 mouse, which is the MJD model that best recapitulates the symptoms and the genetic context of the human condition. In this work we proposed to use gene editing tools to overexpand the ATXN3 CAG tract in the exon 10, from 84 to 141 CAG; applying this strategy to the model would be expected to generate a robust mouse model that displayed a more severe phenotype and an earlier disease onset, comparing to the YAC MJD-Q84.2 model. However, the in vitro results here presented, using HEK 293T cells, showed that the strategy used was inefficient at overexpanding the CAG repeats.At the same time, a CRISPR/Cas9-based strategy for correcting the pathogenic ATXN3 gene that could be used to generate isogenic MJD patient-derived cell lines was also tested. The study here presented, using HEK 293T cells, showed that it is possible to integrate a DNA fragment containing 14 CAG repeats plus a selection cassette in the exon 10 of the ATXN3 gene. However, this strategy was not completely infallible, and integration seemed to be independent from Cas9 activity. In the second part of this work, we assessed the effects of dCas9-KRAB as a strategy to pre-transcriptionally silence mutant ATXN3 in a MJD mouse model. In vivo results showed that this approach has a therapeutic potential to improve motor performance in a severely-impaired transgenic mouse model of MJD.
A doença de Machado-Joseph (DMJ), também conhecida por ataxia espinocerebelosa tipo 3, é uma doença neurodegenerativa e a forma mais comum de ataxia hereditária dominante no mundo. É uma doença rara, porém tem uma prevalência significativa em algumas regiões de Portugal, nomeadamente no arquipélago dos Açores. Os sintomas de DMJ incluem perda de coordenação motora bem como outros sinais neurológicos, sendo o cerebelo a região do cérebro mais afetada. A DMJ surge de uma expansão anormal de trinucleótidos CAG no exão 10 do gene ATXN3, que codifica para a proteína ataxina-3 (atxn-3). No contexto da doença, a atxn-3 contém uma sequência de glutaminas (poliQ) anormalmente longa. As funções biológicas da proteína atxn-3 não são totalmente conhecidas, contudo tem sido descrito que a atxn-3 expandida adquire uma função tóxica que desregula o normal funcionamento de diversos sistemas celulares, levando à morte neuronal. Recentemente, tem sido sugerido que tratos CAG anormais presentes em transcritos de mRNA podem também ser tóxicos. Tal como em outras doenças de poliglutaminas, um maior número repetições CAG tem sido associado a sintomas mais severos, com um aparecimento mais precoce.Atualmente, não há terapias capazes de tratar ou atrasar o curso da doença, e, portanto, a DMJ continua a ser fatal. Algumas estratégias terapêuticas que têm sido testadas atuam ao nível pós-transcricional e são por isso incapazes de prevenir os putativos efeitos tóxicos dos transcritos de mRNA que contêm uma cadeia de CAGs expandida. Assim sendo, novas estratégias que atuem a um nível pré-transcricional podem vir a ser vantajosas.O estudo de doenças humanas apenas consegue ser robusto quando é usado um modelo de doença adequado. Porém, os modelos de murganho presentemente usados para estudar a DMJ ou não reproduzem de forma fiel o contexto genético da doença ou apresentam sintomas pouco acentuados e uma progressão lenta que limitam a sua utilização.Na última década, a área da edição genética tem tido desenvolvimentos extraordinários. O uso da CRISPR/Cas9 como uma ferramenta para edição genética trouxe a possibilidade de manipular o genoma virtualmente em qualquer locus, de uma forma barata, fácil e flexível. Além do mais, variantes da CRISPR/Cas9, como é o caso da Cas9 cataliticamente inativa (dCas9), têm mostrado resultados promissores no que diz respeito à regulação da transcrição genética.Na primeira parte deste trabalho pretendemos estabelecer uma estratégia in vitro para aperfeiçoar um modelo de DMJ em murganho designado por yeast artificial chromosome (YAC) MJD-Q84.2, que é considerado como o modelo que melhor recapitula os sintomas e o contexto genético humano em condições de doença. Neste trabalho, utilizámos ferramentas de edição genética para sobreexpandir o trato CAG do exão 10 do gene ATXN3, de 84 para 141 CAGs; ao aplicar esta estratégia ao modelo de murganho seria expectável que se criasse um modelo robusto, com um fenótipo mais severo e em que os sintomas se manifestassem mais cedo em comparação com o já existente modelo YAC MJD-Q84.2. Contudo, os resultados in vitro descritos neste trabalho mostraram que a estratégia usada parece ser ineficiente na sobreexpansão das repetições CAG em células HEK 293T.Paralelamente, usando também a CRISPR/Cas9, foi testada uma estratégia para corrigir o gene ATXN3 mutante, que pudesse ser usada para criar linhas celulares isogénicas derivadas de pacientes de DMJ. O estudo aqui apresentado, usando células HEK 293T, mostrou ser possível integrar um fragmento de DNA contendo 14 repetições do trinucleótido CAG e uma cassete de seleção no exão 10 do gene ATXN3. Contudo, esta abordagem não se mostrou totalmente fiável e que foi detetada integração independente da atividade da Cas9.Na segunda parte deste trabalho foram avaliados os efeitos da dCas9-KRAB como estratégia de silenciamento a nível pré-transcricional do gene humano da ATXN3 num modelo animal de DMJ. Os resultados in vivos mostraram que esta abordagem tem potencial terapêutico, melhorando a performance motora num modelo DJM transgénico severamente afetado.
Outro - This work was funded by the ERDF through the Regional Operational Program Center 2020, Competitiveness Factors Operational Program (COMPETE 2020) and National Funds through FCT (Foundation for Science and Technology) - BrainHealth2020 projects (CENTRO-01-0145-FEDER-000008), ViraVector (CENTRO-01-0145-FEDER-022095), CortaCAGs (PTDC/NEU-NMC/0084/2014|POCI-01-0145-FEDER-016719), SpreadSilencing (POCI-01-0145-FEDER-029716, POCI-01-0145-FEDER-032309) as well as SynSpread, ESMI and ModelPolyQ under the EU Joint Program - Neurodegenerative Disease Research (JPND), the last two co-funded by the European Union H2020 program, GA No.643417; by the National Ataxia Foundation (USA), the American Portuguese Biomedical Research Fund (APBRF) and the Richard Chin and Lily Lock Machado-Joseph Disease Research Fund.
Ousterout, David Gerard. "Genetic Correction of Duchenne Muscular Dystrophy using Engineered Nucleases." Diss., 2014. http://hdl.handle.net/10161/8769.
Duchenne muscular dystrophy (DMD) is a severe hereditary disorder caused by a loss of dystrophin, an essential musculoskeletal protein. Decades of promising research have yielded only modest gains in survival and quality of life for these patients and there have been no approved gene therapies for DMD to date. There are two significant hurdles to creating effective gene therapies for DMD; it is difficult to deliver a replacement dystrophin gene due to its large size and current strategies to restore the native dystrophin gene likely require life-long administration of a gene-modifying drug. This thesis presents a novel method to address these challenges through restoring dystrophin expression by genetically correcting the native dystrophin gene using engineered nucleases that target one or more exons in a mutational hotspot in exons 45-55 of the dystrophin gene. Importantly, this hotspot mutational region collectively represents approximately 62% of all DMD mutations. In this work, we utilize various engineered nuclease platforms to create genetic modifications that can correct a variety of DMD patient mutations.
Initially, we demonstrate that genome editing can efficiently correct the dystrophin reading frame and restore protein expression by introducing micro-frameshifts in exon 51, which is adjacent to a hotspot mutational region in the dystrophin gene. Transcription activator-like effector nucleases (TALENs) were engineered to mediate highly efficient gene editing after introducing a single TALEN pair targeted to exon 51 of the dystrophin gene. This led to restoration of dystrophin protein expression in cells from DMD patients, including skeletal myoblasts and dermal fibroblasts that were reprogrammed to the myogenic lineage by MyoD. We show that our engineered TALENs have minimal cytotoxicity and exome sequencing of cells with targeted modifications of the dystrophin locus showed no TALEN-mediated off-target changes to the protein coding regions of the genome, as predicted by in silico target site analysis.
In an alternative approach, we capitalized on the recent advances in genome editing to generate permanent exclusion of exons by using zinc-finger nucleases (ZFNs) to selectively remove sequences important in specific exon recognition. This strategy has the advantage of creating predictable frame restoration and protein expression, although it relies on simultaneous nuclease activity to generate genomic deletions. ZFNs were designed to remove essential splicing sequences in exon 51 of the dystrophin gene and thereby exclude exon 51 from the resulting dystrophin transcript, a method that can potentially restore the dystrophin reading frame in up to 13% of DMD patients. Nucleases were assembled by extended modular assembly and context-dependent assembly methods and screened for activity in human cells. Selected ZFNs had moderate observable cytotoxicity and one ZFN showed off-target activity at two chromosomal loci. Two active ZFN pairs flanking the exon 51 splice acceptor site were transfected into DMD patient cells and a clonal population was isolated with this region deleted from the genome. Deletion of the genomic sequence containing the splice acceptor resulted in the loss of exon 51 from the dystrophin mRNA transcript and restoration of dystrophin expression in vitro. Furthermore, transplantation of corrected cells into the hind limb of immunodeficient mice resulted in efficient human dystrophin expression localized to the sarcolemma.
Finally, we exploited the increased versatility, efficiency, and multiplexing capabilities of the CRISPR/Cas9 system to enable a variety of otherwise challenging gene correction strategies for DMD. Single or multiplexed sgRNAs were designed to restore the dystrophin reading frame by targeting the mutational hotspot at exons 45-55 and introducing either intraexonic small insertions and deletions, or large deletions of one or more exons. Significantly, we generated a large deletion of 336 kb across the entire exon 45-55 region that is applicable to correction of approximately 62% of DMD patient mutations. We show that, for selected sgRNAs, CRISPR/Cas9 gene editing displays minimal cytotoxicity and limited aberrant mutagenesis at off-target chromosomal loci. Following treatment with Cas9 nuclease and one or more sgRNAs, dystrophin expression was restored in Duchenne patient muscle cells in vitro. Human dystrophin was detected in vivo following transplantation of genetically corrected patient cells into immunodeficient mice.
In summary, the objective of this work was to develop methods to genetically correct the native dystrophin as a potential therapy for DMD. These studies integrate the rapid advances in gene editing technologies to create targeted frameshifts that restore the dystrophin gene around patient mutations in non-essential coding regions. Collectively, this thesis presents several gene editing methods that can correct patient mutations by modification of specific exons or by deletion of one or more exons that results in restoration of the dystrophin reading frame. Importantly, the gene correction methods described here are compatible with leading cell-based therapies and in vivo gene delivery strategies for DMD, providing an avenue towards a cure for this devastating disease.
Dissertation
Tremblay-Laganière, Camille. "Thérapie génique ciblant CD33 dans les cellules souches hématopoïétiques, une approche innovatrice pour le traitement de la leucémie myéloïde aiguë." Thèse, 2018. http://hdl.handle.net/1866/22328.