Project description:Based on the hypothesis that, enhancing the local concentration of donor oligos could increase the correction rates, we generated and tested novel CRISPR-Cas9 systems, in which the DNA repair template is covalently conjugated to Cas9 (RNPD system). To validate our results from the HEK293T reporter cells, we here tested our approach at different endogenous genomic loci and in different cell types. We first targeted the human beta globin (HBB) locus in the K562 cell line, and analyzed correction- and editing frequencies using next generation sequencing (NGS). Next we targeted the Rosa26 and proprotein convertase subtilisin/kexin type 9 (Pcsk9) locus in mouse embryonic stem cells (mESCs). Here, RNPD system was always compared to Cas9 SNAP-tag fusion proteins with uncoupled donor oligos. To also directly compare the engineered RNPD system to the classical CRISPR-Cas9 system, we performed experiments where we used wild-type Cas9 with the uncoupled donor oligos as a control. We therefore targeted the fluorescent reporter locus as well as the endogenous loci HBB, empty spiracles homeobox 1 (EMX1), and C-X-C chemokine receptor type 4 (CXCR4) in HEK293T cells. Finally, we performed the analysis of three computationally predicted off-target sites of the reporter locus.
Project description:Reticular Dysgenesis (RD) is a rare but devastating form of severe combined immunodeficiency, characterized by a maturation arrest of the myeloid and lymphoid lineages paired with sensorineural hearing loss. RD is caused by biallelic loss-of-function mutations in the mitochondrial enzyme adenylate kinase 2 (AK2). To study the effect of AK2 depletion on HSPC differentiation, we developed a biallelic AK2 CRISPR knock-out model using human HSPCs. AK2 depleted HSPCs display severe proliferation and myeloid differentiation defects, recapitulating RD patient phenotype.
Project description:We developed a technique for generating hypothalamic neurons from human pluripotent stem cells. Here, as proof-of-principle, we examine the use of these cells in modeling of a monogenic form of severe obesity: PCSK1 deficiency. We generated PCSK1 (PC1/3)-deficient human embryonic stem cell (hESC) lines using both shRNA and CRISPR-Cas9, and investigated pro-opiomelanocortin (POMC) processing using hESC-differentiated hypothalamic neurons.
Project description:Human acute myeloid leukemia cell lines OCI-AML2 and OCI-AML3 were used in a CRISPR/Cas9-mediated approach to specifically target DDX3X’s gene sequences encoding the RNA binding domain of the helicase. DDX3X RNA binding domain is bipartite in the two halves of the helicase core. sgRNAs were designed to target both halves of the domain (named RNA binding domain A and B – RBDA and RBDB). We performed RNA-seq to observe the gene expression changes in both OCI-AML2 and OCI-AML3 cell lines following the not-combined CRISPR/Cas9 –mediated targeting of both regions of the DDX3X RNA binding domain. Control CRISPR/Cas9 performed with no sgRNA expressing vector (named “empty vector”) was performed in both cell lines. The latter condition was used as a control for gene expression changes analysis, for each cell line.
Project description:Primary Hyperoxaluria Type 1 (PH1) is a rare inherited metabolic disorder characterized by oxalate overproduction in the liver, resulting in renal damage. It is caused by mutations in the AGXT gene. Combined liver and kidney transplantation is currently the only permanent curative treatment. We combined locus-specific gene correction and hepatic direct cell reprogramming to generate autologous healthy induced hepatocytes (iHeps) from PH1 patient-derived fibroblasts. First, site-specific AGXT corrected cells were obtained by homology directed repair (HDR) assisted by CRISPR/Cas9, following two different strategies: accurate point mutation (c.853T>C) correction or knock-in of an enhanced version of AGXT cDNA. Then, iHeps were generated, by overexpression of hepatic transcription factors. Generated AGXT-corrected iHeps showed hepatic gene expression profile and exhibited in vitro reversion of oxalate accumulation compared to non-edited PH1-derived iHeps. This strategy set up a potential alternative cellular source for liver cell replacement therapy and a personalized PH1 in vitro disease model.
Project description:The molecular basis of stromal immunomodulation is still unresolved. Here, we show a novel function for dedicator of cytokinesis 2 (DOCK2) in regulating extra-hematopoietic immune function of three independent stromal cell sources: induced pluripotent stem cells (iPSC)-derived mesodermal stromal cell (iPS-MSC), severe combined immunodeficiency (SCID) patient-derived fibroblasts and CRISPR/Cas9 knockout cells (iPS-MSCDOCK2KO). We first reprogrammed human mesenchymal stromal cells (MSC) into iPSC before differentiating the iPSCs back into MSC. Immature iPS-MSCs lacked immunosuppressive potential. Successive phenotypic maturation facilitated immunomodulatory function, while maintaining clonogenicity, comparable to parental MSCs. Sequential RNA-seq displayed time-dependent immune-related gene expression eventually resembling parental MSCs. SCID patient-derived fibroblasts harboring bi-allelic DOCK2 mutations also showed significantly reduced immunomodulatory capacity compared to non-mutated fibroblasts. CRISPR/Cas9-mediated DOCK2 knockout in healthy iPSCs resulted in significantly reduced immunomodulatory capacity, reduced F-actin stress-fibers, and a disturbed subcellular localization of CDC42 activation. We provide first evidence for extra-hematopoietic immunomodulation by the guanin exchange factor DOCK2. This suggests that persisting immune disease after successful blood stem cell transplantation in SCID patients could in part be due to loss-of-function DOCK2 mutations.
Project description:The molecular basis of stromal immunomodulation is still unresolved. Here, we show a novel function for dedicator of cytokinesis 2 (DOCK2) in regulating extra-hematopoietic immune function of three independent stromal cell sources: induced pluripotent stem cells (iPSC)-derived mesodermal stromal cell (iPS-MSC), severe combined immunodeficiency (SCID) patient-derived fibroblasts and CRISPR/Cas9 knockout cells (iPS-MSCDOCK2KO). We first reprogrammed human mesenchymal stromal cells (MSC) into iPSC before differentiating the iPSCs back into MSC. Immature iPS-MSCs lacked immunosuppressive potential. Successive phenotypic maturation facilitated immunomodulatory function, while maintaining clonogenicity, comparable to parental MSCs. Sequential RNA-seq displayed time-dependent immune-related gene expression eventually resembling parental MSCs. SCID patient-derived fibroblasts harboring bi-allelic DOCK2 mutations also showed significantly reduced immunomodulatory capacity compared to non-mutated fibroblasts. CRISPR/Cas9-mediated DOCK2 knockout in healthy iPSCs resulted in significantly reduced immunomodulatory capacity, reduced F-actin stress-fibers, and a disturbed subcellular localization of CDC42 activation. We provide first evidence for extra-hematopoietic immunomodulation by the guanin exchange factor DOCK2. This suggests that persisting immune disease after successful blood stem cell transplantation in SCID patients could in part be due to loss-of-function DOCK2 mutations.