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 therapeutic use of adeno-associated viral vector (AAV)-mediated gene disruption using CRISPR-Cas9 is limited by potential off-target modifications and the risk of uncontrolled integration of vector genomes into CRISPR-mediated double-strand breaks. To address these concerns, we explored the use of AAV-delivered paired Staphylococcus aureus nickases (D10ASaCas9) to target the Hao1 gene for the treatment of primary hyperoxaluria type 1 (PH1). Our study demonstrated effective Hao1 gene disruption, a significant decrease in glycolate oxidase expression, and a therapeutic effect in PH1 mice. The assessment of undesired genetic modifications through CIRCLE-seq and CAST-Seq analyses revealed neither off-target activity nor chromosomal translocations. Importantly, the use of paired-D10ASaCas9 resulted in a significant reduction in AAV integration at the target site compared to SaCas9 nuclease. Additionally, our study highlights the limitations of current analytical tools in characterizing modifications introduced by paired D10ASaCas9, necessitating the development of a custom pipeline for more accurate characterization. These results describe a positive advance towards a safe and effective potential long-term treatment for PH1 patients.
Project description:This study aims to investigate a wheat recombination hotspot (H1) in comparison with a “regular” recombination site (Rec7) on the sequence and epigenetic level in conditions with functional and non-functional Ph1 locus.
Project description:The targeting range of CRISPR-Cas9 base editors (BEs) is limited by their G/C-rich PAM sequences. To overcome this limitation, we developed a CRISPR/Cpf1-based BE by fusing the rat cytosine deaminase APOBEC1 to a catalytically inactive version of Lachnospiraceae bacterium Cpf1. The base editor recognizes a T-rich PAM sequence and converts C to T in human cells with low levels of indels, non-C-to-T substitutions and off-target editing.
Project description:C-to-T base editing mediated by CRISPR/Cas9 base editors (BEs) needs a G/C-rich PAM and the editing fidelity is compromised by unwanted indels and non-C-to-T substitutions. We developed CRISPR/Cpf1-based BEs to recognize a T-rich PAM and induce efficient C-to-T editing with few indels and/or non-C-to-T substitutions. The requirement of editing fidelity in therapeutic-related trials necessitates the development of CRISPR/Cpf1-based BEs, which also facilitates base editing in A/T-rich regions.
Project description:Primary hyperoxaluria type I (PH1) is a genetic disease caused by a deficiency in the peroxisomal alanine:glyoxylate aminotransferase (AGT) activity. Mutations in AGT mostly cause protein mistargeting and enhanced aggregation, although the molecular and structural basis of these mechanisms are unknown. In this work, we use hydrogen-deuterium exchange monitored by mass spectrometry (HDX-MS) to provide novel insight into these pathogenic mechanisms. We characterize the wild-type (WT) protein, the LM variant (containing the mutations P11L and I340M, a haplotype more frequent in PH1 patients) and the LM G170R (the most common genotype in PH1, introducing the G170R mutation on the LM background). Our study provides the first experimental analysis of the local stability and dynamics of AGT, showing that stability is heterogeneous in the native state and providing a blueprint for frustrated regions with potentially functional relevance. The LM and LM G170R variants destabilize locally the structure. Enzymatic transamination of the PLP bound to AGT hardly affects stability. Our study thus supports that AGT misfolding is not caused by dramatic effects on the stability and dynamics of the holo-protein.
Project description:To investigate the function of All0854, we constructed the all0854 deletion mutant Mall0854, in which all0854 was knocked out by CRISPER-cpf1. We then performed gene expression profiling analysis using data obtained from RNA-seq of wide type Nostoc sp. PCC 7120 and Mall0854.