Project description:The gain-of-function mutation of c.G6055A (p.G2019S) in Leucine-rich repeat kinase 2 (LRRK2) gene is the most prevalent genetic cause of Parkinson’s disease (PD). Although clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-based genome editing has been used to generate isogenic control lines, there are risks of creating indels and genomic instability together with a lower efficiency in non-dividing cells. The recent advance of adenine base editors (ABEs) could convert targeted A•T base pairs to G•C base pairs without double-strand DNA breaks or donor DNA templates and function in post-mitotic cells. Here, we demonstrate a complete correction of an induced pluripotent stem cell (iPSC) line derived from a PD patient having LRRK2 p.G2019S mutation using variable genome editing methods, including CRISPR/Cas9-based homology-directed repair (HDR) and ABEs. The corrected isogenic iPSCs derived dopaminergic neurons showed a down-regulated LRRK2 kinase activity, decreased phospho-a-synuclein accumulations, reduced apoptosis and restored neurite shrinkage phenotypes. The mutation correction efficacy, off-target and indels rates between CRISPR/Cas9-HDR and ABE were compared. Among the 47 clones generated by HDR, 3 clones (6.4%) were on-targeted corrected, while ABE showed a much higher correction rate (13 of 53 clones, 24.5%). Whole genome sequencing analysis revealed that there are 27 clones of HDR (57.4%) having deletions but none in clones of ABE, albeit ABE created 14 clones (26.4%) having off-target missense mutations. RNA sequencing and proteomic analysis of the mutant line identified 2220 differentially expressed genes compared with its isogenic control. Enrichment analysis demonstrated an over-representation of PD relevant pathways, including calcium ion dependent exocytosis, synaptic transports well as potential novel targets relevant to PD pathophysiology. These results envision that ABE could directly correct the pathogenic PD mutation in iPSCs for exploring the earliest events in PD pathophysiology and providing dopaminergic neurons for future cell therapies.
Project description:Donated human MII oocytes and zygotes were injected with ABE mRNA or RNP, or Cas9 RNP targeting indicated genes. The purpose of the experiment is to study DNA repair after base editing in preimplantation human embryos. Key findings are a lack of chromosomal aneuploidies in base editing samples, contrasting with the outcomes after Cas9 cleavage at the same sites. Off target base editing is highly gRNA dependent. Base editing is efficient, and lacks the genotoxicity of Cas9.
2026-06-19 | GSE290961 | GEO
Project description:Amplicon sequencing of base editing
Project description:To identify mutations that occurred in the nuclear and mitochondrial DNA of the yeast subjected to mtDNA base editing or Mito-BE screen, we performed whole-genome sequencing of cultured yeast cells after isolation of mitochondrial DNA.
Project description:Background: RNA editing encompasses a post-transcriptional process in which the genomically templated sequence is enzymatically altered and introduces a modified base into the edited transcript. Mammalian C-to-U RNA editing represents a distinct subtype of base modification, whose prototype is intestinal apolipoproteinB (apoB) mRNA, mediated by the catalytic deaminase Apobec-1. However, the genome-wide identification, tissue-specificity and functional implications of Apobec-1 mediated C-to-U RNA editing remains incomplete. Results: Deep sequencing, data filtering and Sanger-sequence validation of intestinal and hepatic RNA from wild-type and Apobec-1 deficient mice revealed 56 novel editing sites in 54 intestinal mRNAs and 22 novel sites in 17 liver mRNAs (74-81% Sanger sequenced validated), all within 3’ untranslated regions. Eleven of 17 liver RNAs shared editing sites with intestinal RNAs, while 6 sites were unique to liver. Changes in RNA editing led to corresponding changes in intestinal mRNA and protein levels in 11 genes. RNA editing in vivo following tissue-specific Apobec-1 adenoviral or transgenic Apobec-1 overexpression revealed that a subset of targets identified in wild-type mice were restored in Apobec-1 deficient mouse intestine and liver following Apobec-1 rescue. We found distinctive polysome profiles for several RNA editing targets and demonstrated novel exonic editing sites in nuclear preparations from intestine (but not hepatic) apoB RNA. RNA editing was validated using cell-free extracts from wild-type but not Apobec-1 deficient mice, demonstrating that Apobec-1 is required. Conclusions: These studies define selective, tissue-specific targets of Apobec-1 dependent RNA editing and show the functional consequences of editing are both transcript- and tissue-specific.