Journal: Molecular Therapy. Nucleic Acids

Article Title: Potential effects of endogenous RNA/DNA hybrids on CRISPR-Cas9-mediated homology-directed repair

doi: 10.1016/j.omtn.2026.102880

Figure Lengend Snippet: Modulation of HDR efficiency by R-loop resolution, cell-cycle perturbation, and locus context (A) ddPCR quantification of HDR events in HEPA1-6/SpCas9 cells transiently overexpressing human RNase H1 and transduced with 10,000 vg/cell of scAAVDJ-sgMid Alb + 10,000 vg/cell ssAAVDJ-donor Mid Alb, or 10,000 vg/cell of scAAVDJ-sg3′ Alb + 10,000 vg/cell ssAAVDJ-donor 3′ Alb. (B) Schematic representation of cell cycle profiles in HEPA1-6 cells and murine hepatocytes. (C) Flow cytometry analysis of HEPA1-6/SpCas9 cells treated for 24 h with rapamycin (1 μM, 5 μM) or palbociclib (PD; 5 μM, 10 μM). DMSO-treated cells served as controls. (D) DRIP-qPCR analysis of HEPA1-6/SpCas9 cells after 24 h treatment with 5 μM rapamycin; DMSO-treated cells served as controls. (E) ddPCR detection of HDR events in HEPA1-6/SpCas9 cells pre-treated with 5 μM rapamycin for 24 h, followed by 72 h transduction with 10,000 vg/cell of scAAVDJ-sgMid Alb + 10,000 vg/cell ssAAVDJ-donor Mid Alb, or scAAVDJ-sg3′ Alb + ssAAVDJ-donor 3′ Alb. (F) IGV visualization of the Alb and Actb loci showing gRNA (sgActb) and donor (donor Actb) design targeting the 5′ region of Actb . (G) ddPCR detection of HDR events in HEPA1-6/SpCas9 cells transduced for 72 h with 10,000 vg/cell of scAAVDJ-sgActb + 10,000 vg/cell ssAAVDJ-donor Actb. Scrambled gRNA with donor served as negative control. (H) ddPCR detection of HDR events in HEPA1-6/SpCas9 cells pre-treated with 5 μM rapamycin for 24 h, followed by 72 h transduction with scAAVDJ-sgActb + ssAAVDJ-donor Actb. (I) ddPCR detection of HDR events in HEPA1-6/SpCas9 cells transiently overexpressing human RNase H1 and transduced with scAAVDJ-sgActb + ssAAVDJ-donor Actb. (J) DRIP-qPCR analysis of CD4 + T cells from a healthy donor, pre- and post-activation with 10 μg/mL PHA, 50 IU/mL IL-2, 5 ng/mL IL-7, and 5 ng/mL IL-15. DRIP, immunoprecipitated samples treated with S9.6 antibody which are enriched in R loops; RNAseH + , samples treated with RNAseH1+S9.9 antibody which are depleted of R-loops. (K) Table summarizing the effects of R-loops levels on indels, HDR, and AAV integration. N/A, not affected; ↑ increase; ↓ = decrease. Statistical analysis: (A and E) multiple t test; (C) two-way ANOVA with Dunnett’s post hoc test; (G–I) Student’s t test. p < 0.05, ∗ p < 0.01, ∗∗ p < 0.001, ∗∗∗ p < 0.0001. Error bars represent mean ± SD.

Article Snippet: HEPA1-6/SpCas9 cells were treated with rapamycin (Selleck, S1039) or palbociclib (Selleck, S1116) for 24 h, fixed in 70% ethanol, stained with propidium iodide, and analyzed by flow cytometry (NovoCyte Penteon, Agilent).

Techniques: Transduction, Flow Cytometry, Negative Control, Activation Assay, Immunoprecipitation