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Laverty, D. J.

Publications and source records attributed to Laverty, D. J..

4 recordsLinked to original sources

Integrative Multiomic Analysis Reveals How Non-Viral Delivery System Selection Shapes CRISPR Gene Editing Outcomes in Stem Cells.

The clinical translation of CRISPR gene editing is challenged by the lack of delivery systems that are both safe and efficient in therapeutically relevant cell types such as mesenchymal stem cells (MSCs). Non-viral delivery avoids the immunogenicity and genomic integration risks of viral vectors but faces fundamental trade-offs between editing efficiency and cytotoxicity. Here, we present a comprehensive multiomic analysis of four non-viral CRISPR delivery modalities including cell-penetrating peptide- (CPP), lipid-, and polymer-based nanoparticles and electroporation; across mRNA and ribonucleoprotein (RNP) molecular formats. We systematically evaluate each modality, demonstrating that lipid-based delivery achieved the highest editing rates at the cost of genomic instability risks, interferon pathway activation, and a pro-inflammatory shift in MSC paracrine activity. Alternatively, CPPs yield moderate editing rates while reducing these unintended side-effects, whereas polymers and electroporation consistently yielded the lowest efficiencies. CRISPR molecular format and delivery method interacted in a stress-dependent manner, with RNP delivery reducing editing rates under high-stress systems while improving them in lower-stress modalities such as CPP and electroporation. These findings establish that editing efficiency alone is an insufficient metric for delivery system selection, and that genomic stability, transcriptomic dysregulation, and inflammatory response must be treated as primary design criteria for CRISPR therapies.

bioengineering↗

MSIanalyzer: Targeted Nanopore Sequencing Enables Single Nucleotide Resolution Analysis of Microsatellite Instability Diversity

We present a targeted sequencing-based pipeline that profiles microsatellite instability (MSI) at single-nucleotide resolution. Targeted amplicons from the five widely studied Bethesda panel microsatellite loci were sequenced using Oxford Nanopore Technology in two microsatellite unstable colorectal cancer cell lines (HCT15, HCT116), two microsatellite stable cancer cell lines (TK6, U2OS), and two peripheral blood mononuclear cell samples from healthy donors. An anchor-extension algorithm was developed to capture repeat motifs while allowing interruptions, using a threshold informed by platform-specific error. Cluster-aware Dirichlet-multinomial and beta-binomial tests were applied for between-sample comparisons while accounting for read-level clustering within samples. The algorithm revealed distinct repeat profiles in HCT15 and HCT116 compared to other cell types and uncovered allelic diversity across samples at different MSI loci. Our approach complements existing short tandem repeat callers by preserving read-level diversity and delivering targeted, quantitative MSI calls with potential applications in mechanistic research and clinical assay development.

molecular biology↗

D-type cyclins regulate DNA mismatch repair in the G1 and S phases of the cell cycle, maintaining genome stability

The large majority of oxidative DNA lesions occurring in the G1 phase of the cell cycle are repaired by base excision repair (BER) rather than mismatch repair (MMR) to avoid long resections that can lead to genomic instability and cell death. However, the molecular mechanisms dictating pathway choice between MMR and BER have remained unknown. Here, we show that, during G1, D-type cyclins are recruited to sites of oxidative DNA damage in a PCNA- and p21-dependent manner. D-type cyclins shield p21 from its two ubiquitin ligases CRL1SKP2 and CRL4CDT2 in a CDK4/6-independent manner. In turn, p21 competes through its PCNA-interacting protein degron with MMR components for their binding to PCNA. This inhibits MMR while not affecting BER. At the G1/S transition, the CRL4AMBRA1-dependent degradation of D-type cyclins renders p21 susceptible to proteolysis. These timely degradation events allow the proper binding of MMR proteins to PCNA, enabling the repair of DNA replication errors. Persistent expression of cyclin D1 during S-phase increases the mutational burden and promotes microsatellite instability. Thus, the expression of D-type cyclins inhibits MMR in G1, whereas their degradation is necessary for proper MMR function in S. One-Sentence SummaryTo maintain genome stability, D-type cyclins limit mismatch repair (MMR) in G1, whereas their degradation is necessary for proper MMR function in S phase.

cell biology↗

ATM phosphorylates the FATC domain of DNA-PKcs at threonine 4102 to promote non-homologous end joining

Ataxia-telangiectasia mutated (ATM) drives the DNA damage response via modulation of multiple signal transduction and DNA repair pathways. Previously, ATM activity was implicated in promoting the non-homologous end joining (NHEJ) pathway to repair a subset of DNA double strand breaks (DSBs), but how ATM performs this function is still unclear. In this study, we identified that ATM phosphorylates the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a core NHEJ factor, at its extreme C-terminus at threonine 4102 (T4102) in response to DSBs. Phosphorylation at T4102 stabilizes the interaction between DNA-PKcs and the Ku-DNA complex and promotes assembly and stabilization of the NHEJ machinery at DSBs. Ablating phosphorylation at this site results in decreased NHEJ, radiosensitivity, and increased radiation-induced genomic instability. Collectively, these findings establish a key role for ATM in NHEJ-dependent repair of DSBs through positive regulation of DNA-PKcs.

molecular biology↗