Browsing by Author "King, Justin S."

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    Author Correction: Massively parallel in vivo CRISPR screening identifies RNF20/40 as epigenetic regulators of cardiomyocyte maturation
    (Springer Nature, 2021-08-19) VanDusen, Nathan J.; Lee, Julianna Y.; Gu, Weiliang; Butler, Catalina E.; Sethi, Isha; Zheng, Yanjiang; King, Justin S.; Zhou, Pingzhu; Suo, Shengbao; Guo, Yuxuan; Ma, Qing; Yuan, Guo-Cheng; Pu, William T.; Medical and Molecular Genetics, School of Medicine
    Correction to: Nature Communications 10.1038/s41467-021-24743-z, published online 21 July 2021. The original version of this Article contained an error in the spelling of the author William T. Pu, which was incorrectly given as William William Pu. This has now been corrected in both the PDF and HTML versions of the Article.
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    Cardiac Applications of CRISPR/AAV-Mediated Precise Genome Editing
    (bioRxiv, 2024-12-04) Zheng, Yanjiang; Mayourian, Joshua; King, Justin S.; Li, Yifei; Bezzerides, Vassilios J.; Pu, William T.; VanDusen, Nathan J.; Pediatrics, School of Medicine
    The ability to efficiently make precise genome edits in somatic tissues will have profound implications for gene therapy and basic science. CRISPR/Cas9 mediated homology-directed repair (HDR) is one approach that is commonly used to achieve precise and efficient editing in cultured cells. Previously, we developed a platform capable of delivering CRISPR/Cas9 gRNAs and donor templates via adeno-associated virus to induce HDR (CASAAV-HDR). We demonstrated that CASAAV-HDR is capable of creating precise genome edits in vivo within mouse cardiomyocytes at the neonatal and adult stages. Here, we report several applications of CASAAV-HDR in cardiomyocytes. First, we show the utility of CASAAV-HDR for disease modeling applications by using CASAAV-HDR to create and precisely tag two pathological variants of the titin gene observed in cardiomyopathy patients. We used this approach to monitor the cellular localization of the variants, resulting in mechanistic insights into their pathological functions. Next, we utilized CASAAV-HDR to create another mutation associated with human cardiomyopathy, arginine 14 deletion (R14Del) within the N-terminus of Phospholamban (PLN). We assessed the localization of PLN-R14Del and quantified cardiomyocyte phenotypes associated with cardiomyopathy, including cell morphology, activation of PLN via phosphorylation, and calcium handling. After demonstrating CASAAV-HDR utility for disease modeling we next tested its utility for functional genomics, by targeted genomic insertion of a library of enhancers for a massively parallel reporter assay (MPRA). We show that MPRAs with genomically integrated enhancers are feasible, and can yield superior assay sensitivity compared to tests of the same enhancers in an AAV/episomal context. Collectively, our study showcases multiple applications for in vivo precise editing of cardiomyocyte genomes via CASAAV-HDR.
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    Efficient In Vivo Homology-Directed Repair Within Cardiomyocytes
    (American Heart Association, 2022) Zheng, Yanjiang; VanDusen, Nathan J.; Butler, Catalina E.; Ma, Qing; King, Justin S.; Pu, William T.; Pediatrics, School of Medicine
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    Massively parallel in vivo CRISPR screening identifies RNF20/40 as epigenetic regulators of cardiomyocyte maturation
    (Springer Nature, 2021-07-21) VanDusen, Nathan J.; Lee, Julianna Y.; Gu, Weiliang; Butler, Catalina E.; Sethi, Isha; Zheng, Yanjiang; King, Justin S.; Zhou, Pingzhu; Suo, Shengbao; Guo, Yuxuan; Ma, Qing; Yuan, Guo-Cheng; Pu, William T.; Medical and Molecular Genetics, School of Medicine
    The forward genetic screen is a powerful, unbiased method to gain insights into biological processes, yet this approach has infrequently been used in vivo in mammals because of high resource demands. Here, we use in vivo somatic Cas9 mutagenesis to perform an in vivo forward genetic screen in mice to identify regulators of cardiomyocyte (CM) maturation, the coordinated changes in phenotype and gene expression that occur in neonatal CMs. We discover and validate a number of transcriptional regulators of this process. Among these are RNF20 and RNF40, which form a complex that monoubiquitinates H2B on lysine 120. Mechanistic studies indicate that this epigenetic mark controls dynamic changes in gene expression required for CM maturation. These insights into CM maturation will inform efforts in cardiac regenerative medicine. More broadly, our approach will enable unbiased forward genetics across mammalian organ systems.