Browsing by keyword "disease models"
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Integrated Multi-omics Characterization of Human Disease ModelsAnimal and cell-based models of human disease offer simplified biological systems for studying the basis of more complex pathologies under well-controlled conditions. An ever-expanding suite of genomic and transcriptomic tools allows us to thoroughly characterize these models, highlighting disease-driving molecular features and exposing novel therapeutic targets. Here, we integrate diverse DNA- and RNA-sequencing strategies to describe the gene-regulatory chromatin landscape of models for hepatoblastoma and retrovirally-infected CD4+ T-cells. We first developed a conditional hepatoblastoma mouse model using doxycycline-inducible YAP1 overexpression and constitutive β-cateninDelN90. We found that YAP1 withdrawal alone is sufficient to trigger tumor regression and substantially increase survival. We reasoned that a thorough chromatin profile of this tumor model during YAP1 withdrawal could reveal YAP1-driven mechanisms of hepatoblastoma tumorigenesis. Our integrated approach revealed 31 novel YAP1-targeted cis-regulatory element-gene pairs. Subsequent validation confirmed that regulation of Jun-Dimerization Protein 2, among others, is both YAP1-dependent and functionally consequential for the hepatoblastoma phenotype in human cells and in hepatic malignancies. To expand our efforts to apply multi-omics technologies to disease models, we next engineered a fluorophore-containing murine leukemia virus (MLV-GFP) stably integrated into Jurkat CD4+ T-cells to report on defective transcriptional silencing by the retroelement-silencing complex, HUSH. A CRISPR knockout screen identified DHX29 as essential for HUSH-mediated silencing of newly-integrated retroviruses. Profiling genomic and transcriptomic features of MLV-GFP Jurkat cells after HUSH and DHX29 knockout revealed their epistatic roles in silencing, and revealed a suite of loci targeted by HUSH. Finally, we used site-specific proteomics and chromatin profiling to identify HUSH-associated factors at the newly integrated proviral reporter.
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Muscle dysfunction in a zebrafish model of Duchenne muscular dystrophySapje zebrafish lack the protein dystrophin and are the smallest vertebrate model of Duchenne muscular dystrophy (DMD). Their small size makes them ideal for large-scale drug discovery screens. However, the extent that sapje mimic the muscle dysfunction of higher vertebrate models of DMD is unclear. We used an optical birefringence assay to differentiate affected dystrophic sapje larvae from their unaffected siblings and then studied trunk muscle contractility at 4-7 days post fertilization. Preparation cross-sectional area (CSA) was similar for affected and unaffected larvae, yet tetanic forces of affected preparations were only 30-60% of normal. ANCOVA indicated that the linear relationship observed between tetanic force and CSA for unaffected preparations was absent in the affected population. Consequently, the average force/CSA of affected larvae was depressed 30-70%. Disproportionate reductions in twitch vs. tetanic force, and a slowing of twitch tension development and relaxation, indicated that the myofibrillar disorganization evident in the birefringence assay could not explain the entire force loss. Single eccentric contractions, in which activated preparations were lengthened 5-10%, resulted in tetanic force deficits in both groups of larvae. However, deficits of affected preparations were 3 to 5-fold greater at all strains and ages, even after accounting for any recovery. Based on these functional assessments, we conclude that the sapje mutant zebrafish is a phenotypically severe model of DMD. The severe contractile deficits of sapje larvae represent novel physiological endpoints for therapeutic drug screening.