Sir Peter MacCallum Department of Oncology - Research Publications

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Start date: 2020 × End date: 2020 × Type: Preprint ×

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    Altered visual function in a larval zebrafish knockout of neurodevelopmental risk gene
    Xie, J ; Jusuf, PR ; Bui, BV ; Dudczig, S ; Goodbourn, PT ( 2020-09-22)
    The human PDZK1 gene is located in a genomic susceptibility region for neurodevelopmental disorders. A genome-wide association study (GWAS) identified links between PDZK1 polymorphisms and altered visual contrast sensitivity, an endophenotype for schizophrenia and autism spectrum disorder. The PDZK1 protein is implicated in neurological functioning, interacting with synaptic molecules including post-synaptic density 95 (PSD-95), N-methyl-D-aspartate receptors (NMDAR), corticotropin-releasing factor receptor 1 (CRFR1) and serotonin 2A receptors. To elucidate the role of PDZK1, we generated pdzk1-knockout (pdzk1-KO) zebrafish using CRISPR/Cas-9 genome editing. Visual function of 7-day-old fish was assessed at behavioural and functional levels using the optomotor response (OMR) and scotopic electroretinogram (ERG). We also quantified retinal morphology and densities of PSD-95, NMDAR1, CRFR1 and serotonin in the synaptic inner plexiform layer at 7 days, 4 weeks and 8 weeks of age. Relative to wild-type, pdzk1-KO larvae showed spatial-frequency tuning functions with increased amplitude (likely due to abnormal gain control) and reduced ERG b-waves (suggestive of inner retinal dysfunction). However, these functional differences were not associated with gross synaptic or morphological retinal phenotypes. The findings corroborate a role for pdzk1 in visual function, and our model system provides a platform for investigating other genes associated with abnormal visual behaviour.
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    Reprogrammed CRISPR-Cas13b suppresses SARS-CoV-2 replication and circumvents its mutational escape through mismatch tolerance
    Fareh, M ; Zhao, W ; Hu, W ; Casan, JML ; Kumar, A ; Symons, J ; Voskoboinik, I ; Ekert, P ; Rudraraju, R ; Lewin, S ; Trapani, J ( 2020-11-19)

    ABSTRACT

    Mutation-driven evolution of SARS coronavirus-2 (SARS-CoV-2) highlights the need for innovative approaches that simultaneously suppress viral replication and circumvent viral escape routes from host immunity and antiviral therapeutics. Here, we employed genome-wide computational prediction and singlenucleotide resolution screening to reprogram CRISPR-Cas13b against SARS-CoV-2 genomic and subgenomic RNAs. Reprogrammed Cas13b effectors targeting accessible regions of Spike and Nucleocapsid transcripts achieved >98% silencing efficiency in virus free-models. Further, optimized and multiplexed gRNAs suppressed viral replication by up to 90% in mammalian cells infected with replication-competent SARS-CoV-2. Unexpectedly, the comprehensive mutagenesis of guide-target interaction demonstrated that single-nucleotide mismatches do not impair the capacity of a potent single gRNA to simultaneously suppress ancestral and mutated SARS-CoV-2 in infected mammalian cells, including the highly infectious and globally disseminated Spike D614G mutant. The specificity, efficiency and rapid deployment properties of reprogrammed Cas13b described here provide a molecular blueprint of antiviral therapeutics to simultaneously suppress a wide range of SARS-CoV-2 mutants, and is readily adaptable to other emerging pathogenic viruses.
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    Epigenetic reprogramming of plasmacytoid dendritic cells drives type I interferon-dependent differentiation of acute myeloid leukemias for therapeutic benefit
    Salmon, J ; Todorovski, I ; Vervoort, S ; Stanley, K ; Kearney, C ; Martelotto, L ; Rossello, F ; Semple, T ; Mir-Arnau, G ; Zethoven, M ; Bots, M ; Vidacs, E ; McArthur, K ; Gressier, E ; de Weerd, N ; Lichte, J ; Kelly, M ; Cluse, L ; Hogg, S ; Hertzog, P ; Kats, L ; de Carvalho, D ; Scheu, S ; Bedoui, S ; Kile, B ; Wei, A ; Dominguez, P ; Johnstone, R ( 2020-08-24)
    Pharmacological inhibition of epigenetic enzymes can have therapeutic benefit, particularly against hematological malignancies. While these agents can affect tumor cell growth and proliferation, recent studies have demonstrated that pharmacological de-regulation of epigenetic modifiers may additionally mediate anti-tumor immune responses. Here we discovered a novel mechanism of immune regulation through the inhibition of histone deacetylases (HDACs). In a genetically engineered model of t(8;21) AML, leukemia cell differentiation and therapeutic benefit mediated by the HDAC inhibitor panobinostat required activation of the type I interferon (IFN) signaling pathway. Plasmacytoid dendritic cells (pDCs) were identified as the cells producing type I IFN in response to panobinostat, through transcriptional activation of IFN genes concomitant with increased H3K27 acetylation at these loci. Depletion of pDCs abrogated panobinostat-mediated activation of type I IFN signaling in leukemia cells and impaired therapeutic efficacy, while combined treatment of panobinostat and recombinant IFNα improved therapeutic outcomes. These discoveries offer a new therapeutic approach for t(8;21) AML and demonstrate that epigenetic rewiring of pDCs enhances anti-tumor immunity, opening the possibility of exploiting this cell type as a new target for immunotherapy.