School of Mathematics and Statistics - Research Publications

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    Three-dimensional genome architecture coordinates key regulators of lineage specification in mammary epithelial cells
    Milevskiy, MJG ; Coughlan, HD ; Kane, SR ; Johanson, TM ; Kordafshari, S ; Chan, WF ; Tsai, M ; Surgenor, E ; Wilcox, S ; Allan, RS ; Chen, Y ; Lindeman, GJ ; Smyth, GK ; Visvader, JE (ELSEVIER, 2023-11-08)
    Although lineage-specific genes have been identified in the mammary gland, little is known about the contribution of the 3D genome organization to gene regulation in the epithelium. Here, we describe the chromatin landscape of the three major epithelial subsets through integration of long- and short-range chromatin interactions, accessibility, histone modifications, and gene expression. While basal genes display exquisite lineage specificity via distal enhancers, luminal-specific genes show widespread promoter priming in basal cells. Cell specificity in luminal progenitors is largely mediated through extensive chromatin interactions with super-enhancers in gene-body regions in addition to interactions with polycomb silencer elements. Moreover, lineage-specific transcription factors appear to be controlled through cell-specific chromatin interactivity. Finally, chromatin accessibility rather than interactivity emerged as a defining feature of the activation of quiescent basal stem cells. This work provides a comprehensive resource for understanding the role of higher-order chromatin interactions in cell-fate specification and differentiation in the adult mouse mammary gland.
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    HBO1 (KAT7) Does Not Have an Essential Role in Cell Proliferation, DNA Replication, or Histone 4 Acetylation in Human Cells
    Kueh, AJ ; Eccles, S ; Tang, L ; Garnham, AL ; May, RE ; Herold, MJ ; Smyth, GK ; Voss, AK ; Thomas, T (American Society for Microbiology, 2020-02-01)
    HBO1 (MYST2/KAT7) is essential for histone 3 lysine 14 acetylation (H3K14ac) but is dispensable for H4 acetylation and DNA replication in mouse tissues. In contrast, previous studies using small interfering RNA (siRNA) knockdown in human cell lines have suggested that HBO1 is essential for DNA replication. To determine if HBO1 has distinctly different roles in immortalized human cell lines and normal mouse cells, we performed siRNA knockdown of HBO1. In addition, we used CRISPR/Cas9 to generate 293T, MCF7, and HeLa cell lines lacking HBO1. Using both techniques, we show that HBO1 is essential for all H3K14ac in human cells and is unlikely to have a direct effect on H4 acetylation and only has minor effects on cell proliferation. Surprisingly, the loss of HBO1 and H3K14ac in HeLa cells led to the secondary loss of almost all H4 acetylation after 4 weeks. Thus, HBO1 is dispensable for DNA replication and cell proliferation in immortalized human cells. However, while cell proliferation proceeded without HBO1 and H3K14ac, HBO1 gene deletion led to profound changes in cell adhesion, particularly in 293T cells. Consistent with this phenotype, the loss of HBO1 in both 293T and HeLa principally affected genes mediating cell adhesion, with comparatively minor effects on other cellular processes.
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    Gata-3 Negatively Regulates the Tumor-Initiating Capacity of Mammary Luminal Progenitor Cells and Targets the Putative Tumor Suppressor Caspase-14
    Asselin-Labat, M-L ; Sutherland, KD ; Vaillant, F ; Gyorki, DE ; Wu, D ; Holroyd, S ; Breslin, K ; Ward, T ; Shi, W ; Bath, ML ; Deb, S ; Fox, SB ; Smyth, GK ; Lindeman, GJ ; Visvader, JE (AMER SOC MICROBIOLOGY, 2011-11)
    The transcription factor Gata-3 is a definitive marker of luminal breast cancers and a key regulator of mammary morphogenesis. Here we have explored a role for Gata-3 in tumor initiation and the underlying cellular mechanisms using a mouse model of "luminal-like" cancer. Loss of a single Gata-3 allele markedly accelerated tumor progression in mice carrying the mouse mammary tumor virus promoter-driven polyomavirus middle T antigen (MMTV-PyMT mice), while overexpression of Gata-3 curtailed tumorigenesis. Through the identification of two distinct luminal progenitor cells in the mammary gland, we demonstrate that Gata-3 haplo-insufficiency increases the tumor-initiating capacity of these progenitors but not the stem cell-enriched population. Overexpression of a conditional Gata-3 transgene in the PyMT model promoted cellular differentiation and led to reduced tumor-initiating capacity as well as diminished angiogenesis. Transcript profiling studies identified caspase-14 as a novel downstream target of Gata-3, in keeping with its roles in differentiation and tumorigenesis. A strong association was evident between GATA-3 and caspase-14 expression in preinvasive ductal carcinoma in situ samples, where GATA-3 also displayed prognostic significance. Overall, these studies identify GATA-3 as an important regulator of tumor initiation through its ability to promote the differentiation of committed luminal progenitor cells.
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    Overexpression of Lmo2 initiates T-lymphoblastic leukemia via impaired thymocyte competition
    Abdulla, HDD ; Alserihi, R ; Flensburg, C ; Abeysekera, W ; Luo, M-X ; Gray, DHD ; Liu, X ; Smyth, GKK ; Alexander, WSS ; Majewski, IJJ ; McCormack, MPP (ROCKEFELLER UNIV PRESS, 2023-03-15)
    Cell competition has recently emerged as an important tumor suppressor mechanism in the thymus that inhibits autonomous thymic maintenance. Here, we show that the oncogenic transcription factor Lmo2 causes autonomous thymic maintenance in transgenic mice by inhibiting early T cell differentiation. This autonomous thymic maintenance results in the development of self-renewing preleukemic stem cells (pre-LSCs) and subsequent leukemogenesis, both of which are profoundly inhibited by restoration of thymic competition or expression of the antiapoptotic factor BCL2. Genomic analyses revealed the presence of Notch1 mutations in pre-LSCs before subsequent loss of tumor suppressors promotes the transition to overt leukemogenesis. These studies demonstrate a critical role for impaired cell competition in the development of pre-LSCs in a transgenic mouse model of T cell acute lymphoblastic leukemia (T-ALL), implying that this process plays a role in the ontogeny of human T-ALL.
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    Stem cell plasticity, acetylation of H3K14, and de novo gene activation rely on KAT7.
    Kueh, AJ ; Bergamasco, MI ; Quaglieri, A ; Phipson, B ; Li-Wai-Suen, CSN ; Lönnstedt, IM ; Hu, Y ; Feng, Z-P ; Woodruff, C ; May, RE ; Wilcox, S ; Garnham, AL ; Snyder, MP ; Smyth, GK ; Speed, TP ; Thomas, T ; Voss, AK (Elsevier BV, 2023-01-31)
    In the conventional model of transcriptional activation, transcription factors bind to response elements and recruit co-factors, including histone acetyltransferases. Contrary to this model, we show that the histone acetyltransferase KAT7 (HBO1/MYST2) is required genome wide for histone H3 lysine 14 acetylation (H3K14ac). Examining neural stem cells, we find that KAT7 and H3K14ac are present not only at transcribed genes but also at inactive genes, intergenic regions, and in heterochromatin. KAT7 and H3K14ac were not required for the continued transcription of genes that were actively transcribed at the time of loss of KAT7 but indispensable for the activation of repressed genes. The absence of KAT7 abrogates neural stem cell plasticity, diverse differentiation pathways, and cerebral cortex development. Re-expression of KAT7 restored stem cell developmental potential. Overexpression of KAT7 enhanced neuron and oligodendrocyte differentiation. Our data suggest that KAT7 prepares chromatin for transcriptional activation and is a prerequisite for gene activation.
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    Activation of stably silenced genes by recruitment of a synthetic de-methylating module
    Chan, WF ; Coughlan, HD ; Chen, Y ; Keenan, CR ; Smyth, GK ; Perkins, AC ; Johanson, TM ; Allan, RS (NATURE PORTFOLIO, 2022-09-23)
    Stably silenced genes that display a high level of CpG dinucleotide methylation are refractory to the current generation of dCas9-based activation systems. To counter this, we create an improved activation system by coupling the catalytic domain of DNA demethylating enzyme TET1 with transcriptional activators (TETact). We show that TETact demethylation-coupled activation is able to induce transcription of suppressed genes, both individually and simultaneously in cells, and has utility across a number of cell types. Furthermore, we show that TETact can effectively reactivate embryonic haemoglobin genes in non-erythroid cells. We anticipate that TETact will expand the existing CRISPR toolbox and be valuable for functional studies, genetic screens and potential therapeutics.
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    Loss of TIP60 (KAT5) abolishes H2AZ lysine 7 acetylation and causes p53, INK4A, and ARF-independent cell cycle arrest
    Wichmann, J ; Pitt, C ; Eccles, S ; Garnham, AL ; Li-Wai-Suen, CSN ; May, R ; Allan, E ; Wilcox, S ; Herold, MJ ; Smyth, GK ; Monahan, BJ ; Thomas, T ; Voss, AK (SPRINGERNATURE, 2022-07-20)
    Histone acetylation is essential for initiating and maintaining a permissive chromatin conformation and gene transcription. Dysregulation of histone acetylation can contribute to tumorigenesis and metastasis. Using inducible cre-recombinase and CRISPR/Cas9-mediated deletion, we investigated the roles of the histone lysine acetyltransferase TIP60 (KAT5/HTATIP) in human cells, mouse cells, and mouse embryos. We found that loss of TIP60 caused complete cell growth arrest. In the absence of TIP60, chromosomes failed to align in a metaphase plate during mitosis. In some TIP60 deleted cells, endoreplication occurred instead. In contrast, cell survival was not affected. Remarkably, the cell growth arrest caused by loss of TIP60 was independent of the tumor suppressors p53, INK4A and ARF. TIP60 was found to be essential for the acetylation of H2AZ, specifically at lysine 7. The mRNA levels of 6236 human and 8238 mouse genes, including many metabolism genes, were dependent on TIP60. Among the top 50 differentially expressed genes, over 90% were downregulated in cells lacking TIP60, supporting a role for TIP60 as a key co-activator of transcription. We propose a primary role of TIP60 in H2AZ lysine 7 acetylation and transcriptional activation, and that this fundamental role is essential for cell proliferation. Growth arrest independent of major tumor suppressors suggests TIP60 as a potential anti-cancer drug target.
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    Molecular profiling reveals features of clinical immunity and immunosuppression in asymptomatic P. falciparum malaria
    Studniberg, S ; Ioannidis, LJ ; Utami, RAS ; Trianty, L ; Liao, Y ; Abeysekera, W ; Li-Wai-Suen, CSN ; Pietrzak, HM ; Healer, J ; Puspitasari, AM ; Apriyanti, D ; Coutrier, F ; Poespoprodjo, JR ; Kenangalem, E ; Andries, B ; Prayoga, P ; Sariyanti, N ; Smyth, GK ; Cowman, AF ; Price, RN ; Noviyanti, R ; Shi, W ; Garnham, AL ; Hansen, DS (WILEY, 2022-04)
    Clinical immunity to P. falciparum malaria is non-sterilizing, with adults often experiencing asymptomatic infection. Historically, asymptomatic malaria has been viewed as beneficial and required to help maintain clinical immunity. Emerging views suggest that these infections are detrimental and constitute a parasite reservoir that perpetuates transmission. To define the impact of asymptomatic malaria, we pursued a systems approach integrating antibody responses, mass cytometry, and transcriptional profiling of individuals experiencing symptomatic and asymptomatic P. falciparum infection. Defined populations of classical and atypical memory B cells and a TH2 cell bias were associated with reduced risk of clinical malaria. Despite these protective responses, asymptomatic malaria featured an immunosuppressive transcriptional signature with upregulation of pathways involved in the inhibition of T-cell function, and CTLA-4 as a predicted regulator in these processes. As proof of concept, we demonstrated a role for CTLA-4 in the development of asymptomatic parasitemia in infection models. The results suggest that asymptomatic malaria is not innocuous and might not support the induction of immune processes to fully control parasitemia or efficiently respond to malaria vaccines.
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    Targeting histone acetylation dynamics and oncogenic transcription by catalytic P300/CBP inhibition
    Hogg, SJ ; Motorna, O ; Cluse, LA ; Johanson, TM ; Coughlan, HD ; Raviram, R ; Myers, RM ; Costacurta, M ; Todorovski, I ; Pijpers, L ; Bjelosevic, S ; Williams, T ; Huskins, SN ; Kearney, CJ ; Devlin, JR ; Fan, Z ; Jabbari, JS ; Martin, BP ; Fareh, M ; Kelly, MJ ; Dupere-Richer, D ; Sandow, JJ ; Feran, B ; Knight, D ; Khong, T ; Spencer, A ; Harrison, SJ ; Gregory, G ; Wickramasinghe, VO ; Webb, A ; Taberlay, PC ; Bromberg, KD ; Lai, A ; Papenfuss, AT ; Smyth, GK ; Allan, RS ; Licht, JD ; Landau, DA ; Abdel-Wahab, O ; Shortt, J ; Vervoort, SJ ; Johnstone, RW (CELL PRESS, 2021-05-20)
    To separate causal effects of histone acetylation on chromatin accessibility and transcriptional output, we used integrated epigenomic and transcriptomic analyses following acute inhibition of major cellular lysine acetyltransferases P300 and CBP in hematological malignancies. We found that catalytic P300/CBP inhibition dynamically perturbs steady-state acetylation kinetics and suppresses oncogenic transcriptional networks in the absence of changes to chromatin accessibility. CRISPR-Cas9 screening identified NCOR1 and HDAC3 transcriptional co-repressors as the principal antagonists of P300/CBP by counteracting acetylation turnover kinetics. Finally, deacetylation of H3K27 provides nucleation sites for reciprocal methylation switching, a feature that can be exploited therapeutically by concomitant KDM6A and P300/CBP inhibition. Overall, this study indicates that the steady-state histone acetylation-methylation equilibrium functions as a molecular rheostat governing cellular transcription that is amenable to therapeutic exploitation as an anti-cancer regimen.
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    The concerted change in the distribution of cell cycle phases and zone composition in germinal centers is regulated by IL-21
    Zotos, D ; Quast, I ; Li-Wai-Suen, CSN ; McKenzie, CI ; Robinson, MJ ; Kan, A ; Smyth, GK ; Hodgkin, PD ; Tarlinton, DM (NATURE PORTFOLIO, 2021-12-09)
    Humoral immune responses require germinal centres (GC) for antibody affinity maturation. Within GC, B cell proliferation and mutation are segregated from affinity-based positive selection in the dark zone (DZ) and light zone (LZ) substructures, respectively. While IL-21 is known to be important in affinity maturation and GC maintenance, here we show it is required for both establishing normal zone representation and preventing the accumulation of cells in the G1 cell cycle stage in the GC LZ. Cell cycle progression of DZ B cells is unaffected by IL-21 availability, as is the zone phenotype of the most highly proliferative GC B cells. Collectively, this study characterises the development of GC zones as a function of time and B cell proliferation and identifies IL-21 as an important regulator of these processes. These data help explain the requirement for IL-21 in normal antibody affinity maturation.