Project description:The Sp100 component of ND10/PML bodies is a potent tumor suppressor: accelerated senescence and rapid malignant transformation of human fibroblasts through modulation of an embryonic stem cell program. Identifying the functions of proteins, which define specific subnuclear structures and territories, is important for understanding eukaryotic nuclear dynamics. Sp100 is a prototypical protein of ND10/PML bodies and colocalizes with the proto-oncogenic protein PML and Daxx, proteins with critical roles in oncogenic transformation, interferon-mediated viral resistance and response to PML-directed cancer therapeutics. Sp100 isoforms contain PHD, Bromo and HMG domains and are highly sumoylated at ND10/PML bodies, all characteristics suggestive of a role in chromatin mediated gene regulation. However, a clear role for Sp100 in oncogenesis has not been defined. Using isoform-specific knockdown techniques, we show that most human diploid fibroblasts, which lack Sp100, rapidly senesce. microarray analysis of mRNAs expression in BJV (collected at passage 47) and BJ-S (collected at passage 35). In addition, samples were treated for 24 h with 1000 U/ml IFNB. All RNAs were collected in triplicates of biological samples.
Project description:Stimulation of the innate immune system by foreign RNA elicits a potent interferon response and can trigger cell death. The mechanisms by which cells balance a robust response with cell-intrinsic lethality are still being uncovered. Employing genome-wide CRISPR-Cas9 genetic screens with triphosphorylated RNA stimulation, we discovered that the promyelocytic leukemia (PML) nuclear body-localized speckled protein 110 (SP110) is a potent inhibitor of type 1 interferon-driven cell death. Death suppression by SP110 counteracts a toxic activity of SP100, a major constituent of PML bodies. Loss of SP110 leads to mitotic retention of SP100 and PML bodies which associate with and perturb segregating chromosomes leading to micronucleus formation, DNA damage, and genotoxic cell death. A combination of cryo-electron microscopy, AlphaFold modeling, and cellular biochemistry reveals that SP110 dissolves toxic SP100 oligomers via necessary and sufficient direct interactions between their caspase activation and recruitment domains (CARDs). These data reveal critical roles of SP100 and SP110 in governing disassembly of PML bodies during mitosis and the repercussions if this process is mis-regulated.
Project description:Identifying the functions of proteins, which define specific subnuclear structures and territories, is important for understanding eukaryotic nuclear dynamics. Sp100 is a prototypical protein of ND10/PML bodies and co-localizes with the proto-oncogenic protein PML and Daxx, proteins with critical roles in oncogenic transformation, interferon-mediated viral resistance and response to PML-directed cancer therapeutics. Sp100 isoforms contain PHD, Bromo and HMG domains and are highly sumoylated at ND10/PML bodies, all characteristics suggestive of a role in chromatin mediated gene regulation. However, no clear role for the Sp100 component of PML bodies in oncogenesis has been defined. Using isoform-specific knockdown techniques, we show that most human diploid fibroblasts, which lack Sp100, rapidly senesce and discuss gene expression changes associated with this rapid senescence.
Project description:The alternative splicing of PML precursor mRNA gives rise to various PML isoforms, yet their expression profile in breast cancer cells remains uncharted. We discovered that PML1 is the most abundant isoform in all breast cancer subtypes, and its expression is associated with unfavorable prognosis in estrogen receptor-positive (ER+) breast cancers. PML depletion reduces cell proliferation, invasion, and stemness, while heterologous PML1 expression augments these processes and fuels tumor growth and resistance to fulvestrant, an FDA-approved drug for ER+ breast cancer, in a mouse model. Moreover, PML1, rather than the well-known tumor suppressor isoform PML4, rescues the proliferation of PML knockdown cells. ChIP-seq analysis reveals significant overlap between PML-, ER-, and Myc-bound promoters, suggesting their coordinated regulation of target gene expression, including genes involved in breast cancer stem cells (BCSCs), such as JAG1, KLF4, YAP1, SNAI1, and MYC. Loss of PML reduces BCSC-related gene expression, and exogenous PML1 expression elevates their expression. Consistently, PML1 restores the association of PML with these promoters in PML-depleted cells. We identified a novel association between PML1 and WDR5, a key component of H3K4 methyltransferase (HMTs) complexes that catalyze H3K4me1 and H3K4me3. ChIP-seq analyses showed that the loss of PML1 reduces H3K4me3 in numerous loci, including BCSC-associated gene promoters. Additionally, PML1, not PML4, re-establishes the H3K4me3 mark on these promoters in PML-depleted cells. Significantly, PML1 is essential for recruiting WDR5, MLL1, and MLL2 to these gene promoters. Inactivating WDR5 by knockdown or inhibitors phenocopies the effects of PML1 loss, reducing BCSC-related gene expression and tumorsphere formation and enhancing fulvestrant’s anticancer activity. Our findings challenge the conventional understanding of PML as a tumor suppressor, redefine its role as a promoter of tumor growth in breast cancer and offer new insights into the unique roles of PML isoforms in breast cancer.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.