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Project description:Plant Homeo Domain (PHD) is a versatile chromatin reader/effector module which recognizes methylated, acetylated or unmodified histone substrates and regulates cellular gene expression programs. Although PHD domains shows selective epigenetic recognition of methylated, acetylated and unmodified histone substrates, there has been no previous report on its catalytic function regulating malignant transformation of cells. Here we report that PHD finger of UBR7 (Ubiquitin Protein Ligase E3 Component N-Recognin 7 (Putative)), in isolation or in context of full length protein, harbors E3 ubiquitin ligase activity towards monoubiquitination of histone H2B at lysine 120 . Knockdown of UBR7 in MCF10a and breast cancer cells decreased H2BK120ub both at the global levels and on specific genes. Conversely, overexpression of wild type, but not catalytic mutant, rescued H2BK120ub levels. Low UBR7 expression was associated with basal-like and triple negative breast cancers as well as showed poor expression in metastatic tumors. Consistently, UBR7 loss resulted in invasion properties, induced epithelial-to-mesenchymal transition and promoted metastasis. Conversely, ectopic expression of UBR7 reduced cell growth, invasion and tumor growth in mouse fat pad. Mechanistically, UBR7 reduced H2BK120ub gene body of cell-adhesion related genes as well as gene expression including on CDH4 gene. Importantly, rebuilding CDH4 levels rescued invasion phenotypes seen in UBR7-low cells. Collectively, our results establish that UBR7 PHD has novel H2B ubiquitin ligase activity and it suppresses tumor growth in basal-like breast cancers.
2019-02-08 | GSE93758 | GEO
Project description:Plant Homeo Domain (PHD) is a versatile chromatin reader/effector module which recognizes methylated, acetylated or unmodified histone substrates and regulates cellular gene expression programs. Although PHD domains shows selective epigenetic recognition of methylated, acetylated and unmodified histone substrates, there has been no previous report on its catalytic function regulating malignant transformation of cells. Here we report that PHD finger of UBR7 (Ubiquitin Protein Ligase E3 Component N-Recognin 7 (Putative)), in isolation or in context of full length protein, harbors E3 ubiquitin ligase activity towards monoubiquitination of histone H2B at lysine 120 . Knockdown of UBR7 in MCF10a and breast cancer cells decreased H2BK120ub both at the global levels and on specific genes. Conversely, overexpression of wild type, but not catalytic mutant, rescued H2BK120ub levels. Low UBR7 expression was associated with basal-like and triple negative breast cancers as well as showed poor expression in metastatic tumors. Consistently, UBR7 loss resulted in invasion properties, induced epithelial-to-mesenchymal transition and promoted metastasis. Conversely, ectopic expression of UBR7 reduced cell growth, invasion and tumor growth in mouse fat pad. Mechanistically, UBR7 reduced H2BK120ub gene body of cell-adhesion related genes as well as gene expression including on CDH4 gene. Importantly, rebuilding CDH4 levels rescued invasion phenotypes seen in UBR7-low cells. Collectively, our results establish that UBR7 PHD has novel H2B ubiquitin ligase activity and it suppresses tumor growth in basal-like breast cancers.
2019-02-08 | GSE93757 | GEO
Project description:UBR7 is a novel E3 ubiquitin ligase for H2BK120 and acts as a tumor-suppressor in breast cancer
| PRJNA362300 | ENA
Project description:The Hippo kinase pathway is emerging as a conserved signaling pathway that is essential for organ growth and tumorigenesis. Recently, we reported that the ubiquitin E3 ligase ITCH negatively regulates LATS1, thereby increasing YAP activity, which leads to increased cell proliferation and decreased apoptosis. Here, we investigated the role of ITCH in breast tumorigenesis. In particular, we show that ITCH enhances epithelial-to-mesenchymal transition (EMT) through boosting YAP oncogenic function. By contrast, a point mutation in the catalytic domain or WW1 domain of ITCH abolished its EMT-mediated effects. Furthermore, while overexpression of ITCH expression in breast cells is associated with increased incidence of mammary tumor formation and progression, its knockdown inhibited breast cancer cell tumorigenicity and metastasis. Importantly, YAP knockdown was able to attenuate ITCH pro-tumorigenic functions. Lastly, we found that ITCH expression is significantly upregulated in invasive and metastatic breast cancer cases and is associated with worse survival. Together, our results reveal that ITCH pro-tumorigenic functions in breast cancer are mediated, at least in part, through inactivation of the Hippo tumor suppressor pathway.
| S-EPMC4279417 | biostudies-literature
Project description:The roles of Plant Homeodomain (PHD) fingers in catalysis of histone modifications are unknown. We demonstrated that the PHD finger of Ubiquitin Protein Ligase E3 Component N-Recognin7 (UBR7) harbors E3 ubiquitin ligase activity toward monoubiquitination of histone H2B at lysine120 (H2BK120Ub). Purified PHD finger or full-length UBR7 monoubiquitinated H2BK120 in vitro, and loss of UBR7 drastically reduced H2BK120Ub genome-wide binding sites in MCF10A cells. Low UBR7 expression was correlated with occurrence of triple-negative breast cancer and metastatic tumors. Consistently, UBR7 knockdown enhanced the invasiveness, induced epithelial-to-mesenchymal transition and promoted metastasis. Conversely, ectopic expression of UBR7 restored these cellular phenotypes and reduced tumor growth. Mechanistically, UBR7 loss reduced H2BK120Ub levels on cell adhesion genes, including CDH4, and upregulated the Wnt/β-Catenin signaling pathway. CDH4 overexpression could partially revert UBR7-dependent cellular phenotypes. Collectively, our results established UBR7 as a histone H2B monoubiquitin ligase that suppresses tumorigenesis and metastasis of triple-negative breast cancer.
| S-EPMC6438984 | biostudies-literature
Project description:The large tumor suppressor 1 (LATS1) is a serine/threonine kinase and tumor suppressor found down-regulated in a broad spectrum of human cancers. LATS1 is a central player of the emerging Hippo-LATS suppressor pathway, which plays important roles in cell proliferation, apoptosis, and stem cell differentiation. Despite the ample data supporting a role for LATS1 in tumor suppression, how LATS1 is regulated at the molecular level remains largely unknown. In this study, we have identified Itch, a HECT class E3 ubiquitin ligase, as a unique binding partner of LATS1. Itch can complex with LATS1 both in vitro and in vivo through the PPxY motifs of LATS1 and the WW domains of Itch. Significantly, we found that overexpression of Itch promoted LATS1 degradation by polyubiquitination through the 26S proteasome pathway. On the other hand, knockdown of endogenous Itch by shRNAs provoked stabilization of endogenous LATS1 proteins. Finally, through several functional assays, we also revealed that change of Itch abundance alone is sufficient for altering LATS1-mediated downstream signaling, negative regulation of cell proliferation, and induction of apoptosis. Taking these data together, our study identifies E3 ubiquitin ligase Itch as a unique negative regulator of LATS1 and presents a possibility of targeting LATS1/Itch interaction as a therapeutic strategy in cancer.
| S-EPMC3064387 | biostudies-literature
Project description:Human Bre1, an E3 ligase for H2B monoubiquitination, binds p53 and enhances activator-dependent transcription. Ebp1, an ErbB3 receptor-binding protein, inhibits cell proliferation and acts as a tumor suppressor. Here, we show that hBre1 acts as an E3 ubiquitin ligase for Ebp1 tumor suppressor and promotes its polyubiquitination and degradation. Ebp1 is polyubiquitinated in cancer cells, which is regulated by its phosphorylation. We identified hBre1 acting as an E3 ligase for Ebp1 and increasing its polyubiquitination. Depletion of hBre1 blocks Ebp1's polyubiquitination and elevates its protein level, preventing cancer proliferation. hBre1 binds Ebp1 and suppresses its repressive effect on E2F-1. Moreover, Ebp1 protein level is substantially diminished in human cancers. It is robustly phosphorylated and localized in the nucleus of primary gliomas, correlating with hBre1 subcellular residency. Thus, hBre1 inhibits Ebp1's tumor suppressive activity through mediating its polyubiquitination and degradation.
| S-EPMC2633391 | biostudies-literature
Project description:Tumor suppressor p53 has a key role in maintaining genomic stability and preventing tumorigenesis through its regulation of cellular stress responses, including apoptosis, cell cycle arrest and senescence. To ensure its proper levels and functions in cells, p53 is tightly regulated mainly through post-translational modifications, such as ubiquitination. Here, we identified E3 ubiquitin ligase TRIM32 as a novel p53 target gene and negative regulator to regulate p53-mediated stress responses. In response to stress, such as DNA damage, p53 binds to the p53 responsive element in the promoter of the TRIM32 gene and transcriptionally induces the expression of TRIM32 in cells. In turn, TRIM32 interacts with p53 and promotes p53 degradation through ubiquitination. Thus, TRIM32 negatively regulates p53-mediated apoptosis, cell cycle arrest and senescence in response to stress. TRIM32 is frequently overexpressed in different types of human tumors. TRIM32 overexpression promotes cell oncogenic transformation and tumorigenesis in mice in a largely p53-dependent manner. Taken together, our results demonstrated that as a novel p53 target and a novel negative regulator for p53, TRIM32 has an important role in regulation of p53 and p53-mediated cellular stress responses. Furthermore, our results also revealed that impairing p53 function is a novel mechanism for TRIM32 in tumorigenesis.
| S-EPMC4211364 | biostudies-literature
Project description:Mutations of the von Hippel-Lindau (pVHL) tumor suppressor are causative of a familiar predisposition to develop different types of cancer. pVHL is mainly known for its role in regulating hypoxia-inducible factor 1 α (HIF-1α) degradation, thus modulating the hypoxia response. There are different pVHL isoforms, including pVHL30 and pVHL19. However, little is known about isoform-specific functions and protein-protein interactions. Integrating in silico predictions with in vitro and in vivo assays, we describe a novel interaction between pVHL and mouse double minute 2 homolog (MDM2). We found that pVHL30, and not pVHL19, forms a complex with MDM2, and that the N-terminal acidic tail of pVHL30 is required for its association with MDM2. Further, we demonstrate that an intrinsically disordered region upstream of the tetramerization domain of MDM2 is responsible for its isoform-specific association with pVHL30. This region is highly conserved in higher mammals, including primates, similarly to what has been already shown for the N-terminal tail of pVHL30. Finally, we show that overexpression of pVHL30 and MDM2 together reduces cell metabolic activity and necrosis, suggesting a synergistic effect of these E3 ubiquitin ligases. Collectively, our data show an isoform-specific interaction of pVHL with MDM2, suggesting an interplay between these two E3 ubiquitin ligases.
| S-EPMC7522254 | biostudies-literature
Project description:Small ubiquitin-like modifier (SUMO), a member of the ubiquitin-related protein family, is covalently conjugated to lysine residues of its substrates in a process referred to as SUMOylation. SUMOylation occurs through a series of enzymatic reactions analogous to that of the ubiquitination pathway, resulting in modification of the biochemical and functional properties of substrates. To date, four mammalian SUMO isoforms, a single heterodimeric SUMO-activating E1 enzyme SAE1/SAE2, a single SUMO-conjugating E2 enzyme ubiquitin-conjugating enzyme E2I (UBC9), and a few subgroups of SUMO E3 ligases have been identified. Several SUMO E3 ligases such as topoisomerase I binding, arginine/serine-rich (TOPORS), TNF receptor-associated factor 7 (TRAF7), and tripartite motif containing 27 (TRIM27) have dual functions as ubiquitin E3 ligases. Here, we demonstrate that the ubiquitin E3 ligase UHRF2 also acts as a SUMO E3 ligase. UHRF2 effectively enhances zinc finger protein 131 (ZNF131) SUMOylation but does not enhance ZNF131 ubiquitination. In addition, the SUMO E3 activity of UHRF2 on ZNF131 depends on the presence of SET and RING finger-associated and nuclear localization signal-containing region domains, whereas the critical ubiquitin E3 activity RING domain is dispensable. Our findings suggest that UHRF2 has independent functional domains and regulatory mechanisms for these two distinct enzymatic activities.
| S-EPMC3610983 | biostudies-literature