Similar Datasets
Project description:Dysregulated translation is a common feature of cancer. Uncovering its governing factors and underlying mechanism are important for cancer therapy. Here, we report that enhancer of zeste homologue 2 (EZH2), previously known as a transcription repressor and lysine methyltransferase, can directly interact with fibrillarin (FBL) to exert its role in translational regulation. We demonstrate that EZH2 enhances rRNA 2'-O methylation via its direct interaction with FBL. Mechanistically, EZH2 strengthens the FBL-NOP56 interaction and facilitates the assembly of box C/D small nucleolar ribonucleoprotein. Strikingly, EZH2 deficiency impairs the translation process globally and reduces internal ribosome entry site (IRES)-dependent translation initiation in cancer cells. Our findings reveal a previously unrecognized role of EZH2 in cancer-related translational regulation.
| S-EPMC8162121 | biostudies-literature
Project description:Overactivated ribosome biogenesis is a common feature of cancer. However, the underlying molecular mechanism remains elusive. Herein, we report enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, could interact with fibrillarin (FBL) directly in the nucleolus. While loss of EZH2 does not impact FBL-mediated histone H2AQ104 methylation (H2AQ104me) and 18S rRNA processing, EZH2 is proved to be involved in rRNA 2′-O methylation in a manner dependent of its interaction with FBL. Mechanistically, EZH2 strengthens the fibrillarin (FBL)-NOP56 interaction by binding to both proteins and thus facilitates the assembly of box C/D small nucleolar ribonucleoprotein (box C/D snoRNP). Strikingly, EZH2 deficiency alters translational efficiency and reduces internal ribosome entry site (IRES) activity of key oncogenes in prostate cancer. In summary, our findings reveal a novel non-methyltransferase role of EZH2 that mediates FBL functions, which may provide more options for the development of EZH2-targeting curative strategies in cancer.
2020-12-10 | GSE143975 | GEO
Project description:Overactivated ribosome biogenesis is a common feature of cancer. However, the underlying molecular mechanism remains elusive. Herein, we report enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, could interact with fibrillarin (FBL) directly in the nucleolus. While loss of EZH2 does not impact FBL-mediated histone H2AQ104 methylation (H2AQ104me) and 18S rRNA processing, EZH2 is proved to be involved in rRNA 2′-O methylation in a manner dependent of its interaction with FBL. Mechanistically, EZH2 strengthens the fibrillarin (FBL)-NOP56 interaction by binding to both proteins and thus facilitates the assembly of box C/D small nucleolar ribonucleoprotein (box C/D snoRNP). Strikingly, EZH2 deficiency alters translational efficiency and reduces internal ribosome entry site (IRES) activity of key oncogenes in prostate cancer. In summary, our findings reveal a novel non-methyltransferase role of EZH2 that mediates FBL functions, which may provide more options for the development of EZH2-targeting curative strategies in cancer.
2020-12-10 | GSE159004 | GEO
Project description:A PRC2-independent function for EZH2 in regulating rRNA 2′-O methylation and IRES-dependent translation
| PRJNA667336 | ENA
Project description:A PRC2-independent function for EZH2 in regulating rRNA 2′-O methylation and IRES-dependent translation
| PRJNA602407 | ENA
Project description:A PRC2-independent function for EZH2 in regulating rRNA 2′-O methylation and IRES-dependent translation
| PRJNA667337 | ENA
Project description:The type II arginine methyltransferase PRMT5 is responsible for the symmetric dimethylation of histone to generate the H3R8me2s and H4R3me2s marks, which correlate with the repression of transcription. However, the protein level of a number of genes (MEP50, CCND1, MYC, HIF1a, MTIF and CDKN1B) are reported to be downregulated by the loss of PRMT5, while their mRNA levels remain unchanged, which is counterintuitive for PRMT5's proposed role as a transcription repressor. We noticed that the majority of the genes regulated by PRMT5, at the posttranscriptional level, express mRNA containing an internal ribosome entry site (IRES). Using an IRES-dependent reporter system, we established that PRMT5 facilitates the translation of a subset of IRES-containing genes. The heterogeneous nuclear ribonucleoprotein, hnRNP A1, is an IRES transacting factor (ITAF) that regulates the IRES-dependent translation of Cyclin D1 and c-Myc. We showed that hnRNP A1 is methylated by PRMT5 on two residues, R218 and R225, and that this methylation facilitates the interaction of hnRNP A1 with IRES RNA to promote IRES-dependent translation. This study defines a new role for PRMT5 regulation of cellular protein levels, which goes beyond the known functions of PRMT5 as a transcription and splicing regulator.
| S-EPMC5416833 | biostudies-literature
Project description:Both gene repressor (Polycomb-dependent) and activator (Polycomb-independent) functions of the Polycomb protein enhancer of zeste homolog 2 (EZH2) are implicated in cancer progression. EZH2 protein can be phosphorylated at various residues, such as threonine 487 (T487), by CDK1 kinase, and such phosphorylation acts as a Polycomb repressive complex 2 (PRC2) suppression "code" to mediate the gene repressor-to-activator switch of EZH2 functions. Here we demonstrate that the histone reader protein ZMYND8 is overexpressed in human clear cell renal cell carcinoma (ccRCC). ZMYND8 binds to EZH2, and their interaction is largely enhanced by CDK1 phosphorylation of EZH2 at T487. ZMYND8 depletion not only enhances Polycomb-dependent function of EZH2 in hypoxia-exposed breast cancer cells or von Hippel-Lindau (VHL)-deficient ccRCC cells, but also suppresses the FOXM1 transcription program. We further show that ZMYND8 is required for EZH2-FOXM1 interaction and is important for FOXM1-dependent matrix metalloproteinase (MMP) gene expression and EZH2-mediated migration and invasion of VHL-deficient ccRCC cells. Our results identify a previously uncharacterized role of the chromatin reader ZMYND8 in recognizing the PRC2-inhibitory phosphorylation "code" essential for the Polycomb-dependent to -independent switch of EZH2 functions. They also reveal an oncogenic pathway driving cell migration and invasion in hypoxia-inducible factor-activated (hypoxia or VHL-deficient) cancer.
| S-EPMC7923384 | biostudies-literature
Project description:The ribosome is indispensable for precisely controlling the capacity of protein synthesis. However, how translational machinery is coordinated to meet the translational demands remains elusive. Here, we identify a nucleolar-specific lncRNA (LoNA), its 5' portion binds and sequesters nucleolin to suppress rRNA transcription, and its snoRNA like 3' end recruits and diminishes fibrillarin activity to reduce rRNA methylation. Activity-dependent decrease of LoNA leads to elevated rRNA and ribosome levels, an increased proportion of polysomes, mRNA polysome loading, and protein translation. In addition, transport of ribosomes to synapses is particularly promoted, resulting in increased levels of AMPA/NMDA receptor, enhanced synaptic plasticity, long-term potentiation and consolidated memory. Strikingly, hippocampal LoNA deficiency not only enhances long-term memory in WT mice, but also restores impaired memory function in APP/PS1 transgenic mice. Together, these findings reveal the multifaceted role of LoNA in modulating ribosome biogenesis to meet the translational demands of long-term memory.
| S-EPMC5928123 | biostudies-literature
Project description:A growing number of studies have focused on the involvement of non-coding RNAs (ncRNAs) in the internal ribosome entry site (IRES)-mediated translation in tumorigenesis; however, the underlying mechanisms in colorectal cancer (CRC) remain elusive. In this study, we show that LINC00473 (LNC473) exerted its functions as a tumor suppressor in promoting apoptotic protease-activating factor 1 (APAF1) IRES activity through competitively sponging miR574-5p and miR15b-5p in CRC initiation and pathogenesis. Specifically, LNC473 and its downstream target APAF1 were significantly downregulated accompanied by upregulated miR574-5p and miR15b-5p in CRC cells and tissues, which had a significant prognostic impact on clinical outcomes in our CRC cohort (n = 157). Furthermore, ectopic LNC473 significantly sponged endogenous miR574-5p or miR15b-5p and thereby inhibited cell proliferation and colony formation capacity, and it accelerated cell apoptosis through activating the APAF1-CASP9-CASP3 pathway. Notably, LNC473 overexpression resulted in dramatic promotion of APAF1 IRES activity and translation, whereas rescue experiments confirmed the recovery by the existence of LNC473 and miR574/15b-5p. Mechanistically, LNC473 overexpression promoted IRES binding domain exposure and removed the constraints controlling from miR574-5p and miR15b-5p, and subsequently enhanced IRES-mediated APAF1 expression in vitro and in vivo. Therefore, our results uncover a novel LNC473-miR574/miR15b-APAF1 signaling axis, which provides new targets and crosstalk regulation mechanism for CRC prevention and treatment.
| S-EPMC7419277 | biostudies-literature