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1.
Life Sci ; 235: 116785, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31445025

RESUMO

AIMS: Hsa_circ_0007534 has been reported to be a novel cancer-related circRNA affecting multiple cancers. However, little is known about the role of hsa_circ_0007534 in cervical cancer specifically. In the current study, we aimed to explore the expression and function of hsa_circ_0007534 in cervical cancer. MAIN METHODS: The expression of circRNA, miRNA and mRNA was measured using real-time quantitative polymerase chain reactions. Protein expression was assessed by Western blot. Knockdown of has_circ_0007534 was achieved by siRNA-mediated gene silencing. Cell proliferation was determined using a cell counting kit-8 and colony formation assays. Cell invasion was assessed using a Transwell invasion assay. RNA interactions were measured using an RNA pull-down and dual-luciferase reporter assays. KEY FINDINGS: The expression of hsa_circ_0007534 was upregulated in cervical cancer tissues and cell lines. Depletion of hsa_circ_0007534 decreased both the proliferation and invasion of cervical cancer cells. MicroRNA-498 (miR-498) was identified as a target of the miRNA encoded by hsa_circ_0007534. Levels of miR-498 were decreased in cervical cancer tissues, a finding that was inversely correlated with hsa_circ_0007534 expression. miR-498 overexpression repressed the proliferation and invasion of cervical cancer cells. B-cell-specific Moloney murine leukemia virus integration site 1 (BMI-1) was verified as a target gene of miR-498. BMI-1 overexpression reversed the effects of hsa_circ_0007534 depletion or miR-498 overexpression on cervical cancer cell proliferation and invasion. SIGNIFICANCE: Our study demonstrates that downregulation of hsa_circ_0007534 represses the proliferation and invasion of cervical cancer through regulating the miR-498/BMI-1 axis, suggesting the hsa_circ_0007534/miR-498/BMI-1 axis as a potential therapeutic target to treat cervical cancer.


Assuntos
Movimento Celular , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Complexo Repressor Polycomb 1/metabolismo , RNA/genética , Neoplasias do Colo do Útero/patologia , Regulação para Baixo , Feminino , Humanos , Invasividade Neoplásica , Complexo Repressor Polycomb 1/genética , Transdução de Sinais , Células Tumorais Cultivadas , Neoplasias do Colo do Útero/genética , Neoplasias do Colo do Útero/metabolismo
2.
Rinsho Ketsueki ; 60(6): 680-690, 2019.
Artigo em Japonês | MEDLINE | ID: mdl-31281161

RESUMO

Recent progress in whole genome sequencing has identified recurrent somatic mutations in the additional sex combs like 1 (ASXL1) gene in a variety of hematological disorders and even in premalignant conditions. However, the molecular mechanisms regarding the contribution of ASXL1 mutation to the pathogenesis of premalignant conditions remain largely unelucidated. Thus, we investigated the biological effects of mutant Asxl1 using newly-generated knock-in (KI) mice. Heterozygous mutant KI mice developed phenotypes resembling human low-risk myelodysplastic syndromes (MDS), and some of them developed an MDS/myeloproliferative neoplasm-like disease after a long latency. The H2AK119ub1 level around the promoter region of p16Ink4a was significantly decreased in KI hematopoietic stem cells (HSCs), suggesting perturbation of Bmi1-driven H2AK119ub1 histone modification by mutant Asxl1. The mutant Asxl1 failed to interact with Bmi1, although wild type ASXL1 protein did not. When p16Ink4a expression was depleted in Asxl1 KI mice, the HSC pool was restored, and apoptosis was ameliorated in HSCs. These findings demonstrate that the loss of protein interaction between mutant Asxl1 and Bmi1 affected the activity of Prc1. The subsequent derepression of p16Ink4a by aberrant histone ubiquitination could induce cellular senescence, resulting in low-risk MDS-like phenotypes in heterozygous Asxl1 KI mice.


Assuntos
Mutação , Síndromes Mielodisplásicas/genética , Proteínas Repressoras/genética , Animais , Modelos Animais de Doenças , Técnicas de Introdução de Genes , Células-Tronco Hematopoéticas , Histonas/metabolismo , Camundongos , Fenótipo , Complexo Repressor Polycomb 1/genética , Proteínas Proto-Oncogênicas/genética , Ubiquitinação
3.
Gene ; 711: 143949, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31255735

RESUMO

As a transcriptional repressor, Chromobox 8 (CBX8) overexpression is found to be associated with tumorigenesis in several cancers. However, its role in radiotherapy resistance remains poorly characterized. Our study is the first to explore the correlation between CBX8 and radioresistance. We report here that CBX8 is upregulated in Esophageal Squamous Cell Carcinoma (ESCC) tissues and cells and serves as an indicator of poor prognosis for ESCC patients. CBX8 knockdown inhibits cell proliferation, colony formation capability, DNA repair and promotes cell apoptosis. Moreover, the transcriptome sequencing analysis demonstrates that CBX8 downregulates the expression of Apoptotic protease activating factor 1 (APAF1), which is the core protein that mediates mitochondrial apoptotic pathways. APAF1 depletion could abrogate apoptosis induced by CBX8 knockdown in irradiated ESCC cells. Our results provide novel insight into CBX8 as a therapeutic target to improve the radiosensitivity of ESCC.


Assuntos
Fator Apoptótico 1 Ativador de Proteases/genética , Neoplasias Esofágicas/patologia , Carcinoma de Células Escamosas do Esôfago/patologia , Complexo Repressor Polycomb 1/metabolismo , Tolerância a Radiação , Animais , Fator Apoptótico 1 Ativador de Proteases/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Neoplasias Esofágicas/genética , Neoplasias Esofágicas/metabolismo , Carcinoma de Células Escamosas do Esôfago/genética , Carcinoma de Células Escamosas do Esôfago/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Transplante de Neoplasias , Complexo Repressor Polycomb 1/genética , Prognóstico , Regulação para Cima
4.
Nat Commun ; 10(1): 2828, 2019 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-31249301

RESUMO

H2A.Z variant has emerged as a critical player in regulating plant responses to environment; however, the mechanism by which H2A.Z mediates this regulation remains unclear. In Arabidopsis, H2A.Z has been proposed to have opposite effects on transcription depending on its localization within the gene. These opposite roles have been assigned by correlating gene expression and H2A.Z enrichment analyses but without considering the impact of possible H2A.Z post-translational modifications. Here, we show that H2A.Z can be monoubiquitinated by the PRC1 components AtBMI1A/B/C. The incorporation of this modification is required for H2A.Z-mediated transcriptional repression through a mechanism that does not require PRC2 activity. Our data suggest that the dual role of H2A.Z in regulating gene expression depends on the modification that it carries, while the levels of H2A.Z within genes depend on the transcriptional activity.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Histonas/metabolismo , Complexo Repressor Polycomb 1/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Histonas/genética , Complexo Repressor Polycomb 1/genética , Ubiquitinação
5.
Genes Dev ; 33(13-14): 799-813, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31171700

RESUMO

Mammalian development requires effective mechanisms to repress genes whose expression would generate inappropriately specified cells. The Polycomb-repressive complex 1 (PRC1) family complexes are central to maintaining this repression. These include a set of canonical PRC1 complexes, each of which contains four core proteins, including one from the CBX family. These complexes have been shown previously to reside in membraneless organelles called Polycomb bodies, leading to speculation that canonical PRC1 might be found in a separate phase from the rest of the nucleus. We show here that reconstituted PRC1 readily phase-separates into droplets in vitro at low concentrations and physiological salt conditions. This behavior is driven by the CBX2 subunit. Point mutations in an internal domain of Cbx2 eliminate phase separation. These same point mutations eliminate the formation of puncta in cells and have been shown previously to eliminate nucleosome compaction in vitro and generate axial patterning defects in mice. Thus, the domain of CBX2 that is important for phase separation is the same domain shown previously to be important for chromatin compaction and proper development, raising the possibility of a mechanistic or evolutionary link between these activities.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento/genética , Complexo Repressor Polycomb 1/química , Animais , Linhagem Celular , Escherichia coli/genética , Camundongos , Camundongos Endogâmicos C57BL , Células NIH 3T3 , Organelas/metabolismo , Mutação Puntual , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 1/metabolismo , Domínios Proteicos , Células Sf9
6.
Int J Mol Sci ; 20(11)2019 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-31146388

RESUMO

Stem cells undergo senescence both in vivo, contributing to the progressive decline in self-healing mechanisms, and in vitro during prolonged expansion. Here, we show that an early developmental zebrafish embryo extract (ZF1) could act as a modulator of senescence in human mesenchymal stem cells (hMSCs) isolated from both adult tissues, including adipose tissue (hASCs), bone marrow (hBM-MSCs), dental pulp (hDP-MSCs), and a perinatal tissue such as the Wharton's Jelly (hWJ-MSCs). In all the investigated hMSCs, ZF1 decreased senescence-associated ß-galactosidase (SA ß-gal) activity and enhanced the transcription of TERT, encoding the catalytic telomerase core. In addition, it was associated, only in hASCs, with a transcriptional induction of BMI1, a pleiotropic repressor of senescence. In hBM-MSCs, hDP-MSCs, and hWJ-MSCs, TERT over-expression was concomitant with a down-regulation of two repressors of TERT, TP53 (p53), and CDKN1A (p21). Furthermore, ZF1 increased the natural ability of hASCs to perform adipogenesis. These results indicate the chance of using ZF1 to modulate stem cell senescence in a source-related manner, to be potentially used as a tool to affect stem cell senescence in vitro. In addition, its anti-senescence action could also set the basis for future in vivo approaches promoting tissue rejuvenation bypassing stem cell transplantation.


Assuntos
Senescência Celular , Embrião não Mamífero/química , Células-Tronco Mesenquimais/efeitos dos fármacos , Extratos de Tecidos/farmacologia , Animais , Células Cultivadas , Inibidor de Quinase Dependente de Ciclina p21/genética , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 1/metabolismo , Telomerase/genética , Telomerase/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Peixe-Zebra
7.
Nat Commun ; 10(1): 1931, 2019 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-31036804

RESUMO

Polycomb group (PcG) proteins play critical roles in the epigenetic inheritance of cell fate. The Polycomb Repressive Complexes PRC1 and PRC2 catalyse distinct chromatin modifications to enforce gene silencing, but how transcriptional repression is propagated through mitotic cell divisions remains a key unresolved question. Using reversible tethering of PcG proteins to ectopic sites in mouse embryonic stem cells, here we show that PRC1 can trigger transcriptional repression and Polycomb-dependent chromatin modifications. We find that canonical PRC1 (cPRC1), but not variant PRC1, maintains gene silencing through cell division upon reversal of tethering. Propagation of gene repression is sustained by cis-acting histone modifications, PRC2-mediated H3K27me3 and cPRC1-mediated H2AK119ub1, promoting a sequence-independent feedback mechanism for PcG protein recruitment. Thus, the distinct PRC1 complexes present in vertebrates can differentially regulate epigenetic maintenance of gene silencing, potentially enabling dynamic heritable responses to complex stimuli. Our findings reveal how PcG repression is potentially inherited in vertebrates.


Assuntos
Cromatina/metabolismo , Epigênese Genética , Inativação Gênica , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 2/genética , Processamento de Proteína Pós-Traducional , Animais , Linhagem Celular , Cromatina/química , Retroalimentação Fisiológica , Histonas/genética , Histonas/metabolismo , Padrões de Herança , Camundongos , Mitose , Células-Tronco Embrionárias Murinas/citologia , Células-Tronco Embrionárias Murinas/metabolismo , Complexo Repressor Polycomb 1/metabolismo , Complexo Repressor Polycomb 2/metabolismo , Transcrição Genética
8.
Yi Chuan ; 41(4): 271-284, 2019 Apr 20.
Artigo em Chinês | MEDLINE | ID: mdl-30992249

RESUMO

Polycomb repressive complex 1 (PRC1) is a class of epigenetic regulatory complexes that normally represses gene expression by catalyzing and/or recognizing chromatin modifications. PRC1 mainly functions in stem cell maintenance, cell differentiation, cell cycle regulation and related processes. PRC1 also have aberrant functions which has been implicated in many types of developmental diseases and cancers. Mammalian PRC1 complexes are divided into six subtypes based on their composition and function; subtypes include PRC1.1 to PRC1.6. Each PRC1 subtype regulates a unique collection of target genes. The PRC1.6 complex subtype plays key roles in specifically repressing transcription of genes controlling germ cell development in embryonic stem cells and other somatic cell types. Recent research demonstrates that the PRC1.6 complex is also crucial for the timely activation of the germ line of specific genes during spermatogenesis, which is essential for proper gonad development. In this review, we summarize the identification of molecular functions of each core component of the PRC1.6 complex including how it recognizes and represses germ line specific genes. We also update the biological roles of this complex in regulating the spatiotemporal expression of germ line specific genes during embryonic development, gonad development, and spermatogenesis. Lastly, the crosstalk between the PRC1.6 complex and the other main epigenetic regulatory mechanisms involved in controlling spermatogenesis is discussed. Our discussion of the PRC1.6 complex in regulating germ line specific genes informs the studies of molecular processes of spermatogenesis and contributes to the understanding of the pathogenic mechanisms of male infertility.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Células Germinativas/crescimento & desenvolvimento , Complexo Repressor Polycomb 1/genética , Espermatogênese/genética , Animais , Diferenciação Celular , Células-Tronco Embrionárias/citologia , Epigênese Genética , Masculino , Análise Espaço-Temporal
9.
Mol Cell ; 74(5): 1020-1036.e8, 2019 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-31029541

RESUMO

The Polycomb system modifies chromatin and plays an essential role in repressing gene expression to control normal mammalian development. However, the components and mechanisms that define how Polycomb protein complexes achieve this remain enigmatic. Here, we use combinatorial genetic perturbation coupled with quantitative genomics to discover the central determinants of Polycomb-mediated gene repression in mouse embryonic stem cells. We demonstrate that canonical Polycomb repressive complex 1 (PRC1), which mediates higher-order chromatin structures, contributes little to gene repression. Instead, we uncover an unexpectedly high degree of synergy between variant PRC1 complexes, which is fundamental to gene repression. We further demonstrate that variant PRC1 complexes are responsible for distinct pools of H2A monoubiquitylation that are associated with repression of Polycomb target genes and silencing during X chromosome inactivation. Together, these discoveries reveal a new variant PRC1-dependent logic for Polycomb-mediated gene repression.


Assuntos
Cromatina/genética , Genômica , Complexo Repressor Polycomb 1/genética , Inativação do Cromossomo X/genética , Animais , Histonas/genética , Camundongos , Células-Tronco Embrionárias Murinas/metabolismo , Interferência de RNA , Ubiquitinação/genética
10.
Mol Cell ; 74(5): 1037-1052.e7, 2019 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-31029542

RESUMO

Polycomb repressive complexes 1 and 2 (PRC1 and PRC2) control cell identity by establishing facultative heterochromatin repressive domains at common sets of target genes. PRC1, which deposits H2Aub1 through the E3 ligases RING1A/B, forms six biochemically distinct subcomplexes depending on the assembled PCGF protein (PCGF1-PCGF6); however, it is yet unclear whether these subcomplexes have also specific activities. Here we show that PCGF1 and PCGF2 largely compensate for each other, while other PCGF proteins have high levels of specificity for distinct target genes. PCGF2 associates with transcription repression, whereas PCGF3 and PCGF6 associate with actively transcribed genes. Notably, PCGF3 and PCGF6 complexes can assemble and be recruited to several active sites independently of RING1A/B activity (therefore, of PRC1). For chromatin recruitment, the PCGF6 complex requires the combinatorial activities of its MGA-MAX and E2F6-DP1 subunits, while PCGF3 requires an interaction with the USF1 DNA binding transcription factor.


Assuntos
Complexo Repressor Polycomb 1/genética , Transcrição Genética , Ubiquitina-Proteína Ligases/genética , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Cromatina/genética , Proteínas de Ligação a DNA/genética , Fator de Transcrição E2F6/genética , Heterocromatina/genética , Camundongos , Células-Tronco Embrionárias Murinas/metabolismo , Complexo Repressor Polycomb 2/genética , Proteínas do Grupo Polycomb/genética , Proteínas Repressoras/genética , Fator de Transcrição DP1/genética , Fatores de Transcrição/genética , Fatores Estimuladores Upstream/genética
11.
Genet Test Mol Biomarkers ; 23(5): 348-352, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30990338

RESUMO

Background: As an essential member of the Polycomb group (PcG) proteins, chromobox homolog 7 (CBX7) is found deregulated in some human cancers, and is thought to be a contributing factor in carcinogenesis. However, the expression and role of CBX7 in hepatocellular carcinoma (HCC) is still not well characterized. Materials and Methods: The levels of the CBX7 protein were quantified in 75 paired HCC and adjacent nontumor tissues by immunohistochemistry; comparisons were made using McNemar's chi-square test. The Kaplan-Meier estimate was used for survival analysis. Results: We found that the expression of CBX7 in HCC tissues was significantly lower than that of adjacent nontumor tissues. In addition, decreased CBX7 expression levels were correlated with liver cirrhosis in HCC patients. Furthermore, the survival times of HCC patients who were CBX7-expression-negative were shorter than HCC patients who were CBX7-expression-positive. Conclusion: Our results show that downregulation of CBX7 is related to HCC progression and a poor prognosis in HCC patients.


Assuntos
Carcinoma Hepatocelular/genética , Neoplasias Hepáticas/genética , Complexo Repressor Polycomb 1/genética , Adulto , Idoso , Grupo com Ancestrais do Continente Asiático/genética , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Tumoral , China , Progressão da Doença , Regulação para Baixo , Feminino , Frequência do Gene , Predisposição Genética para Doença , Genótipo , Humanos , Estimativa de Kaplan-Meier , Neoplasias Hepáticas/metabolismo , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único/genética , Prognóstico
12.
Biochim Biophys Acta Gene Regul Mech ; 1862(4): 509-521, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30826432

RESUMO

The Chromobox protein homolog 7 (CBX7) belongs to the Polycomb Group (PcG) family, and, as part of the Polycomb repressive complex (PRC1), contributes to maintain transcriptional gene repression. Loss of CBX7 expression has been reported in several human malignant neoplasias, where it often correlates with an advanced cancer state and poor survival, proposing CBX7 as a candidate tumor-suppressor gene in cancer progression. Indeed, CBX7 is able to positively or negatively regulate the expression of genes involved in cell proliferation and cancer progression, such as E-cadherin, cyclin E, osteopontin, EGR1. To understand the molecular mechanisms that underlie the involvement of CBX7 in cancer progression, we designed a functional proteomic experiment based on CHIP-MS to identify novel CBX7 protein partners. Among the identified CBX7-interacting proteins we focused our attention on the Protein Arginine Methyltransferase 1 (PRMT1) whose critical role in epithelial-mesenchymal transition (EMT), cancer cell migration and invasion has been already reported. We confirmed the interaction between CBX7 and PRMT1 and demonstrated that this interaction is crucial for PRMT1 enzymatic activity both in vitro and in vivo and for the regulation of E-cadherin expression, an important hallmark of EMT. These results suggest a general mechanism by which CBX7 interacting with histone modification enzymes like HDAC2 and PRMT1 enhances E-cadherin expression. Therefore, disruption of this equilibrium may induce impairment of E-cadherin expression and increased cell migration eventually leading to EMT and, then, cancer progression.


Assuntos
Antígenos CD/genética , Caderinas/genética , Movimento Celular , Regulação da Expressão Gênica , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 1/metabolismo , Proteína-Arginina N-Metiltransferases/metabolismo , Proteínas Repressoras/metabolismo , Antígenos CD/metabolismo , Caderinas/metabolismo , Células HEK293 , Células HeLa , Histonas/metabolismo , Humanos , Metilação , Regiões Promotoras Genéticas
13.
Mol Cell ; 74(1): 101-117.e10, 2019 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-30827740

RESUMO

During X-inactivation, Xist RNA spreads along an entire chromosome to establish silencing. However, the mechanism and functional RNA elements involved in spreading remain undefined. By performing a comprehensive endogenous Xist deletion screen, we identify Repeat B as crucial for spreading Xist and maintaining Polycomb repressive complexes 1 and 2 (PRC1/PRC2) along the inactive X (Xi). Unexpectedly, spreading of these three factors is inextricably linked. Deleting Repeat B or its direct binding partner, HNRNPK, compromises recruitment of PRC1 and PRC2. In turn, ablating PRC1 or PRC2 impairs Xist spreading. Therefore, Xist and Polycomb complexes require each other to propagate along the Xi, suggesting a positive feedback mechanism between RNA initiator and protein effectors. Perturbing Xist/Polycomb spreading causes failure of de novo Xi silencing, with partial compensatory downregulation of the active X, and also disrupts topological Xi reconfiguration. Thus, Repeat B is a multifunctional element that integrates interdependent Xist/Polycomb spreading, silencing, and changes in chromosome architecture.


Assuntos
Fibroblastos/metabolismo , Deleção de Genes , Inativação Gênica , Células-Tronco Embrionárias Murinas/metabolismo , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 2/genética , RNA Longo não Codificante/genética , Inativação do Cromossomo X , Cromossomo X/genética , Animais , Linhagem Celular Transformada , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Masculino , Camundongos , Motivos de Nucleotídeos , Complexo Repressor Polycomb 1/metabolismo , Complexo Repressor Polycomb 2/metabolismo , Ligação Proteica , RNA Longo não Codificante/metabolismo , Sequências Repetitivas de Ácido Nucleico , Ribonucleoproteínas/genética , Ribonucleoproteínas/metabolismo , Cromossomo X/metabolismo
14.
Oncol Rep ; 41(4): 2575-2584, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30720120

RESUMO

Recently, emerging evidence shows that a number of long non­coding RNAs (lncRNAs) recruit polycomb group (PcG) proteins to specific chromatin loci to silence relevant gene expression. In the present study, we provided evidence that lncRNA candidates, selected by bioinformatic analysis and nervous system polycomb 1 (NSPc1), a key polycomb repressive complex 1 (PRC1) member, were highly expressed in glioma H4 cells in contrast to that noted in non­cancerous cells. RNA binding protein immunoprecipitation (RIP) assays demonstrated that metastasis associated lung adenocarcinoma transcript 1 (MALAT1), SOX2 overlapping transcript (SOX2OT) and maternally expressed 3 (MEG3) among the 8 candidates bound to the NSPc1 protein complex in glioma H4 cells. Furthermore, overexpression of NSPc1 caused a decrease in the expression of MALAT1 and MEG3 and increased expression of SOX2OT, while NSPc1 downregulation caused the levels of all three genes to increase. Meanwhile, suppression of the expression of MALAT1 increased the expression levels of mRNA and protein of NSPc1, whereas downregulation of the expression of SOX2OT decreased NSPc1 expression. Moreover, a significant decrease in cell growth and increased cell apoptosis were observed in the transfected H4 cells by MTT assay and flow cytometric analysis. The results showed that the reduced co­expression between NSPc1 and MALAT1/SOX2OT decreased the proliferation and promoted the death of H4 cells more obviously than the respectively decrease in expression of NSPc1, MALAT1 and SOX2OT. Remarkably, the influence of a simultaneously decreased expression of NSPc1 and SOX2OT on promoting cell apoptosis was more obvious than the total effect of the separate downregulation of NSPc1 and SOX2OT on accelerating cell death. However, that impact was partially counteracted in the silencing of the co­expression of MALAT1 and NSPc1. Furthermore, they cooperated to affect transcription of p21 and OCT4.Briefly, these data suggest NSPc1 polycomb protein complex binding and cross­talk to lncRNAs in glioma H4 cells, offering new insight into the important function of polycomb protein complex and lncRNA interactions in glioma cells and provide a novel view of potential biomarkers and targets for the diagnosis and therapy of glioma.


Assuntos
Regulação Neoplásica da Expressão Gênica , Glioma/genética , Complexo Repressor Polycomb 1/metabolismo , RNA Longo não Codificante/metabolismo , Apoptose/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Regulação para Baixo , Glioma/patologia , Humanos , Complexo Repressor Polycomb 1/genética , RNA Longo não Codificante/genética , RNA Interferente Pequeno/metabolismo
15.
Mol Cell ; 73(5): 930-945.e4, 2019 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-30709709

RESUMO

R-loops are three-stranded nucleic acid structures that form during transcription, especially over unmethylated CpG-rich promoters of active genes. In mouse embryonic stem cells (mESCs), CpG-rich developmental regulator genes are repressed by the Polycomb complexes PRC1 and PRC2. Here, we show that R-loops form at a subset of Polycomb target genes, and we investigate their contribution to Polycomb repression. At R-loop-positive genes, R-loop removal leads to decreased PRC1 and PRC2 recruitment and Pol II activation into a productive elongation state, accompanied by gene derepression at nascent and processed transcript levels. Stable removal of PRC2 derepresses R-loop-negative genes, as expected, but does not affect R-loops, PRC1 recruitment, or transcriptional repression of R-loop-positive genes. Our results highlight that Polycomb repression does not occur via one mechanism but consists of different layers of repression, some of which are gene specific. We uncover that one such mechanism is mediated by an interplay between R-loops and RING1B recruitment.


Assuntos
Ilhas de CpG , Regulação da Expressão Gênica no Desenvolvimento , Células-Tronco Embrionárias Murinas/fisiologia , Complexo Repressor Polycomb 1/metabolismo , Regiões Promotoras Genéticas , Transcrição Genética , Ubiquitina-Proteína Ligases/metabolismo , Animais , Sítios de Ligação , Linhagem Celular , Regulação para Baixo , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Camundongos , Células-Tronco Embrionárias Murinas/metabolismo , Conformação de Ácido Nucleico , Complexo Repressor Polycomb 1/genética , Ligação Proteica , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Relação Estrutura-Atividade , Ubiquitina-Proteína Ligases/genética
16.
Nat Commun ; 10(1): 442, 2019 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-30683859

RESUMO

MicroRNA deregulation is a consistent feature of glioblastoma, yet the biological effect of each single gene is generally modest, and therapeutically negligible. Here we describe a module of microRNAs, constituted by miR-124, miR-128 and miR-137, which are co-expressed during neuronal differentiation and simultaneously lost in gliomagenesis. Each one of these miRs targets several transcriptional regulators, including the oncogenic chromatin repressors EZH2, BMI1 and LSD1, which are functionally interdependent and involved in glioblastoma recurrence after therapeutic chemoradiation. Synchronizing the expression of these three microRNAs in a gene therapy approach displays significant anticancer synergism, abrogates this epigenetic-mediated, multi-protein tumor survival mechanism and results in a 5-fold increase in survival when combined with chemotherapy in murine glioblastoma models. These transgenic microRNA clusters display intercellular propagation in vivo, via extracellular vesicles, extending their biological effect throughout the whole tumor. Our results support the rationale and feasibility of combinatorial microRNA strategies for anticancer therapies.


Assuntos
Neoplasias Encefálicas/genética , Regulação Neoplásica da Expressão Gênica , Glioblastoma/genética , MicroRNAs/genética , Animais , Antineoplásicos Alquilantes/farmacologia , Neoplasias Encefálicas/mortalidade , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/terapia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/efeitos da radiação , Análise por Conglomerados , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Epigênese Genética , Vesículas Extracelulares/química , Vesículas Extracelulares/metabolismo , Feminino , Raios gama/uso terapêutico , Glioblastoma/mortalidade , Glioblastoma/patologia , Glioblastoma/terapia , Histona Desmetilases/genética , Histona Desmetilases/metabolismo , Humanos , Camundongos , Camundongos Nus , MicroRNAs/metabolismo , Neuroglia/efeitos dos fármacos , Neuroglia/metabolismo , Neuroglia/patologia , Neuroglia/efeitos da radiação , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 1/metabolismo , Análise de Sobrevida , Temozolomida/farmacologia , Ensaios Antitumorais Modelo de Xenoenxerto
17.
Nat Commun ; 10(1): 348, 2019 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-30664650

RESUMO

In Drosophila, a complex consisting of Calypso and ASX catalyzes H2A deubiquitination and has been reported to act as part of the Polycomb machinery in transcriptional silencing. The mammalian homologs of these proteins (BAP1 and ASXL1/2/3, respectively), are frequently mutated in various cancer types, yet their precise functions remain unclear. Using an integrative approach based on isogenic cell lines generated with CRISPR/Cas9, we uncover an unanticipated role for BAP1 in gene activation. This function requires the assembly of an enzymatically active BAP1-associated core complex (BAP1.com) containing one of the redundant ASXL proteins. We investigate the mechanism underlying BAP1.com-mediated transcriptional regulation and show that it does not participate in Polycomb-mediated silencing. Instead, our results establish that the function of BAP1.com is to safeguard transcriptionally active genes against silencing by the Polycomb Repressive Complex 1.


Assuntos
Linfócitos B/metabolismo , Proteínas de Ciclo Celular/genética , Histonas/metabolismo , Processamento de Proteína Pós-Traducional , Proteínas Supressoras de Tumor/genética , Ubiquitina Tiolesterase/genética , Animais , Linfócitos B/citologia , Sistemas CRISPR-Cas , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Drosophila melanogaster , Edição de Genes , Haploidia , Células HeLa , Histonas/genética , Humanos , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 1/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Células Sf9 , Spodoptera , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Ativação Transcricional , Proteínas Supressoras de Tumor/metabolismo , Ubiquitina Tiolesterase/metabolismo , Ubiquitinação
18.
Genes Dev ; 33(1-2): 55-60, 2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30567998

RESUMO

Polycomb-repressive complex 1 (PRC1) and PRC2 are critical chromatin regulators of gene expression and tissue development. Here, we show that despite extensive genomic cobinding, PRC1 is essential for epidermal integrity, whereas PRC2 is dispensable. Loss of PRC1 resulted in blistering skin, reminiscent of human skin fragility syndromes. Conversely, PRC1 does not restrict epidermal stratification during skin morphogenesis, whereas PRC2 does. Molecular dissection demonstrated that PRC1 functions with PRC2 to silence/dampen expression of adhesion genes. In contrast, PRC1 promotes expression of critical epidermal adhesion genes independently of PRC2-mediated H3K27me3. Together, we demonstrate a functional link between epigenetic regulation and skin diseases.


Assuntos
Células Epidérmicas/fisiologia , Epiderme/fisiologia , Epigênese Genética , Regulação da Expressão Gênica no Desenvolvimento/genética , Complexo Repressor Polycomb 1/metabolismo , Complexo Repressor Polycomb 2/metabolismo , Dermatopatias/genética , Animais , Adesão Celular/genética , Epiderme/crescimento & desenvolvimento , Histonas/metabolismo , Camundongos , Complexo Repressor Polycomb 1/genética , Dermatopatias/fisiopatologia
19.
Cell Physiol Biochem ; 50(1): 385-397, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30286469

RESUMO

BACKGROUND/AIMS: Melanoma is one of the most aggressive malignant tumors, with increasing incidence, poor prognosis, and lack of any effective targeted therapies. Abnormal expression of miR-29a has been found in several types of cancers, including melanoma. In this study, experiments were performed to investigate the role of miR-29a in melanoma, and the molecular mechanism by which miR-29a represses melanoma. METHODS: miR-29 and Bmi1 expression was examined by quantitative real-time polymerase chain reaction (qRT-PCR). The cell viability, apoptosis, migration and invasion were respectively determined by Cell Counting Kit-8 assay, Propidium iodide (PI) fluorescein isothiocynate (FITC)-Annexin V staining assay, wound healing assay and transwell assay. Luciferase reporter assay was performed to determine a target gene of miR-29a. Western blot was used to analyze protein expression of apoptosis-related proteins, Bmi1, Wnt/ß-catenin and Nuclear factor-κB (NF-κB) pathway target genes. RESULTS: miR-29a was down-regulated in all tested melanoma cell lines. Up-regulation of miR-29a effectively inhibited cell viability, migration, and invasion, but promoted apoptosis in A375 cells. Bmi1 was a direct target gene of miR-29a. Transfection with miR-29a mimic decreased cell migration and invasion and Bmi1 expression in Malme-3M cells, SK-MEL-2, SK-MEL-5, and M14 cell lines. Moreover, miR-29a might suppress growth, migration and invasion of A375 cells by negatively regulating Bmi1. In addition, our results demonstrated that transfection with miR-29a mimic effectively blocked Wnt/ß-catenin and NF-κB pathways via down-regulating Bmi1. CONCLUSION: miR-29a could be functioned as a potential tumor suppressor through direct regulation of Bmi1 in melanoma cells.


Assuntos
MicroRNAs/metabolismo , Complexo Repressor Polycomb 1/metabolismo , Regiões 3' não Traduzidas , Antagomirs/metabolismo , Apoptose , Sequência de Bases , Caspase 3/metabolismo , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Regulação para Baixo , Humanos , Melanoma , MicroRNAs/antagonistas & inibidores , MicroRNAs/genética , Complexo Repressor Polycomb 1/química , Complexo Repressor Polycomb 1/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Alinhamento de Sequência , Transdução de Sinais
20.
Gene ; 678: 302-311, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30096458

RESUMO

BMI-1 (B-lymphoma Mo-MLV insertion region 1) is a key protein partner in polycomb repressive complex 1 (PRC1) that helps in maintaining the integrity of the complex. It is also a key player in ubiquitination of histone H2A which affects gene expression pattern involved in various cellular processes such as cell proliferation, growth, DNA repair, apoptosis and senescence. In many cancers, Overexpression of BMI1correlates with advanced stages of disease, aggressive clinicopathological behavior, poor prognosis resistance to radiation and chemotherapy. BMI1 is emerging as a key player in EMT, chemo-resistance and cancer stemness. Overexpression is observed in various cancer types such as breast, primary hepatocellular carcinoma (HCC), gastric, ovarian, head and neck, pancreatic and lung cancer. Studies have shown that experimental reduction of BMI protein level in tumor cells results in inhibition of cell proliferation, induction of apoptosis and/or senescence, and increases susceptibility to cytotoxic agents and radiation therapy. Thus, inhibition of BMI1 expression particularly in breast cancer stem cells can be used as a potential strategy for the complete elimination of tumor and to prevent disease relapse. On other hand PTEN is known to be an important tumor suppressor next to p53. In many cancers particularly in breast cancer, p53 and PTEN undergo mutations. Studies have indicated the functional and mechanistic link between the BMI-1oncoprotein and tumor suppressor PTEN in the development and progression of cancer. The current review focuses on recent findings of how oncogenicity and chemo-resistance are caused by BMI1. It also highlights the transcriptional regulation between BMI1 and PTEN that dictates the therapeutic outcome in cancers where the functional p53 is absent. Herein, we have clearly demonstrated the regulation of transcription at genomic loci of BMI1 and PTEN in cancerous tissue or cells and the possible epigenetic regulation by histone deacetylase inhibitors (HDACi) at BMI1 and PTEN loci that may provide some clue for the possible therapy against TNBC in near future.


Assuntos
Neoplasias da Mama/genética , PTEN Fosfo-Hidrolase/genética , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 1/metabolismo , Neoplasias da Mama/metabolismo , Epigênese Genética/efeitos dos fármacos , Transição Epitelial-Mesenquimal , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Inibidores de Histona Desacetilases/farmacologia , Inibidores de Histona Desacetilases/uso terapêutico , Histonas/metabolismo , Humanos , Terapia de Alvo Molecular , Células-Tronco Neoplásicas/metabolismo , PTEN Fosfo-Hidrolase/metabolismo
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