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1.
Zhong Nan Da Xue Xue Bao Yi Xue Ban ; 44(5): 485-490, 2019 May 28.
Artigo em Chinês | MEDLINE | ID: mdl-31303610

RESUMO

OBJECTIVE: To explore the magnetic resonance imaging (MRI) characteristics of glioma with Brg/Brm-associated factor 53a (BAF53a) expression.
 Methods: A total of 121 patients with glioma was divided into a BAF53a high expression group (n=79) and a low expression group (n=42) according to the results of immunohistochemistry. Then the MRI characteristics, including lesion location, number, boundary, maximum diameter, peripheral edema, midline structure shift, homogeneity, cystic necrosis, hemorrhage, strengthening degree, ependymal strengthening, pia mater enhancement, deep white matter invasion and lesion across the midline (total 14 items), were analyzed.
 Results: The results showed that there were significance difference in lesion border, lesion edema, enhancement of the lesion, and deep white matter invasion between the 2 groups (all P<0.05).
 Conclusion: The MRI characteristics, such as lesion border, lesion edema degree, enhancement degree of the lesion and deep white matter invasion, might be associated with BAF53a expression in gliomas.


Assuntos
Actinas/metabolismo , Neoplasias Encefálicas , Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Ligação a DNA/metabolismo , Glioma , Humanos , Imagem por Ressonância Magnética , Necrose
2.
Yi Chuan ; 41(6): 509-523, 2019 Jun 20.
Artigo em Chinês | MEDLINE | ID: mdl-31257199

RESUMO

UDP-glucuronosyltransferases (UGTs) are an important family of phase 2 drug-metabolizing enzymes that catalyze the glucuronidation of numerous endogenous or exogenous small compounds. The aberrant expression of UGT isoforms causes many diseases, such as hyperbilirubinemia and affect drug efficacy or toxicity. Understanding mechanisms of UGT gene regulation will provide scientific foundations for disease prevention and personalized or precision medicine. Vertebrate UGT family genes can be divided into UGT1 and UGT2 subfamilies. Similar to the protocadherin, immunoglobulin, and T-cell receptor gene clusters and different from the UGT2 gene cluster, the UGT1 gene cluster is organized into variable and constant regions. The UGT1 variable region contains a tandem array of variable exons, each of which can be alternatively spliced to a single set of 4 downstream constant exons, generating at least nine UGT1 mRNAs that could be translated into different UGT1 glucuronyltransferase isoforms. Our previous work reveals that the relative orientations and locations of CTCF binding sites play a key role in the three-dimensional organization of the mammalian genomes in cell nuclei. Thus in order to study the transcriptional mechanisms of UGT1 gene cluster, the distributions and orientations of CTCF binding sites (CBSs) are analyzed and compared between human and mouse UGT1 gene clusters. We find that the CBSs in the UGT1 gene cluster are not conserved between human and mouse species. We show that CTCF and cohesin regulate the transcription of the UGT1 gene cluster by knocking down the CTCF or the cohesin subunit SMC3 in the human A549 cell line. By using CRISPR DNA-fragment editing, we deleted and inverted hCBS1. By RNA-seq experiments, we find that hCBS1 deletion results in a significant decrease of levels of the UGT1A6, UGT1A7, and UGT1A9 gene expression and that hCBS1 inversion results in a significant decrease of levels of the UGT1A7 gene expression. Our data suggest that the CTCF binding site hCBS1 plays an important regulatory role in the regulation of UGT1 gene expression, providing an experimental basis for further mechanistic studies of the 3D genome regulation of the UGT1 gene cluster.


Assuntos
Fator de Ligação a CCCTC/metabolismo , Regulação da Expressão Gênica , Glucuronosiltransferase/genética , Família Multigênica , Animais , Sítios de Ligação , Proteínas de Ciclo Celular/metabolismo , Cromatina , Proteínas Cromossômicas não Histona/metabolismo , Éxons , Humanos , Camundongos , RNA Mensageiro
3.
Nat Commun ; 10(1): 2908, 2019 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-31266948

RESUMO

Cohesin and CTCF are master regulators of genome topology. How these ubiquitous proteins contribute to cell-type specific genome structure is poorly understood. Here, we explore quantitative aspects of topologically associated domains (TAD) between pluripotent embryonic stem cells (ESC) and lineage-committed cells. ESCs exhibit permissive topological configurations which manifest themselves as increased inter- TAD interactions, weaker intra-TAD interactions, and a unique intra-TAD connectivity whereby one border makes pervasive interactions throughout the domain. Such 'stripe' domains are associated with both poised and active chromatin landscapes and transcription is not a key determinant of their structure. By tracking the developmental dynamics of stripe domains, we show that stripe formation is linked to the functional state of the cell through cohesin loading at lineage-specific enhancers and developmental control of CTCF binding site occupancy. We propose that the unique topological configuration of stripe domains represents a permissive landscape facilitating both productive and opportunistic gene regulation and is important for cellular identity.


Assuntos
Fator de Ligação a CCCTC/química , Fator de Ligação a CCCTC/metabolismo , Elementos Facilitadores Genéticos , Células-Tronco Pluripotentes/metabolismo , Fator de Ligação a CCCTC/genética , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Linhagem da Célula , Cromatina/química , Cromatina/genética , Cromatina/metabolismo , Proteínas Cromossômicas não Histona/química , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Células-Tronco Pluripotentes/química , Ligação Proteica , Domínios Proteicos , Especificidade da Espécie
4.
Nat Commun ; 10(1): 2950, 2019 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-31270318

RESUMO

X-chromosome inactivation triggers fusion of A/B compartments to inactive X (Xi)-specific structures known as S1 and S2 compartments. SMCHD1 then merges S1/S2s to form the Xi super-structure. Here, we ask how S1/S2 compartments form and reveal that Xist RNA drives their formation via recruitment of Polycomb repressive complex 1 (PRC1). Ablating Smchd1 in post-XCI cells unveils S1/S2 structures. Loss of SMCHD1 leads to trapping Xist in the S1 compartment, impairing RNA spreading into S2. On the other hand, depleting Xist, PRC1, or HNRNPK precludes re-emergence of S1/S2 structures, and loss of S1/S2 compartments paradoxically strengthens the partition between Xi megadomains. Finally, Xi-reactivation in post-XCI cells can be enhanced by depleting both SMCHD1 and DNA methylation. We conclude that Xist, PRC1, and SMCHD1 collaborate in an obligatory, sequential manner to partition, fuse, and direct self-association of Xi compartments required for proper spreading of Xist RNA.


Assuntos
Proteínas Cromossômicas não Histona/metabolismo , Cromossomos de Mamíferos/genética , Complexo Repressor Polycomb 1/metabolismo , RNA Longo não Codificante/metabolismo , Cromossomo X/química , Cromossomo X/genética , Animais , Metilação de DNA/genética , Histonas/metabolismo , Lisina/metabolismo , Camundongos , Modelos Genéticos , Inativação do Cromossomo X/genética
5.
Photochem Photobiol Sci ; 18(7): 1685-1699, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31166333

RESUMO

The UVR8 photoreceptor in Arabidopsis thaliana is specific for ultraviolet-B (UV-B; 280-315 nm) radiation and its activation leads to a number of UV-B acclimation responses, including the accumulation of flavonoids. UVR8 participates in a signaling cascade involving COP1 and HY5 so that the absence of any of these components results in a reduction in the ability of a plant to accumulate flavonoids in response to UV; Cop1 mutants show high dropouts and hy5-ks50 hyh double mutants show very low levels of flavonoids. The predominant phenolics in Arabidopsis thaliana are sinapic acid derivatives as well as non-aclyated quercetin and kaempferol di- and triglycosides containing glucose and rhamnose as glycosylated sugar moieties. How this flavonoid profile in Arabidopsis thaliana is affected by UV radiation, how rapidly these changes occur in changing UV conditions, and which components of the UV-B signalling pathway are involved in rapid UV acclimatization reactions is poorly understood. In the present study, we examined these questions by characterizing the flavonoid profiles of Arabidopsis thaliana signalling mutants and wild types grown under different UV levels of constant UV-B+PAR ratios and then transferring a subset of plants to alternate UV conditions. Results indicate that flavonoid accumulation in Arabidopsis thaliana is triggered by UV and this response is amplified by higher levels of UV but not by all compounds to the same extent. The catechol structure in quercetin seems to be less important than the glycosylation pattern, e.g. having 2 rhamnose moieties in determining responsivity. At low UV+PAR intensities the introduction of UV leads to an initial tendency of increase of flavonoids in the wild types that was detected after 3 days. It took 7 days for these changes to be detected in plants grown under high UV+PAR intensities suggesting a priming of PAR. Thus, the flavonoid profile in Arabidopsis thaliana is altered over time following exposure to UV and PAR, but the functional significance of these changes is currently unclear.


Assuntos
Arabidopsis/efeitos da radiação , Flavonoides/metabolismo , Transdução de Sinais/efeitos da radiação , Raios Ultravioleta , Arabidopsis/química , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Cromatografia Líquida de Alta Pressão , Proteínas Cromossômicas não Histona/metabolismo , Flavonoides/análise , Mutagênese , Folhas de Planta/química , Folhas de Planta/metabolismo , Folhas de Planta/efeitos da radiação , Espectrometria de Massas por Ionização por Electrospray , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo
6.
Photochem Photobiol Sci ; 18(7): 1675-1684, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31218318

RESUMO

UV-B exposure of plants regulates expression of numerous genes concerned with various responses. Sudden exposure of non-acclimated plants to high fluence rate, short wavelength UV-B induces expression via stress-related signaling pathways that are not specific to the UV-B stimulus, whereas low fluence rates of UV-B can regulate expression via the UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8). However, there is little information about whether non-stressful, low fluence rate UV-B treatments can activate gene expression independently of UVR8. Here, transcriptomic analysis of wild-type and uvr8 mutant Arabidopsis exposed to low fluence rate UV-B showed that numerous genes were regulated independently of UVR8. Moreover, nearly all of these genes were distinct to those induced by stress treatments. A small number of genes were expressed at all UV-B fluence rates employed and may be concerned with activation of eustress responses that facilitate acclimation to changing conditions. Expression of the gene encoding the transcription factor ARABIDOPSIS NAC DOMAIN CONTAINING PROTEIN 13 (ANAC13) was studied to characterise a low fluence rate, UVR8-independent response. ANAC13 is induced by as little as 0.1 µmol m-2 s-1 UV-B and its regulation is independent of components of the canonical UVR8 signaling pathway COP1 and HY5/HYH. Furthermore, UV-B induced expression of ANAC13 is independent of the photoreceptors CRY1, CRY2, PHOT1 and PHOT2 and phytochromes A, B, D and E. ANAC13 expression is induced over a range of UV-B wavelengths at low doses, with maximum response at 310 nm. This study provides a basis for further investigation of UVR8 and stress independent, low fluence rate UV-B signaling pathway(s).


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Raios Ultravioleta , Proteínas de Arabidopsis/genética , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Proteínas Cromossômicas não Histona/genética , Criptocromos/genética , Criptocromos/metabolismo , Transdução de Sinais/efeitos da radiação , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo
7.
Nat Commun ; 10(1): 2343, 2019 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-31138803

RESUMO

Despite the conserved essential function of centromeres, centromeric DNA itself is not conserved. The histone-H3 variant, CENP-A, is the epigenetic mark that specifies centromere identity. Paradoxically, CENP-A normally assembles on particular sequences at specific genomic locations. To gain insight into the specification of complex centromeres, here we take an evolutionary approach, fully assembling genomes and centromeres of related fission yeasts. Centromere domain organization, but not sequence, is conserved between Schizosaccharomyces pombe, S. octosporus and S. cryophilus with a central CENP-ACnp1 domain flanked by heterochromatic outer-repeat regions. Conserved syntenic clusters of tRNA genes and 5S rRNA genes occur across the centromeres of S. octosporus and S. cryophilus, suggesting conserved function. Interestingly, nonhomologous centromere central-core sequences from S. octosporus and S. cryophilus are recognized in S. pombe, resulting in cross-species establishment of CENP-ACnp1 chromatin and functional kinetochores. Therefore, despite the lack of sequence conservation, Schizosaccharomyces centromere DNA possesses intrinsic conserved properties that promote assembly of CENP-A chromatin.


Assuntos
Centrômero/genética , Montagem e Desmontagem da Cromatina/genética , Cromatina/metabolismo , Proteínas Cromossômicas não Histona/genética , DNA/metabolismo , Proteínas de Schizosaccharomyces pombe/genética , Schizosaccharomyces/genética , Centrômero/metabolismo , Proteína Centromérica A/genética , Proteína Centromérica A/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Sequência Conservada , Epigênese Genética , Histonas , Cinetocoros , RNA Ribossômico 5S , RNA de Transferência , Proteínas de Schizosaccharomyces pombe/metabolismo , Sintenia
8.
Nat Commun ; 10(1): 2356, 2019 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-31142743

RESUMO

Centrosomes control cell motility, polarity and migration that is thought to be mediated by their microtubule-organizing capacity. Here we demonstrate that WNT signalling drives a distinct form of non-directional cell motility that requires a key centrosome module, but not microtubules or centrosomes. Upon exosome mobilization of PCP-proteins, we show that DVL2 orchestrates recruitment of a CEP192-PLK4/AURKB complex to the cell cortex where PLK4/AURKB act redundantly to drive protrusive activity and cell motility. This is mediated by coordination of formin-dependent actin remodelling through displacement of cortically localized DAAM1 for DAAM2. Furthermore, abnormal expression of PLK4, AURKB and DAAM1 is associated with poor outcomes in breast and bladder cancers. Thus, a centrosomal module plays an atypical function in WNT signalling and actin nucleation that is critical for cancer cell motility and is associated with more aggressive cancers. These studies have broad implications in how contextual signalling controls distinct modes of cell migration.


Assuntos
Aurora Quinase B/metabolismo , Movimento Celular , Centrossomo/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Proteínas Desgrenhadas/metabolismo , Neoplasias/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Via de Sinalização Wnt , Actinas/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Neoplasias da Mama/metabolismo , Carcinoma de Células de Transição/metabolismo , Linhagem Celular Tumoral , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas dos Microfilamentos/metabolismo , Prognóstico , Mapas de Interação de Proteínas , Reação em Cadeia da Polimerase em Tempo Real , Neoplasias da Bexiga Urinária/metabolismo
9.
Nat Neurosci ; 22(6): 875-886, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31061493

RESUMO

Misfolded protein toxicity and failure of protein quality control underlie neurodegenerative diseases including amyotrophic lateral sclerosis and frontotemporal dementia. Here, we identified Lethal(3)malignant brain tumor-like protein 1 (L3MBTL1) as a key regulator of protein quality control, the loss of which protected against the proteotoxicity of mutant Cu/Zn superoxide dismutase or C9orf72 dipeptide repeat proteins. L3MBTL1 acts by regulating p53-dependent quality control systems that degrade misfolded proteins. SET domain-containing protein 8, an L3MBTL1-associated p53-binding protein, also regulated clearance of misfolded proteins and was increased by proteotoxicity-associated stresses in mammalian cells. Both L3MBTL1 and SET domain-containing protein 8 were upregulated in the central nervous systems of mouse models of amyotrophic lateral sclerosis and human patients with amyotrophic lateral sclerosis/frontotemporal dementia. The role of L3MBTL1 in protein quality control is conserved from Caenorhabditis elegans to mammalian neurons. These results reveal a protein quality-control pathway that operates in both normal stress response and proteotoxicity-associated neurodegenerative diseases.


Assuntos
Esclerose Amiotrófica Lateral/metabolismo , Esclerose Amiotrófica Lateral/patologia , Proteínas Cromossômicas não Histona/metabolismo , Demência Frontotemporal/metabolismo , Demência Frontotemporal/patologia , Degeneração Neural/metabolismo , Degeneração Neural/patologia , Animais , Caenorhabditis elegans , Drosophila , Humanos , Camundongos , Neurônios/metabolismo , Neurônios/patologia
10.
Life Sci ; 229: 225-232, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31085244

RESUMO

AIMS: Cellular senescence is a well-known cancer prevention mechanism, inducing cancer cells to senescence can enhance cancer immunotherapy. However, how cellular senescence is regulated is not fully understood. Dynamic chromatin changes have been discovered during cellular senescence, while the causality remains elusive. BAZ1A, a gene coding the accessory subunit of ATP-dependent chromatin remodeling complex, showed decreased expression in multiple cellular senescence models. We aim to investigate the functional role of BAZ1A in regulating senescence in cancer and normal cells. MATERIALS AND METHODS: Knockdown of BAZ1A was performed via lentivirus mediated short hairpin RNA (shRNA) in various cancer cell lines (A549 and U2OS) and normal cells (HUVEC, NIH3T3 and MEF). A series of senescence-associated phenotypes were quantified by CCK-8 assay, SA-ß-Gal staining and EdU incorporation assay, etc. KEY FINDINGS: Knockdown (KD) of BAZ1A induced series of senescence-associated phenotypes in both cancer and normal cells. BAZ1A-KD caused the upregulated expression of SMAD3, which in turn activated the transcription of p21 coding gene CDKN1A and resulted in senescence-associated phenotypes in human cancer cells (A549 and U2OS). SIGNIFICANCE: Our results revealed chromatin remodeling modulator BAZ1A acting as a novel regulator of cellular senescence in both normal and cancer cells, indicating a new target for potential cancer treatment.


Assuntos
Neoplasias Ósseas/patologia , Senescência Celular , Montagem e Desmontagem da Cromatina , Proteínas Cromossômicas não Histona/metabolismo , Osteossarcoma/patologia , Fatores de Transcrição/metabolismo , Células A549 , Animais , Neoplasias Ósseas/genética , Neoplasias Ósseas/metabolismo , Células Cultivadas , Proteínas Cromossômicas não Histona/genética , Fibroblastos/citologia , Fibroblastos/metabolismo , Células Endoteliais da Veia Umbilical Humana , Humanos , Camundongos , Células NIH 3T3 , Osteossarcoma/genética , Osteossarcoma/metabolismo , Transdução de Sinais , Fatores de Transcrição/genética
11.
Nat Commun ; 10(1): 2133, 2019 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-31086177

RESUMO

Polycomb (PcG) and Trithorax (TrxG) group proteins give stable epigenetic memory of silent and active gene expression states, but also allow poised states in pluripotent cells. Here we systematically address the relationship between poised, active and silent chromatin, by integrating 73 publications on PcG/TrxG biochemistry into a mathematical model comprising 144 nucleosome modification states and 8 enzymatic reactions. Our model predicts that poised chromatin is bistable and not bivalent. Bivalent chromatin, containing opposing active and silent modifications, is present as an unstable background population in all system states, and different subtypes co-occur with active and silent chromatin. In contrast, bistability, in which the system switches frequently between stable active and silent states, occurs under a wide range of conditions at the transition between monostable active and silent system states. By proposing that bistability and not bivalency is associated with poised chromatin, this work has implications for understanding the molecular nature of pluripotency.


Assuntos
Cromatina/metabolismo , Epigênese Genética/fisiologia , Modelos Biológicos , Proteínas do Grupo Polycomb/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Drosophila/metabolismo , Enzimas/metabolismo , Código das Histonas/fisiologia , Histona-Lisina N-Metiltransferase/metabolismo , Histonas/metabolismo , Proteína de Leucina Linfoide-Mieloide/metabolismo , Nucleossomos/metabolismo
12.
Genes Dev ; 33(15-16): 936-959, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31123059

RESUMO

Changes in chromatin structure mediated by ATP-dependent nucleosome remodelers and histone modifying enzymes are integral to the process of gene regulation. Here, we review the roles of the SWI/SNF (switch/sucrose nonfermenting) and NuRD (nucleosome remodeling and deacetylase) and the Polycomb system in chromatin regulation and cancer. First, we discuss the basic molecular mechanism of nucleosome remodeling, and how this controls gene transcription. Next, we provide an overview of the functional organization and biochemical activities of SWI/SNF, NuRD, and Polycomb complexes. We describe how, in metazoans, the balance of these activities is central to the proper regulation of gene expression and cellular identity during development. Whereas SWI/SNF counteracts Polycomb, NuRD facilitates Polycomb repression on chromatin. Finally, we discuss how disruptions of this regulatory equilibrium contribute to oncogenesis, and how new insights into the biological functions of remodelers and Polycombs are opening avenues for therapeutic interventions on a broad range of cancer types.


Assuntos
Montagem e Desmontagem da Cromatina/genética , Proteínas Cromossômicas não Histona/metabolismo , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/metabolismo , Neoplasias/fisiopatologia , Proteínas do Grupo Polycomb/metabolismo , Fatores de Transcrição/metabolismo , Animais , Regulação da Expressão Gênica no Desenvolvimento , Humanos
13.
Nat Commun ; 10(1): 2194, 2019 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-31097704

RESUMO

Although the physical properties of chromosomes, including their morphology, mechanics, and dynamics are crucial for their biological function, many basic questions remain unresolved. Here we directly image the circular chromosome in live E. coli with a broadened cell shape. We find that it exhibits a torus topology with, on average, a lower-density origin of replication and an ultrathin flexible string of DNA at the terminus of replication. At the single-cell level, the torus is strikingly heterogeneous, with blob-like Mbp-size domains that undergo major dynamic rearrangements, splitting and merging at a minute timescale. Our data show a domain organization underlying the chromosome structure of E. coli, where MatP proteins induce site-specific persistent domain boundaries at Ori/Ter, while transcription regulators HU and Fis induce weaker transient domain boundaries throughout the genome. These findings provide an architectural basis for the understanding of the dynamic spatial organization of bacterial genomes in live cells.


Assuntos
Cromossomos Bacterianos/química , DNA Bacteriano/química , DNA Circular/química , Escherichia coli/genética , Genoma Bacteriano , Proteínas Cromossômicas não Histona/metabolismo , Cromossomos Bacterianos/metabolismo , Replicação do DNA , DNA Bacteriano/metabolismo , DNA Circular/metabolismo , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Microscopia Intravital/instrumentação , Microscopia Intravital/métodos , Microscopia de Fluorescência/instrumentação , Microscopia de Fluorescência/métodos , Conformação de Ácido Nucleico , Análise de Célula Única/instrumentação , Análise de Célula Única/métodos
14.
Nat Commun ; 10(1): 2110, 2019 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-31068593

RESUMO

Ribosome biogenesis is a canonical hallmark of cell growth and proliferation. Here we show that execution of Epithelial-to-Mesenchymal Transition (EMT), a migratory cellular program associated with development and tumor metastasis, is fueled by upregulation of ribosome biogenesis during G1/S arrest. This unexpected EMT feature is independent of species and initiating signal, and is accompanied by release of the repressive nucleolar chromatin remodeling complex (NoRC) from rDNA, together with recruitment of the EMT-driving transcription factor Snai1 (Snail1), RNA Polymerase I (Pol I) and the Upstream Binding Factor (UBF). EMT-associated ribosome biogenesis is also coincident with increased nucleolar recruitment of Rictor, an essential component of the EMT-promoting mammalian target of rapamycin complex 2 (mTORC2). Inhibition of rRNA synthesis in vivo differentiates primary tumors to a benign, Estrogen Receptor-alpha (ERα) positive, Rictor-negative phenotype and reduces metastasis. These findings implicate the EMT-associated ribosome biogenesis program with cellular plasticity, de-differentiation, cancer progression and metastatic disease.


Assuntos
Transição Epitelial-Mesenquimal/fisiologia , Pontos de Checagem da Fase G1 do Ciclo Celular/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Regulação Neoplásica da Expressão Gênica , Ribossomos/metabolismo , Animais , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Diferenciação Celular/fisiologia , Linhagem Celular Tumoral/transplante , Movimento Celular/fisiologia , Nucléolo Celular/metabolismo , Embrião de Galinha , Proteínas Cromossômicas não Histona/metabolismo , DNA Ribossômico/metabolismo , Modelos Animais de Doenças , Feminino , Perfilação da Expressão Gênica , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , RNA Ribossômico/metabolismo , Ribossomos/genética
15.
Pharmazie ; 74(3): 154-156, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30961681

RESUMO

MicroRNAs (miRs) are crucial regulators for tumorigenesis through negatively regulating their target genes expression in the manner of 3'-untranslated region (3'-UTR) binding. MiR-205-5p has been reported to function as a tumor suppressor in several cancer types. The aim of this study was to investigate the role of miR-205-5p/chromobox homolog 1 (CBX1) axis in human pituitary tumors. The expression of miR-205-5p was firstly examined by quantitative real-time PCR and the results revealed that miR-205-5p expression was declined in pituitary cell lines compared with normal cell line. Overexpression of miR-205-5p effectively decreased cell proliferation and cell migration. Based on the results of bioinformatic analysis, luciferase reporter assay, and western blot, we identified CBX1 as a direct target of miR-205-5p. Notably, overexpression of CBX1 promoted cell proliferation and migration. The effects of miR-205-5p overexpression on cell proliferation and migration can be reversed by CBX1 overexpression. Based on these findings, we deducted that miR-205-5p inhibits the cell proliferation and migration through directly targeting CBX1.


Assuntos
Proteínas Cromossômicas não Histona/genética , MicroRNAs/genética , Neoplasias Hipofisárias/genética , Apoptose/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Proteínas Cromossômicas não Histona/biossíntese , Proteínas Cromossômicas não Histona/metabolismo , Progressão da Doença , Regulação para Baixo , Células HEK293 , Humanos , MicroRNAs/biossíntese , MicroRNAs/metabolismo , Neoplasias Hipofisárias/metabolismo , Neoplasias Hipofisárias/patologia
16.
Nat Commun ; 10(1): 1673, 2019 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-30975984

RESUMO

Accurate chromosome segregation relies on microtubule end conversion, the ill-understood ability of kinetochores to transit from lateral microtubule attachment to durable association with dynamic microtubule plus-ends. The molecular requirements for this conversion and the underlying biophysical mechanisms are elusive. We reconstituted end conversion in vitro using two kinetochore components: the plus end-directed kinesin CENP-E and microtubule-binding Ndc80 complex, combined on the surface of a microbead. The primary role of CENP-E is to ensure close proximity between Ndc80 complexes and the microtubule plus-end, whereas Ndc80 complexes provide lasting microtubule association by diffusing on the microtubule wall near its tip. Together, these proteins mediate robust plus-end coupling during several rounds of microtubule dynamics, in the absence of any specialized tip-binding or regulatory proteins. Using a Brownian dynamics model, we show that end conversion is an emergent property of multimolecular ensembles of microtubule wall-binding proteins with finely tuned force-dependent motility characteristics.


Assuntos
Segregação de Cromossomos , Cinesina/metabolismo , Cinetocoros/metabolismo , Microtúbulos/metabolismo , Animais , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/isolamento & purificação , Proteínas Cromossômicas não Histona/metabolismo , Microscopia de Fluorescência , Modelos Biológicos , Dinâmica não Linear , Proteínas Nucleares/genética , Proteínas Nucleares/isolamento & purificação , Proteínas Nucleares/metabolismo , Ligação Proteica , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Células Sf9 , Imagem Individual de Molécula , Processos Estocásticos , Proteínas de Xenopus/genética , Proteínas de Xenopus/isolamento & purificação , Proteínas de Xenopus/metabolismo
17.
Nat Commun ; 10(1): 1720, 2019 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-30979890

RESUMO

ATP-dependent chromatin remodelling enzymes (remodellers) regulate DNA accessibility in eukaryotic genomes. Many remodellers reposition (slide) nucleosomes, however, how DNA is propagated around the histone octamer during this process is unclear. Here we examine the real-time coordination of remodeller-induced DNA movements on both sides of the nucleosome using three-colour single-molecule FRET. During sliding by Chd1 and SNF2h remodellers, DNA is shifted discontinuously, with movement of entry-side DNA preceding that of exit-side DNA. The temporal delay between these movements implies a single rate-limiting step dependent on ATP binding and transient absorption or buffering of at least one base pair. High-resolution cross-linking experiments show that sliding can be achieved by buffering as few as 3 bp between entry and exit sides of the nucleosome. We propose that DNA buffering ensures nucleosome stability during ATP-dependent remodelling, and provides a means for communication between remodellers acting on opposite sides of the nucleosome.


Assuntos
Adenosina Trifosfatases/metabolismo , Cromatina/química , Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Ligação a DNA/metabolismo , DNA/análise , Nucleossomos/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Trifosfato de Adenosina/química , Animais , Tampões (Química) , DNA Helicases/química , Transferência Ressonante de Energia de Fluorescência , Histonas/química , Humanos , Ligação Proteica , Saccharomyces cerevisiae/metabolismo , Xenopus
18.
J Plant Physiol ; 236: 105-108, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30947026

RESUMO

SSRP1 is a subunit of the histone chaperone FACT that associates with elongating RNA polymerase II (RNAPII) along the transcribed region of genes. FACT facilitates transcriptional elongation by destabilising nucleosomes in the path of RNAPII, assisting efficient transcription of chromatin templates. In contrast to wild type seeds, freshly harvested seeds of the Arabidopsis ssrp1 mutant germinate efficiently, exhibiting reduced seed dormancy. In line with this phenotype, the ssrp1 seeds have decreased transcript levels of the DOG1 gene, which is a known quantitative trait locus (QTL) for seed dormancy. Analysis of ssrp1 plants harbouring an additional copy of DOG1 show increased levels of DOG1 transcript and consistently more robust seed dormancy. Therefore, our findings indicate that SSRP1 is a novel factor required for the efficient expression of DOG1 and hence a modulator of seed dormancy in Arabidopsis.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/fisiologia , Proteínas Cromossômicas não Histona/fisiologia , Chaperonas de Histonas/fisiologia , Dormência de Plantas , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Germinação , Chaperonas de Histonas/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa
19.
Essays Biochem ; 63(1): 157-165, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-30940740

RESUMO

Orchestrating vertebrate genomes require a complex interplay between the linear composition of the genome and its 3D organization inside the nucleus. This requires the function of specialized proteins, able to tune various aspects of genome organization and gene regulation. The CCCTC-binding factor (CTCF) is a DNA binding factor capable of regulating not only the 3D genome organization, but also key aspects of gene expression, including transcription activation and repression, RNA splicing, and enhancer/promoter insulation. A growing body of evidence proposes that CTCF, together with cohesin contributes to DNA loop formation and 3D genome organization. CTCF binding sites are mutation hotspots in cancer, while mutations in CTCF itself lead to intellectual disabilities, emphasizing its importance in disease etiology. In this review we cover various aspects of CTCF function, revealing the polyvalence of this factor as a highly diversified tool for vertebrate genome organization and transcription regulation.


Assuntos
Fator de Ligação a CCCTC/genética , Cromatina/genética , Regulação da Expressão Gênica , Genoma , Animais , Fator de Ligação a CCCTC/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Cromatina/metabolismo , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , DNA/genética , DNA/metabolismo , Humanos , Mutação , RNA/genética , RNA/metabolismo
20.
Essays Biochem ; 63(1): 167-176, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-31015387

RESUMO

In the nuclei of eukaryotic cells, the genetic information is organized at several levels. First, the DNA is wound around the histone proteins, to form a structure termed as chromatin fiber. This fiber is then arranged into chromatin loops that can cluster together and form higher order structures. This packaging of chromatin provides on one side compaction but also functional compartmentalization. The cohesin complex is a multifunctional ring-shaped multiprotein complex that organizes the chromatin fiber to establish functional domains important for transcriptional regulation, help with DNA damage repair, and ascertain stable inheritance of the genome during cell division. Our current model for cohesin function suggests that cohesin tethers chromatin strands by topologically entrapping them within its ring. To achieve this, cohesin's association with chromatin needs to be very precisely regulated in timing and position on the chromatin strand. Here we will review the current insight in when and where cohesin associates with chromatin and which factors regulate this. Further, we will discuss the latest insights into where and how the cohesin ring opens to embrace chromatin and also the current knowledge about the 'exit gates' when cohesin is released from chromatin.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Cromatina/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Animais , DNA/metabolismo , Humanos , Plantas , Ligação Proteica , Leveduras
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