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1.
FASEB J ; 35(9): e21814, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34369624

RESUMO

Alteration in glucose homeostasis during cancer metabolism is an important phenomenon. Though several important transcription factors have been well studied in the context of the regulation of metabolic gene expression, the role of epigenetic readers in this regard remains still elusive. Epigenetic reader protein transcription factor 19 (TCF19) has been recently identified as a novel glucose and insulin-responsive factor that modulates histone posttranslational modifications to regulate glucose homeostasis in hepatocytes. Here we report that TCF19 interacts with a non-histone, well-known tumor suppressor protein 53 (p53) and co-regulates a wide array of metabolic genes. Among these, the p53-responsive carbohydrate metabolic genes Tp53-induced glycolysis and apoptosis regulator (TIGAR) and Cytochrome C Oxidase assembly protein 2 (SCO2), which are the key regulators of glycolysis and oxidative phosphorylation respectively, are under direct regulation of TCF19. Remarkably, TCF19 can form different transcription activation/repression complexes which show substantial overlap with that of p53, depending on glucose-mediated variant stress situations as obtained from IP/MS studies. Interestingly, we observed that TCF19/p53 complexes either have CBP or HDAC1 to epigenetically program the expression of TIGAR and SCO2 genes depending on short-term high glucose or prolonged high glucose conditions. TCF19 or p53 knockdown significantly altered the cellular lactate production and led to increased extracellular acidification rate. Similarly, OCR and cellular ATP production were reduced and mitochondrial membrane potential was compromised upon depletion of TCF19 or p53. Subsequently, through RNA-Seq analysis from patients with hepatocellular carcinoma, we observed that TCF19/p53-mediated metabolic regulation is fundamental for sustenance of cancer cells. Together the study proposes that TCF19/p53 complexes can regulate metabolic gene expression programs responsible for mitochondrial energy homeostasis and stress adaptation.


Assuntos
Proteínas Reguladoras de Apoptose/genética , Carcinoma Hepatocelular/genética , Neoplasias Hepáticas/genética , Mitocôndrias/genética , Chaperonas Moleculares/genética , Monoéster Fosfórico Hidrolases/genética , Fatores de Transcrição/genética , Transcrição Genética/genética , Proteína Supressora de Tumor p53/genética , Adaptação Biológica/genética , Apoptose/genética , Linhagem Celular Tumoral , Metabolismo Energético/genética , Glucose/genética , Células Hep G2 , Homeostase/genética , Humanos , Potencial da Membrana Mitocondrial/genética , Estresse Fisiológico/genética , Ativação Transcricional/genética
2.
Mol Cancer Res ; 19(10): 1688-1698, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34158394

RESUMO

Poly(ADP-ribose) polymerase-1 (PARP-1) has gained considerable attention as a target for therapeutic inhibitors in breast cancers. Previously we showed that PARP-1 localizes to active gene promoters to regulate histone methylation and RNA polymerase II activity (Pol II), altering the expression of various tumor-related genes. Here we report a role for PARP-1 in estrogen-dependent transcription in estrogen receptor alpha (ERα)-positive (ER+) breast cancers. Global nuclear run-on and sequencing analyses functionally linked PARP-1 to the direct control of estrogen-regulated gene expression in ER+ MCF-7 breast cancer cells by promoting transcriptional elongation by Pol II. Furthermore, chromatin immunoprecipitation sequencing analyses revealed that PARP-1 regulates the estrogen-dependent binding of ERα and FoxA1 to a subset of genomic ERα binding sites, promoting active enhancer formation. Moreover, we found that the expression levels of the PARP-1- and estrogen-coregulated gene set are enriched in the luminal subtype of breast cancer, and high PARP-1 expression in ER+ cases correlates with poor survival. Finally, treatment with a PARP inhibitor or a transcriptional elongation inhibitor attenuated estrogen-dependent growth of multiple ER+ breast cancer cell lines. Taken together, our results show that PARP-1 regulates critical molecular pathways that control the estrogen-dependent gene expression program underlying the proliferation of ER+ breast cancer cells. IMPLICATIONS: PARP-1 regulates the estrogen-dependent genomic binding of ERα and FoxA1 to regulate critical gene expression programs by RNA Pol II that underlie the proliferation of ER+ breast cancers, providing a potential therapeutic opportunity for PARP inhibitors in estrogen-responsive breast cancers.

3.
Cancer Res ; 81(16): 4174-4182, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-34016622

RESUMO

Despite extensive progress in developing anticancer therapies, therapy resistance remains a major challenge that promotes disease relapse. The changes that lead to therapy resistance can be intrinsically present or may be initiated during treatment. Genetic and epigenetic heterogeneity in tumors make it more challenging to deal with therapy resistance. Recent advances in genome-wide analyses have revealed that the deregulation of distal gene regulatory elements, such as enhancers, appears in several pathophysiological conditions, including cancer. Beyond the conventional function of enhancers in recruiting transcription factors to gene promoters, enhancer elements are also transcribed into noncoding RNAs known as enhancer RNAs (eRNA). Accumulating evidence suggests that uncontrolled enhancer activity with aberrant eRNA expression promotes oncogenesis. Interestingly, tissue-specific, transcribed eRNAs from active enhancers can serve as potential therapeutic targets or biomarkers in several cancer types. This review provides a comprehensive overview of the mechanisms of enhancer transcription and eRNAs as well as their potential roles in cancer and drug resistance.

4.
Cell Death Dis ; 11(12): 1073, 2020 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-33323928

RESUMO

The major challenge in chemotherapy lies in the gain of therapeutic resistance properties of cancer cells. The relatively small fraction of chemo-resistant cancer cells outgrows and are responsible for tumor relapse, with acquired invasiveness and stemness. We demonstrate that zinc-finger MYND type-8 (ZMYND8), a putative chromatin reader, suppresses stemness, drug resistance, and tumor-promoting genes, which are hallmarks of cancer. Reinstating ZMYND8 suppresses chemotherapeutic drug doxorubicin-induced tumorigenic potential (at a sublethal dose) and drug resistance, thereby resetting the transcriptional program of cells to the epithelial state. The ability of ZMYND8 to chemo-sensitize doxorubicin-treated metastatic breast cancer cells by downregulating tumor-associated genes was further confirmed by transcriptome analysis. Interestingly, we observed that ZMYND8 overexpression in doxorubicin-treated cells stimulated those involved in a good prognosis in breast cancer. Consistently, sensitizing the cancer cells with ZMYND8 followed by doxorubicin treatment led to tumor regression in vivo and revert back the phenotypes associated with drug resistance and stemness. Intriguingly, ZMYND8 modulates the bivalent or poised oncogenes through its association with KDM5C and EZH2, thereby chemo-sensitizing the cells to chemotherapy for better disease-free survival. Collectively, our findings indicate that poised chromatin is instrumental for the acquisition of chemo-resistance by cancer cells and propose ZMYND8 as a suitable epigenetic tool that can re-sensitize the chemo-refractory breast carcinoma.


Assuntos
Oncogenes , Proteínas Supressoras de Tumor/metabolismo , Animais , Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Carcinogênese/efeitos dos fármacos , Carcinogênese/genética , Carcinogênese/patologia , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Movimento Celular/genética , Regulação para Baixo/efeitos dos fármacos , Regulação para Baixo/genética , Doxorrubicina/farmacologia , Doxorrubicina/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Epigênese Genética/efeitos dos fármacos , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Transição Epitelial-Mesenquimal/genética , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Genoma Humano , Histona Desmetilases/metabolismo , Humanos , Camundongos Endogâmicos BALB C , Camundongos Nus , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Fenótipo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Resultado do Tratamento , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Neoplasias de Mama Triplo Negativas/genética , Neoplasias de Mama Triplo Negativas/patologia
5.
J Clin Med ; 9(8)2020 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823540

RESUMO

COVID-19 has catastrophically affected the world's panoramic view of human well-being in terms of healthcare and management. With the increase in the number of cases worldwide, neurological symptoms and psychological illnesses from COVID-19 have increasingly upsurged. Mental health illness and affective disorders, including depression, obsessive-compulsive disorder, anxiety, phobia, and panic disorders, are highly impacted due to social distress. The COVID-19 pandemic not only affected people with pre-existing mental and affective illnesses, but also healthy individuals with anxiety, worrying, and panic symptoms, and fear conditioning. In addditon, the novel coronavirus is known to impact the central nervous system in the brain, resulting in severe and certain long-lasting neurological issues. Owing to the significance of neurological and psychological events, the present perspective has been an attempt to disseminate the impact of COVID-19 on neural injury through inflammation, and its interrelation with psychological symptoms. In this current review, we synthesize the literature to highlight the critical associations between SARS-CoV-2 infection and the nervous system, and mental health illness, and discuss potential mechanisms of neural injury through psycho-neuroimmunity.

6.
Cancers (Basel) ; 12(6)2020 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-32532008

RESUMO

Hypoxanthine phosphoribosyl transferase 1 (HPRT1) is traditionally believed to be a housekeeping gene; however, recent reports suggest that it is upregulated in several cancers and is associated with clinical outcomes. HPRT1 is located on chromosome X and encodes the HPRT enzyme, which functions in recycling nucleotides to supply for DNA and RNA synthesis in actively dividing cells. Here, we used transcriptomic analyses to interrogate its expression across all known cancer types and elucidated its role in regulating gene expression in breast cancer. We observed elevated HPRT1 RNA levels in malignant tissues when compared to normal controls, indicating its potential as a diagnostic and prognostic marker. Further, in breast cancer, the subtype-specific analysis showed that its expression was highest in basal and triple-negative breast cancer, and HPRT1 knockdown in breast cancer cells suggested that HPRT1 positively regulates genes related to cancer pathways. Collectively, our results essentially highlight the importance of and change the way in which HPRT1's function is studied in biology, warranting careful examination of its role in cancer.

7.
Int J Mol Sci ; 21(10)2020 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-32466143

RESUMO

Genome-wide RNA sequencing has shown that only a small fraction of the human genome is transcribed into protein-coding mRNAs. While once thought to be "junk" DNA, recent findings indicate that the rest of the genome encodes many types of non-coding RNA molecules with a myriad of functions still being determined. Among the non-coding RNAs, long non-coding RNAs (lncRNA) and enhancer RNAs (eRNA) are found to be most copious. While their exact biological functions and mechanisms of action are currently unknown, technologies such as next-generation RNA sequencing (RNA-seq) and global nuclear run-on sequencing (GRO-seq) have begun deciphering their expression patterns and biological significance. In addition to their identification, it has been shown that the expression of long non-coding RNAs and enhancer RNAs can vary due to spatial, temporal, developmental, or hormonal variations. In this review, we explore newly reported information on estrogen-regulated eRNAs and lncRNAs and their associated biological functions to help outline their markedly prominent roles in estrogen-dependent signaling.


Assuntos
Elementos Facilitadores Genéticos , Estrogênios/metabolismo , RNA Longo não Codificante/metabolismo , Pequeno RNA não Traduzido/metabolismo , Transdução de Sinais , Regulação Neoplásica da Expressão Gênica , Humanos , RNA Longo não Codificante/genética , Pequeno RNA não Traduzido/genética , Ativação Transcricional
8.
Mol Cell Endocrinol ; 510: 110819, 2020 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-32311422

RESUMO

Recent technical and other advances in genomics provide unique opportunities to improve our understanding of human physiology and disease predisposition through a detailed analysis of gene structure and expression by examining data in public genome and gene-expression repositories. Yet, the vast majority of human genes remain understudied. This is particularly true of genes for long noncoding RNAs (lncRNAs). Here, we describe the detailed characterization of MIR503HG, a lncRNA gene found on the X chromosome in humans. Using information extracted from public databases, we show that human MIR503HG is a 5-exon gene, and that it is highly conserved among 5 non-human primates spanning over 85 million years ago of evolutionary diversification. MIR503HG is transcribed and processed into multiple distinct RNAs in each of these species through differential exon use and alternative RNA splicing, with a higher abundance of transcripts being found in reproductive tissues, especially during the early stages of ovary and testis development, indicating a possible role in reproductive biology. Furthermore, in select reproductive system cancers, MIR503HG transcripts are downregulated, with higher levels of RNA expression being associated with clinical outcomes. Collectively, these investigations show how the use of genomic, gene expression, and other genetic resources can lead to new insights about human biology and disease, and argue that MIR503HG is worthy of additional study.


Assuntos
Regulação da Expressão Gênica , RNA Longo não Codificante/química , RNA Longo não Codificante/genética , Animais , Genoma Humano , Humanos , Primatas , Prognóstico , Ligação Proteica , RNA Longo não Codificante/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
9.
Adv Clin Chem ; 95: 105-147, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32122521

RESUMO

Long noncoding RNAs (lncRNAs) have recently gained considerable attention as key players in biological regulation; however, the mechanisms by which lncRNAs govern various disease processes remain mysterious and are just beginning to be understood. The ease of next-generation sequencing technologies has led to an explosion of genomic information, especially for the lncRNA class of noncoding RNAs. LncRNAs exhibit the characteristics of mRNAs, such as polyadenylation, 5' methyl capping, RNA polymerase II-dependent transcription, and splicing. These transcripts comprise more than 200 nucleotides (nt) and are not translated into proteins. Directed interrogation of annotated lncRNAs from RNA-Seq datasets has revealed dramatic differences in their expression, largely driven by alterations in transcription, the cell cycle, and RNA metabolism. The fact that lncRNAs are expressed cell- and tissue-specifically makes them excellent biomarkers for ongoing biological events. Notably, lncRNAs are differentially expressed in several cancers and show a distinct association with clinical outcomes. Novel methods and strategies are being developed to study lncRNA function and will provide researchers with the tools and opportunities to develop lncRNA-based therapeutics for cancer.


Assuntos
Antineoplásicos/farmacologia , Neoplasias/tratamento farmacológico , RNA Longo não Codificante/antagonistas & inibidores , Animais , Humanos , Neoplasias/genética , Neoplasias/metabolismo , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo
10.
Biol Reprod ; 102(2): 327-338, 2020 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-31511857

RESUMO

The ovarian hormones estrogen and progesterone orchestrate the transcriptional programs required to direct functions of the uterus for initiation and maintenance of pregnancy. Estrogen, acting via estrogen receptor alpha, regulates gene expression by activating and repressing distinct genes involved in signaling pathways that regulate cellular and physiological responses including cell division, water influx, and immune cell recruitment. Historically, these transcriptional responses have been postulated to reflect a biphasic physiological response. In this study, we explored the transcriptional responses of the ovariectomized mouse uterus to 17ß-estradiol (E2) by RNA-seq to obtain global expression profiles of protein-coding transcripts (mRNAs) and long noncoding RNAs (lncRNAs) following 0.5, 1, 2, and 6 hours of treatment. The E2-regulated mRNA and lncRNA expression profiles in the mouse uterus indicate an association between lncRNAs and mRNAs that regulate E2-driven pathways and reproductive phenotypes in the mouse. The transient E2-regulated transcriptome is reflected in the time-dependent shifting of biological processes regulated in the uterus in response to E2. Moreover, high expression of some conserved lncRNAs that are E2 regulated in the mouse uterus are predictive of low overall survival in endometrial carcinoma patients (e.g., H19, KCNQ1OT1, MIR17HG, and FTX). Collectively, this study (1) describes a genomic approach for identifying E2-regulated lncRNAs that may serve critical function in the uterus and (2) provides new insights into our understanding of the regulation of hormone-regulated transcriptional responses with implications in pregnancy and endometrial pathologies.


Assuntos
Estradiol/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , RNA Longo não Codificante/metabolismo , RNA Mensageiro/metabolismo , Transcriptoma/efeitos dos fármacos , Útero/efeitos dos fármacos , Animais , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Neoplasias da Mama/mortalidade , Bases de Dados Genéticas , Feminino , Ontologia Genética , Neoplasias dos Genitais Femininos/genética , Neoplasias dos Genitais Femininos/metabolismo , Neoplasias dos Genitais Femininos/mortalidade , Humanos , Camundongos , Ovariectomia , RNA Longo não Codificante/genética , RNA Mensageiro/genética , Taxa de Sobrevida , Útero/metabolismo
11.
Biochemistry ; 59(4): 389-399, 2020 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-31746185

RESUMO

Transcription factor 19 (TCF19) plays critical roles in type 1 diabetes and the maintenance of pancreatic ß cells. Recent studies have also implicated TCF19 in cell proliferation of hepatic carcinoma and non-small cell lung carcinoma; however, the mechanism underlying this regulation remains elusive. At the molecular level, TCF19 contains two modules, the plant homeodomain (PHD) finger and the forkhead-associated (FHA) domain, of unclear function. Here, we show that TCF19 mediates hepatocellular carcinoma HepG2 cell proliferation through its PHD finger that recognizes trimethylated lysine 4 of histone 3 (H3K4me3). W316 of the PHD finger of TCF19 is one of the critical residues eliciting this function. Whole genome microarray analysis and orthogonal cell-based assays identified a large subset of genes involved in cell survival and proliferation that depend on TCF19. Our data suggest that TCF19 acts as a pro-oncogene in hepatocellular carcinoma cells and that its functional PHD finger is critical in cell proliferation.


Assuntos
Histonas/metabolismo , Fatores de Transcrição/metabolismo , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/fisiologia , Proteínas de Ligação a DNA/metabolismo , Células Hep G2 , Código das Histonas , Histonas/genética , Humanos , Neoplasias Hepáticas/metabolismo , Lisina/metabolismo , Metilação , Modelos Moleculares , Dedos de Zinco PHD/fisiologia , Ligação Proteica , Fatores de Transcrição/fisiologia
12.
Steroids ; 133: 93-95, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29317255

RESUMO

Long noncoding RNAs (lncRNAs) are implicated in several biological processes, including but not limited to cardiovascular physiology, reproduction, differentiation, metabolism, DNA repair, and inflammation. Under normal physiological conditions, expression of lncRNAs is tissue-specific and tightly regulated. In contrast, prevalent cancer types exhibit aberrant expression of lncRNAs. In this context, lncRNAs can drive cancer cell characteristics by controlling gene expression programs related to tumor suppressive and oncogenic functions. Hence, they can be excellent biomarkers and targets for therapeutic intervention in cancers. Understanding the molecular mechanisms by which lncRNAs drive cancer progression will improve our understanding of the etiology of cancer and suggest new ways to treat this disease. This review will provide a perspective on the role of lncRNAs in cancer initiation and progression.


Assuntos
Neoplasias/genética , RNA Longo não Codificante/genética , Humanos
13.
Mol Cell ; 59(4): 698-711, 2015 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-26236012

RESUMO

We describe a computational approach that integrates GRO-seq and RNA-seq data to annotate long noncoding RNAs (lncRNAs), with increased sensitivity for low-abundance lncRNAs. We used this approach to characterize the lncRNA transcriptome in MCF-7 human breast cancer cells, including >700 previously unannotated lncRNAs. We then used information about the (1) transcription of lncRNA genes from GRO-seq, (2) steady-state levels of lncRNA transcripts in cell lines and patient samples from RNA-seq, and (3) histone modifications and factor binding at lncRNA gene promoters from ChIP-seq to explore lncRNA gene structure and regulation, as well as lncRNA transcript stability, regulation, and function. Functional analysis of selected lncRNAs with altered expression in breast cancers revealed roles in cell proliferation, regulation of an E2F-dependent cell-cycle gene expression program, and estrogen-dependent mitogenic growth. Collectively, our studies demonstrate the use of an integrated genomic and molecular approach to identify and characterize growth-regulating lncRNAs in cancers.


Assuntos
Neoplasias da Mama/genética , Proliferação de Células , Anotação de Sequência Molecular , RNA Longo não Codificante/fisiologia , Sequência de Bases , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Células MCF-7 , Transcriptoma
15.
Methods Mol Biol ; 1288: 375-94, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25827892

RESUMO

Histone chaperones are histone interacting proteins that are involved in various stages of histone metabolism in the cell such as histone storage, transport, nucleosome assembly and disassembly. Histone assembly and disassembly are essential processes in certain DNA-templated phenomena such as replication, repair and transcription in eukaryotes. Since the first histone chaperone Nucleoplasmin was discovered in Xenopus, a plethora of histone chaperones have been identified, characterized and their functional significance elucidated in the last 35 years or so. Some of the histone chaperone containing complexes such as FACT have been described to play a significant role in nucleosome disassembly during transcription elongation. We have reported earlier that human Nucleophosmin (NPM1), a histone chaperone belonging to the Nucleoplasmin family, is a co-activator of transcription. In this chapter, we describe several methods that are used to study the histone chaperone activity of proteins and their role in transcription.


Assuntos
Cromatina/genética , Chaperonas de Histonas/metabolismo , Histonas/metabolismo , Nucleossomos/genética , Transcrição Genética , Animais , Linhagem Celular , Cromatina/metabolismo , Montagem e Desmontagem da Cromatina , Humanos , Técnicas In Vitro , Camundongos , Nucleossomos/metabolismo
16.
J Mol Biol ; 410(5): 997-1007, 2011 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-21763502

RESUMO

Human immunodeficiency virus type 1 (HIV-1) following integration hijacks host cell machineries where chromatinization of the viral genome regulates its latency, transcription, and replication. The cooperation among ATP-dependent chromatin remodeling factors, posttranslational modifying enzymes, and histone chaperones is well established during transcriptional activation in eukaryotes. However, the role of histone chaperones in transcription of the HIV promoter is poorly understood. Previous studies from our group have established the role of the human histone chaperone nucleophosmin (NPM1) in the acetylation-dependent chromatin transcription. NPM1 is known to interact with HIV-Tat. Here, we report that infection by HIV-1 induces the acetylation of histone chaperone NPM1. Acetylation of NPM1 was found to be critical for nuclear localization of Tat as well as Tat-mediated transcription alluding to the critical role for the host factor towards viral pathogenesis. Furthermore, knockdown experiments mediated by small interfering RNA identified the critical role played by the chaperone NPM1 in transcriptional activation of the integrated provirus. These results shed further insights into the possible role of histone chaperone NPM1 acetylation in viral gene transcription, which could be a potential therapeutic target.


Assuntos
Infecções por HIV/metabolismo , HIV-1/genética , Proteínas Nucleares/metabolismo , Ativação Transcricional/genética , Produtos do Gene tat do Vírus da Imunodeficiência Humana/metabolismo , Acetilação , Linhagem Celular , Núcleo Celular/metabolismo , Inativação Gênica , Repetição Terminal Longa de HIV/genética , HIV-1/fisiologia , Humanos , Regiões Promotoras Genéticas/genética , Ligação Proteica , Transporte Proteico , Replicação Viral/genética
17.
Biochemistry ; 50(14): 2780-9, 2011 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-21425800

RESUMO

Linker histone H1 plays an essential role in chromatin organization. Proper deposition of linker histone H1 as well as its removal is essential for chromatin dynamics and function. Linker histone chaperones perform this important task during chromatin assembly and other DNA-templated phenomena in the cell. Our in vitro data show that the multifunctional histone chaperone NPM1 interacts with linker histone H1 through its first acidic stretch (residues 120-132). Association of NPM1 with linker histone H1 was also observed in cells in culture. NPM1 exhibited remarkable linker histone H1 chaperone activity, as it was able to efficiently deposit histone H1 onto dinucleosomal templates. Overexpression of NPM1 reduced the histone H1 occupancy on the chromatinized template of HIV-1 LTR in TZM-bl cells, which led to enhanced Tat-mediated transactivation. These data identify NPM1 as an important member of the linker histone chaperone family in humans.


Assuntos
Cromatina/metabolismo , Histonas/metabolismo , Chaperonas Moleculares/metabolismo , Proteínas Nucleares/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Montagem e Desmontagem da Cromatina , Imunoprecipitação da Cromatina , Células HEK293 , Células HeLa , Histonas/genética , Humanos , Immunoblotting , Chaperonas Moleculares/genética , Dados de Sequência Molecular , Mutação , Proteínas Nucleares/genética , Ligação Proteica , Homologia de Sequência de Aminoácidos
18.
Biochemistry ; 49(7): 1355-7, 2010 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-20073534

RESUMO

The chromatin is comprised of repeating subunits that make up the nucleosome which is composed of an octamer of histones: H3, H4, H2A, and H2B. The replication-dependent and -independent nucleosome assembly occurs in an ordered fashion and is aided by cellular proteins such as histone chaperones and chromatin remodelers. Previously, we found that the histone chaperone NPM1 activates transcription from the chromatin template. Here we report that NPM3, a member of the nucleophosmin/nucleoplasmin family, lacks intrinsic histone chaperone activity, inhibits histone assembly activity of NPM1 in vitro, and dramatically enhances transcription in a cellular system.


Assuntos
Família Multigênica/fisiologia , Nucleoplasminas/fisiologia , Transativadores/fisiologia , Transcrição Genética , Linhagem Celular , Células HeLa , Histonas/antagonistas & inibidores , Histonas/metabolismo , Humanos , Proteínas Nucleares/antagonistas & inibidores , Proteínas Nucleares/química , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteínas Nucleares/fisiologia , Nucleoplasminas/química , Nucleoplasminas/genética , Nucleossomos/química , Nucleossomos/genética , Nucleossomos/fisiologia , Transativadores/química , Transativadores/genética , Regulação para Cima/genética
19.
J Mol Biol ; 397(1): 1-12, 2010 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-20080105

RESUMO

The highly abundant, multifunctional transcriptional positive coactivator 4 (PC4) plays important roles in transcription, replication and DNA repair. Our recent work showed that PC4 is a bona fide non-histone component of chromatin. Here, we report that knockdown of PC4 dramatically alters heterochromatin organization of the genome, accompanied by increased H3K9 (histone H3 at lysine residue 9)/14 acetylation, H3K4 trimethylation and reduction in the level of H3K9 dimethylation. These posttranslational modifications of histone H3 result in overexpression of normally silenced genes (e.g., neural genes) located in heterochromatin. The results of ChIP (chromatin immunoprecipitation) and re-ChIP assays showed that overexpression of a neuronal-specific gene is accompanied by histone hyperacetylation. We further show that PC4 interacts with heterochromatin protein 1alpha, REST/NRSF (RE1-silencing transcription factor/neuron-restrictive silencer factor) and CoREST to establish the repressed state of neural genes in nonneuronal cells. Thus, PC4 plays a crucial role in maintaining a dynamic chromatin state and heterochromatin gene silencing.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica , Inativação Gênica , Heterocromatina/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Proteínas Repressoras/metabolismo , Fatores de Transcrição/metabolismo , Acetilação , Proteínas Cromossômicas não Histona/metabolismo , Proteínas Correpressoras , Epigênese Genética , Técnicas de Silenciamento de Genes , Células HeLa , Heterocromatina/ultraestrutura , Histonas/metabolismo , Humanos , Microscopia de Força Atômica , Canal de Sódio Disparado por Voltagem NAV1.2 , Proteínas do Tecido Nervoso/genética , Regiões Promotoras Genéticas/genética , Ligação Proteica , Canais de Sódio/genética , Canais de Sódio/metabolismo
20.
Mol Cell Biol ; 29(18): 5115-27, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19581289

RESUMO

Nucleophosmin (NPM1) is a multifunctional protein involved in the regulation of centrosome duplication, ribosome biogenesis, genomic stability, histone chaperone function, and transcription. Overexpression of NPM1 is associated with cancers of diverse histological origins. Here, we have found that p300-mediated acetylation of NPM1 modulates its subcellular localization and augments its oncogenic potential. Acetylated NPM1 is predominantly localized in the nucleoplasm, where it associates with transcriptionally active RNA polymerase II. Deacetylation of NPM1 is brought about by human SIRT1 and reduces its transcriptional activation potential. Remarkably, increased levels of acetylated NPM1 were found in grade II and III oral squamous cell carcinoma (OSCC) patient samples. Small interfering RNA (siRNA)-mediated knockdown of NPM1 in an OSCC cell line, followed by microarray analysis and chromatin immunoprecipitation experiments, revealed that some of the genes involved in oral cancer malignancy are regulated by NPM1 and have acetylated NPM1 localized at their promoters. Either suppression of p300 by siRNA or mutation of acetylatable lysine residues of NPM1 resulted in reduced occupancy of acetylated NPM1 on the target gene promoter concomitant with its decreased transcript levels. These observations suggest that acetylated NPM1 transcriptionally regulates genes involved in cell survival and proliferation during carcinogenesis.


Assuntos
Núcleo Celular/metabolismo , Regulação Neoplásica da Expressão Gênica , Genes Neoplásicos , Neoplasias Bucais/genética , Proteínas Nucleares/metabolismo , Ativação Transcricional/genética , Acetilação , Linhagem Celular Tumoral , Proteína p300 Associada a E1A/metabolismo , Técnicas de Silenciamento de Genes , Humanos , Neoplasias Bucais/enzimologia , Neoplasias Bucais/patologia , Regiões Promotoras Genéticas/genética , Transporte Proteico , RNA Polimerase II/metabolismo , Sirtuína 1 , Sirtuínas/metabolismo , Fator de Necrose Tumoral alfa/genética
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