RESUMO
Cas9 is a prokaryotic RNA-guided DNA endonuclease that binds substrates tightly in vitro but turns over rapidly when used to manipulate genomes in eukaryotic cells. Little is known about the factors responsible for dislodging Cas9 or how they influence genome engineering. Unbiased detection through proximity labeling of transient protein interactions in cell-free Xenopus laevis egg extract identified the dimeric histone chaperone facilitates chromatin transcription (FACT) as an interactor of substrate-bound Cas9. FACT is both necessary and sufficient to displace dCas9, and FACT immunodepletion converts Cas9's activity from multi-turnover to single turnover. In human cells, FACT depletion extends dCas9 residence times, delays genome editing, and alters the balance between indel formation and homology-directed repair. FACT knockdown also increases epigenetic marking by dCas9-based transcriptional effectors with a concomitant enhancement of transcriptional modulation. FACT thus shapes the intrinsic cellular response to Cas9-based genome manipulation most likely by determining Cas9 residence times.
Assuntos
Proteína 9 Associada à CRISPR/metabolismo , Proteínas de Ligação a DNA/metabolismo , Genoma Humano , Proteínas de Grupo de Alta Mobilidade/metabolismo , Fatores de Elongação da Transcrição/metabolismo , Animais , Proteínas Associadas a CRISPR/metabolismo , Linhagem Celular , DNA/metabolismo , Quebras de DNA de Cadeia Dupla , Reparo do DNA , Epigênese Genética , Edição de Genes , Técnicas de Silenciamento de Genes , Humanos , Nucleossomos/metabolismo , Xenopus laevisRESUMO
The human FACT (facilitates chromatin transcription) complex, composed of two subunits SPT16 (Suppressor of Ty 16) and SSRP1 (Structure-specific recognition protein-1), plays essential roles in nucleosome remodeling. However, the molecular mechanism of FACT reorganizing the nucleosome still remains elusive. In this study, we demonstrate that FACT displays dual functions in destabilizing the nucleosome and maintaining the original histones and nucleosome integrity at the single-nucleosome level. We found that the subunit SSRP1 is responsible for maintenance of nucleosome integrity by holding the H3/H4 tetramer on DNA and promoting the deposition of the H2A/H2B dimer onto the nucleosome. In contrast, the large subunit SPT16 destabilizes the nucleosome structure by displacing the H2A/H2B dimers. Our findings provide mechanistic insights by which the two subunits of FACT coordinate with each other to fulfill its functions and suggest that FACT may play essential roles in preserving the original histones with epigenetic identity during transcription or DNA replication.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/metabolismo , Nucleossomos/metabolismo , Fatores de Elongação da Transcrição/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Cromatina/metabolismo , DNA/metabolismo , Replicação do DNA , Proteínas de Ligação a DNA/genética , Proteínas de Grupo de Alta Mobilidade/genética , Histonas/metabolismo , Humanos , Modelos Moleculares , Nucleossomos/genética , Ligação Proteica , Multimerização Proteica , Proteínas de Saccharomyces cerevisiae/metabolismo , Células Sf9 , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Fatores de Elongação da Transcrição/genéticaRESUMO
Histone chaperone FACT (facilitates chromatin transcription) is well known to promote chromatin recovery during transcription. However, the mechanism how FACT regulates genome-wide chromatin accessibility and transcription factor binding has not been fully elucidated. Through loss-of-function studies, we show here that FACT component Ssrp1 is required for DNA replication and DNA damage repair and is also essential for progression of cell phase transition and cell proliferation in mouse embryonic fibroblast cells. On the molecular level, absence of the Ssrp1 leads to increased chromatin accessibility, enhanced CTCF binding, and a remarkable change in dynamic range of gene expression. Our study thus unequivocally uncovers a unique mechanism by which FACT complex regulates transcription by coordinating genome-wide chromatin accessibility and CTCF binding.
Assuntos
Fator de Ligação a CCCTC , Cromatina , Proteínas de Ligação a DNA , Regulação da Expressão Gênica , Proteínas de Grupo de Alta Mobilidade , Chaperonas de Histonas , Animais , Camundongos , Fator de Ligação a CCCTC/genética , Fator de Ligação a CCCTC/metabolismo , Cromatina/genética , Replicação do DNA , Chaperonas de Histonas/genética , Proteínas de Ligação a DNA/genética , Proteínas de Grupo de Alta Mobilidade/genética , Células NIH 3T3 , Reparo do DNARESUMO
Chromatin condensation state is the key for retrieving genetic information. High-mobility group protein (HMG) proteins exhibit DNA-binding and bending activities, playing an important role in the regulation of chromatin structure. We have shown that nucleosomes tightly packaged into heterochromatin undergo considerable dynamic histone H2A-H2B maintenance via the direct interaction between HP1/Swi6 and facilitate chromatin transcription (FACT), which is composed of the Spt16/Pob3 heterodimer and Nhp6. In this study, we analyzed the role of Nhp6, an HMG box protein, in the FACT at heterochromatin. Pob3 mutant strains showed derepressed heterochromatin-dependent gene silencing, whereas Nhp6 mutant strains did not show significant defects in chromatin regulation or gene expression, suggesting that these two modules play different roles in chromatin regulation. We expressed a protein fusing Nhp6 to the C-terminus of Pob3, which mimics the multicellular FACT component Ssrp1. The chromatin-binding activity of FACT increased with the number of Nhp6 fused to Pob3, and the heterochromatin formation rate was promoted more strongly. Furthermore, we demonstrated that this promotion of heterochromatinization inhibited the heterochromatic variegation caused by epe1+ disruption. Heterochromatic variegation can be observed in a variety of regulatory steps; however, when it is caused by fluctuations in chromatin arrangement, it can be eliminated through the strong recruitment of the FACT complex.
Assuntos
Heterocromatina , Proteínas de Schizosaccharomyces pombe , Schizosaccharomyces , Heterocromatina/metabolismo , Heterocromatina/genética , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Proteínas de Schizosaccharomyces pombe/genética , Regulação Fúngica da Expressão Gênica , Epigênese Genética , Inativação Gênica , Proteínas de Grupo de Alta Mobilidade/metabolismo , Proteínas de Grupo de Alta Mobilidade/genéticaRESUMO
Preservation of nucleosomes during replication has been extensively studied, while the maintenance of nucleosomes during transcription has gotten less attention. The histone chaperone FACT has a role in transcription elongation, although whether it disassembles or assembles nucleosomes during this process is unclear. To elucidate the function of FACT in mammals, we deleted the Ssrp1 subunit of FACT in adult mice. FACT loss is lethal, possibly due to the loss of the earliest progenitors in bone marrow and intestine, while more differentiated cells are not affected. Using cells isolated from several tissues, we show that FACT loss reduces the viability of stem cells but not of cells differentiated in vitro. FACT depletion increases chromatin accessibility in a transcription-dependent manner in adipose mesenchymal stem cells, indicating that nucleosomes are lost in these cells during transcription in the absence of FACT. We also observe activation of interferon (IFN) signaling and the accumulation of immunocytes in organs sensitive to FACT loss. Our data indicate that FACT maintains chromatin integrity during transcription in mammalian adult stem cells, suggesting that chromatin transcription in stem cells and differentiated cells is different.
Assuntos
Proteínas de Grupo de Alta Mobilidade , Nucleossomos , Animais , Sobrevivência Celular/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/genética , Proteínas de Grupo de Alta Mobilidade/metabolismo , Mamíferos/metabolismo , Camundongos , Células-Tronco/metabolismo , Transcrição Gênica , Fatores de Elongação da Transcrição/genéticaRESUMO
Epigenetic regulation contributes to human health and disease, especially cancer, but the mechanisms of many epigenetic regulators remain obscure. Most research is focused on gene regulatory processes, such as mRNA translation and DNA damage repair, rather than the effects on biological functions like mitochondrial activity and oxidative phosphorylation. Here, we identified an essential role for the histone chaperone structure-specific recognition protein 1 (SSRP1) in mitochondrial oxidative respiration in hepatocellular carcinoma, and found that SSRP1 suppression led to mitochondrial damage and decreased oxidative respiration. Further, we focused on TNF receptor-associated protein 1 (TRAP1), the only member of the heat shock protein 90 (HSP90) family, which directly interacts with selected respiratory complexes and affects their stability and activity. We confirmed that SSRP1 downregulation caused a decrease in TRAP1 expression at both the mRNA and protein levels. A chromatin immunoprecipitation assay also showed that SSRP1 could deposit in the TRAP1 promoter region, indicating that SSRP1 maintains mitochondrial function and reactive oxygen species levels through TRAP1. Additionally, rescue experiments and animal experiments confirmed the mechanism of SSRP1 and TRAP1 interaction. In summary, we identified a new mechanism that connects mitochondrial respiration and apoptosis, via SSRP1.
Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Animais , Humanos , Carcinoma Hepatocelular/metabolismo , Fator 1 Associado a Receptor de TNF/metabolismo , Chaperonas de Histonas/metabolismo , Epigênese Genética , Neoplasias Hepáticas/metabolismo , Mitocôndrias/metabolismo , Apoptose/fisiologia , Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/metabolismo , Fatores de Elongação da Transcrição/metabolismo , Proteínas de Choque Térmico HSP90/genética , Proteínas de Choque Térmico HSP90/metabolismoRESUMO
OBJECTIVE: To explore the effects of exosomes loaded with circular RNA PARD3 on EBV-miR-BART4-induced stemness and resistance of cisplatin in nasopharyngeal carcinoma side population (NPC-SP) cells through the miR-579-3p/SIRT1/SSRP1 axis. METHODS: Sixty-five cancer tissues and 65 noncancerous tissues were collected from NPC patients or patients with rhinitis. The expressions of circPARD3, miR-579-3p, SIRT1, and SSRP1 were detected by qRT-PCR, western blot, or immunohistochemistry. In vivo tumor formation assay was performed in nude mice. Immunofluorescence and qRT-PCR were conducted for the determination of CD44 and CD133 expressions, and flow cytometry combined with Hoechst 33,342 dye efflux for identifying SP cells, CCK-8 and EdU assays for cell proliferation, and Transwell assay for migration and invasion. RESULTS: CircPARD3, SIRT1, and SSRP1 were upregulated while miR-579-3p was downregulated in NPC tissues and cells. CircPARD3 was positively correlated with the expressions of SIRT1 and SSRP1, and miR-579-3p was negatively correlated with circPARD3, SIRT1, and SSRP1. Exosomes loaded with circPARD3 promoted EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells, while miR-579-3p reversed the effect of exosomal circPARD3 on EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells. Additionally, miR-579-3p suppressed EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells by regulating SIRT1. SIRT1 upregulated SSRP1 expression by catalyzing H3K4 methylation and down-regulation of SSRP1 reversed the effect of SIRT1 on EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells. CONCLUSION: Exosomes loaded with circPARD3 promoted EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells through the miR-579-3p/SIRT1/SSRP1 axis. Graphical Headlights ⢠EBV-miR-BART4 induces the stemness and resistance of NPC-SP cells. ⢠CircPARD3 regulates SIRT1 by miR-579-3p. ⢠SIRT1 regulates SSRP1 expression by histone methylation. ⢠Exosomes loaded with circPARD3 promotes EBV-miR-BART4-induced NPC-SP cell stemness and resistance by the miR-579-3p/SIRT1/SSRP1 axis.
Assuntos
Exossomos , MicroRNAs , Neoplasias Nasofaríngeas , Animais , Camundongos , Carcinoma Nasofaríngeo/genética , Carcinoma Nasofaríngeo/patologia , Herpesvirus Humano 4/genética , Herpesvirus Humano 4/metabolismo , Cisplatino/farmacologia , Cisplatino/uso terapêutico , MicroRNAs/genética , MicroRNAs/metabolismo , Células da Side Population/metabolismo , Células da Side Population/patologia , Exossomos/genética , Exossomos/metabolismo , Camundongos Nus , Sirtuína 1/genética , Sirtuína 1/metabolismo , Linhagem Celular Tumoral , Neoplasias Nasofaríngeas/tratamento farmacológico , Neoplasias Nasofaríngeas/genética , Proliferação de Células/genética , Regulação Neoplásica da Expressão GênicaRESUMO
BACKGROUND: Long non-coding RNAs (lncRNAs) have been reported to be biological regulators in hepatocellular carcinoma (HCC). DLG1 antisense RNA 1 (DLG1-AS1) has been found to be up-regulated in cervical cancer. However, its function and underlying mechanism in HCC remains unknown. METHODS: DLG1-AS1 expression was assessed in HCC cells and normal cell by RT-qPCR. Luciferase reporter assay, RNA pull down assay and RIP assay were used to demonstrate the interaction between DLG1-AS1 and miR-497-5p. RESULTS: DLG1-AS1 was highly expressed in HCC cells. Silencing of DLG1-AS1 led to the inhibition of HCC cell growth and migration. Besides, MYC induced the transcriptional activation of DLG1-AS1. MYC could facilitate HCC cellular processes by up-regulating DLG1-AS1. MiR-497-5p could interact with DLG1-AS1 in HCC cells. Down-regulation of miR-497-5p could reverse the impacts of DLG1-AS1 silencing on HCC cells. SSRP1 expression could be positively regulated by DLG1-AS1 but was negatively regulated by miR-497-5p. Knockdown of DLG1-AS1 suppressed tumor growth in nude mice. CONCLUSIONS: DLG1-AS1 is activated by MYC and functions as an oncogene in HCC via miR-497-5p/SSRP1 axis.
RESUMO
OBJECTIVE: Facilitates Chromatin Transcription (FACT) complex is a histone chaperone participating in DNA repair-related and transcription-related chromatin dynamics. In this study, we investigated its oncogenic functions, underlying mechanisms and therapeutic implications in human hepatocellular carcinoma (HCC). DESIGN: We obtained HCC and its corresponding non-tumorous liver samples from 16 patients and identified FACT complex as the most upregulated histone chaperone by RNA-Seq. We further used CRISPR-based gene activation and knockout systems to demonstrate the functions of FACT complex in HCC growth and metastasis. Functional roles and mechanistic insights of FACT complex in oxidative stress response were investigated by ChIP assay, flow cytometry, gene expression assays and 4sU-DRB transcription elongation assay. Therapeutic effect of FACT complex inhibitor, Curaxin, was tested in both in vitro and in vivo models. RESULTS: We showed that FACT complex was remarkably upregulated in HCC and contributed to HCC progression. Importantly, we unprecedentedly revealed an indispensable role of FACT complex in NRF2-driven oxidative stress response. Oxidative stress prevented NRF2 and FACT complex from KEAP1-mediated protein ubiquitination and degradation. Stabilised NRF2 and FACT complex form a positive feedback loop; NRF2 transcriptionally activates the FACT complex, while FACT complex promotes the transcription elongation of NRF2 and its downstream antioxidant genes through facilitating rapid nucleosome disassembly for the passage of RNA polymerase. Therapeutically, Curaxin effectively suppressed HCC growth and sensitised HCC cell to sorafenib. CONCLUSION: In conclusion, our findings demonstrated that FACT complex is essential for the expeditious HCC oxidative stress response and is a potential therapeutic target for HCC treatment.
Assuntos
Carcinoma Hepatocelular/fisiopatologia , Proteínas de Ligação a DNA/fisiologia , Proteínas de Grupo de Alta Mobilidade/fisiologia , Chaperonas de Histonas/fisiologia , Neoplasias Hepáticas/fisiopatologia , Estresse Oxidativo/fisiologia , Fatores de Elongação da Transcrição/fisiologia , Animais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Carbazóis/farmacologia , Carbazóis/uso terapêutico , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , Carcinoma Hepatocelular/prevenção & controle , Proteínas de Ciclo Celular/deficiência , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/fisiologia , Linhagem Celular Tumoral , Movimento Celular/genética , Movimento Celular/fisiologia , Proliferação de Células/genética , Proliferação de Células/fisiologia , Proteínas de Ligação a DNA/antagonistas & inibidores , Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/genética , Progressão da Doença , Regulação Neoplásica da Expressão Gênica/fisiologia , Técnicas de Inativação de Genes/métodos , Proteínas de Grupo de Alta Mobilidade/antagonistas & inibidores , Proteínas de Grupo de Alta Mobilidade/biossíntese , Proteínas de Grupo de Alta Mobilidade/genética , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas Experimentais/genética , Neoplasias Hepáticas Experimentais/patologia , Neoplasias Hepáticas Experimentais/fisiopatologia , Neoplasias Hepáticas Experimentais/prevenção & controle , Camundongos Endogâmicos BALB C , Camundongos Nus , Estresse Oxidativo/genética , Sorafenibe/farmacologia , Sorafenibe/uso terapêutico , Fatores de Transcrição/deficiência , Fatores de Transcrição/genética , Fatores de Transcrição/fisiologia , Fatores de Elongação da Transcrição/antagonistas & inibidores , Fatores de Elongação da Transcrição/biossíntese , Fatores de Elongação da Transcrição/genética , Regulação para Cima/fisiologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
In this study, microarray data analysis, real-time quantitative PCR and immunohistochemistry were used to detect the expression levels of SSRP1 in colorectal cancer (CRC) tissue and in corresponding normal tissue. The association between structure-specific recognition protein 1 (SSRP1) expression and patient prognosis was examined by Kaplan-Meier analysis. SSRP1 was knocked down and overexpressed in CRC cell lines, and its effects on proliferation, cell cycling, migration, invasion, cellular energy metabolism, apoptosis, chemotherapeutic drug sensitivity and cell phenotype-related molecules were assessed. The growth of xenograft tumours in nude mice was also assessed. MiRNAs that potentially targeted SSRP1 were determined by bioinformatic analysis, Western blotting and luciferase reporter assays. We showed that SSRP1 mRNA levels were significantly increased in CRC tissue. We also confirmed that this upregulation was related to the terminal tumour stage in CRC patients, and high expression levels of SSRP1 predicted shorter disease-free survival and faster relapse. We also found that SSRP1 modulated proliferation, metastasis, cellular energy metabolism and the epithelial-mesenchymal transition in CRC. Furthermore, SSRP1 induced apoptosis and SSRP1 knockdown augmented the sensitivity of CRC cells to 5-fluorouracil and cisplatin. Moreover, we explored the molecular mechanisms accounting for the dysregulation of SSRP1 in CRC and identified microRNA-28-5p (miR-28-5p) as a direct upstream regulator of SSRP1. We concluded that SSRP1 promotes CRC progression and is negatively regulated by miR-28-5p.
Assuntos
Proliferação de Células/efeitos dos fármacos , Neoplasias Colorretais/tratamento farmacológico , Proteínas de Ligação a DNA/genética , Proteínas de Grupo de Alta Mobilidade/genética , MicroRNAs/genética , Fatores de Elongação da Transcrição/genética , Idoso , Animais , Apoptose/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Cisplatino/administração & dosagem , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Progressão da Doença , Intervalo Livre de Doença , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Feminino , Fluoruracila/administração & dosagem , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Células HCT116 , Xenoenxertos , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , PrognósticoRESUMO
FACT (facilitates chromatin transcription) is a histone chaperone complex important in genomic processes including transcription, DNA replication, and DNA repair. FACT is composed of two proteins, SSRP1 and SPT16, which are highly conserved across eukaryotes. While the mechanisms for FACT in nucleosome reorganization and its relationship to DNA processes is well established, how these roles impact coordination in multicellular animal development are less well understood. Here we characterize the genes encoding FACT complex proteins in the nematode C. elegans. We show that whereas C. elegans includes one SPT16 gene (spt-16), two genes (hmg-3 and hmg-4) encode SSRP1 proteins. Depletion of FACT complex genes interferes with embryonic cell division and cell cycle timing generally, with anterior pharynx development especially sensitive to these defects. hmg-3 and hmg-4 exhibit redundancy for these maternally-provided embryonic functions, but are each uniquely required zygotically for normal germline development. This work provides a framework to study FACT gene function in developmental processes, and identifies that distinct functional requirements for gene duplicates can be manifest within a single tissue.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/metabolismo , Animais , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Proteínas de Transporte , Ciclo Celular , Proteínas de Ciclo Celular/metabolismo , Cromatina , Reparo do DNA , Replicação do DNA , Genes Duplicados/genética , Genes Duplicados/fisiologia , Proteínas de Grupo de Alta Mobilidade/genética , Histonas/metabolismo , Nucleossomos , Fatores de Transcrição/metabolismoRESUMO
The histone chaperone complex facilitates chromatin transcription (FACT) plays important roles in DNA repair, replication, and transcription. In the formation of this complex, structure-specific recognition protein-1 (SSRP1) heterodimerizes with suppressor of Ty 16 (SPT16). SSRP1 also has SPT16-independent functions, but how SSRP1 functions alone remains elusive. Here, using analytical ultracentrifugation (AUC) and small-angle X-ray scattering (SAXS) techniques, we characterized human SSRP1 and that from the amoeba Dictyostelium discoideum and show that both orthologs form an elongated homodimer in solution. We found that substitutions in the SSRP1 pleckstrin homology domain known to bind SPT16 also disrupt SSRP1 homodimerization. Moreover, AUC and SAXS analyses revealed that SSRP1 homodimerization and heterodimerization with SPT16 (resulting in FACT) involve the same SSRP1 surface, namely the PH2 region, and that the FACT complex contains only one molecule of SSRP1. These observations suggest that SSRP1 homo- and heterodimerization might be mutually exclusive. Moreover, isothermal titration calorimetry analyses disclosed that SSRP1 binds both histones H2A-H2B and H3-H4 and that disruption of SSRP1 homodimerization decreases its histone-binding affinity. Together, our results provide evidence for regulation of SSRP1 by homodimerization and suggest a potential role for homodimerization in facilitating SPT16-independent functions of SSRP1.
Assuntos
Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/química , Proteínas de Grupo de Alta Mobilidade/metabolismo , Histonas/metabolismo , Multimerização Proteica , Proteínas de Protozoários/química , Proteínas de Protozoários/metabolismo , Fatores de Elongação da Transcrição/química , Fatores de Elongação da Transcrição/metabolismo , Sequência de Aminoácidos , Dictyostelium , Humanos , Ligação Proteica , Domínios Proteicos , Estrutura Quaternária de ProteínaRESUMO
Cancer cell repopulation through cell cycle re-entry by quiescent (G0 ) cell is thought to be an important mechanism behind treatment failure and cancer recurrence. Facilitates Chromatin Transcription (FACT) is involved in DNA repair, replication and transcription by eviction of histones or loosening their contact with DNA. While FACT expression is known to be high in a range of cancers, the biological significance of the aberrant increase is not clear. We found that in prostate and lung cancer cells FACT mRNA and protein levels were low at G0 compared to the proliferating state but replenished upon cell cycle re-entry. Silencing of FACT with Dox-inducible shRNA hindered cell cycle re-entry by G0 cancer cells, which could be rescued by ectopic expression of FACT. An increase in SKP2, c-MYC and PIRH2 and a decrease in p27 protein levels seen upon cell cycle re-entry were prevented or diminished when FACT was silenced. Further, using mVenus-p27K- infected cancer cells to measure p27 degradation capacity, we confirm that inhibition of FACT at release from quiescence suppressed the p27 degradation capacity resulting in an increased mVenus-p27K- signal. In conclusion, FACT plays an important role in promoting the transition from G0 to the proliferative state and can be a potential therapeutic target to prevent prostate and lung cancer from progression and recurrence.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/metabolismo , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Fatores de Elongação da Transcrição/metabolismo , Células A549 , Carbazóis/farmacologia , Ciclo Celular/genética , Linhagem Celular Tumoral , Proliferação de Células , Inibidor de Quinase Dependente de Ciclina p27/genética , Inibidor de Quinase Dependente de Ciclina p27/metabolismo , Proteínas de Ligação a DNA/antagonistas & inibidores , Proteínas de Ligação a DNA/genética , Regulação Neoplásica da Expressão Gênica , Proteínas de Grupo de Alta Mobilidade/antagonistas & inibidores , Proteínas de Grupo de Alta Mobilidade/genética , Humanos , Neoplasias Pulmonares/genética , Masculino , Células PC-3 , Neoplasias da Próstata/genética , Fase de Repouso do Ciclo Celular/genética , Fatores de Elongação da Transcrição/antagonistas & inibidores , Fatores de Elongação da Transcrição/genéticaRESUMO
An increasing number of reports have indicated that long noncoding RNAs (lncRNAs) are involved in the pathogenesis of colorectal cancer (CRC). However, many lncRNAs remain unidentified in CRC, and their functions are yet to be elucidated. In this study, we investigated the function of lncRNA LOC101927746 in CRC progression. We found that LOC101927746 expression was significantly increased in CRC tissues according to the GEO dataset. Moreover, LOC101927746 expression was positively correlated with tumor stage and metastasis. Additionally, the high expression of LOC101927746 predicted poor prognosis in CRC patients. Functionally, we demonstrated that LOC101927746 silencing significantly suppressed the proliferation, migration, and invasion of CRC cells. In terms of its mechanism, LOC101927746 could serve as a competing endogenous RNA to inhibit miR-584-3p and activate its target gene SSRP1. The expression of miR-584-3p was inversely correlated with either LOC101927746 or SSRP1 in CRC tissues. The overexpression of SSRP1 or inhibition of miR-584-3p could reverse the effects of LOC101927746 knockdown in CRC cells. Taken together, our results suggest that the LOC101927746/miR-584-3p/SSRP1 axis modulates CRC progression.
Assuntos
Neoplasias Colorretais/genética , Proteínas de Ligação a DNA/genética , Regulação Neoplásica da Expressão Gênica , Proteínas de Grupo de Alta Mobilidade/genética , MicroRNAs/genética , Invasividade Neoplásica/genética , RNA Longo não Codificante/genética , Fatores de Elongação da Transcrição/genética , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Neoplasias Colorretais/patologia , Progressão da Doença , Humanos , Invasividade Neoplásica/patologiaRESUMO
Colorectal cancer is one of the most common cancers worldwide with a high incidence rate. Therefore, the molecular basis of colorectal tumorigenesis and evolution must be clarified. Structure-specific recognition protein 1 (SSRP1) is involved in transcriptional regulation, DNA damage repair, and cell cycle regulation and has been confirmed to be highly expressed in various tumor tissues, including colorectal cancer. However, the role of SSRP1 in the development of colorectal cancer remains unclear. Therefore, this study explored the role of SSRP1 in the occurrence and development of colorectal cancer. Using bioinformatics databases, including samples from the Cancer Genome Atlas (TCGA), we confirmed high SSRP1 expression in human colorectal adenocarcinoma tissues. We demonstrated that SSRP1 knockdown via small interfering RNA significantly inhibited the proliferation of colorectal cancer cells and promoted apoptosis through the AKT signaling pathway, suppressing the invasion and migration of colorectal cancer cells in vitro and in vivo. In conclusion, this study demonstrated that SSRP1 silencing influenced the proliferation and apoptosis of colorectal cancer cells via the AKT signaling pathway.
Assuntos
Neoplasias Colorretais/genética , Proteínas de Ligação a DNA/genética , Proteínas de Grupo de Alta Mobilidade/genética , Invasividade Neoplásica/genética , Proteína Oncogênica v-akt/genética , Fatores de Elongação da Transcrição/genética , Apoptose/genética , Carcinogênese/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Neoplasias Colorretais/patologia , Biologia Computacional , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Invasividade Neoplásica/patologia , Transdução de Sinais/genéticaRESUMO
KEY MESSAGE: The histone chaperone FACT is involved in the expression of genes encoding anthocyanin biosynthetic enzymes also upon induction by moderate high-light and therefore contributes to the stress-induced plant pigmentation. The histone chaperone FACT consists of the SSRP1 and SPT16 proteins and associates with transcribing RNAPII (RNAPII) along the transcribed region of genes. FACT can promote transcriptional elongation by destabilising nucleosomes in the path of RNA polymerase II, thereby facilitating efficient transcription of chromatin templates. Transcript profiling of Arabidopsis plants depleted in SSRP1 or SPT16 demonstrates that only a small subset of genes is differentially expressed relative to wild type. The majority of these genes is either up- or down-regulated in both the ssrp1 and spt16 plants. Among the down-regulated genes, those encoding enzymes of the biosynthetic pathway of the plant secondary metabolites termed anthocyanins (but not regulators of the pathway) are overrepresented. Upon exposure to moderate high-light stress several of these genes are up-regulated to a lesser extent in ssrp1/spt16 compared to wild type plants, and accordingly the mutant plants accumulate lower amounts of anthocyanin pigments. Moreover, the expression of SSRP1 and SPT16 is induced under these conditions. Therefore, our findings indicate that FACT is a novel factor required for the accumulation of anthocyanins in response to light-induction.
Assuntos
Antocianinas/biossíntese , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/fisiologia , Vias Biossintéticas/genética , Genes de Plantas , Chaperonas de Histonas/metabolismo , Estresse Fisiológico/genética , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Estresse Fisiológico/efeitos da radiação , Regulação para Cima/efeitos da radiaçãoRESUMO
Our functional genomic RNAi screens have identified the protein components of the FACT (facilitates chromatin transcription) complex, SUPT16H and SSRP1, as top host factors that negatively regulate HIV-1 replication. FACT interacts specifically with histones H2A/H2B to affect assembly and disassembly of nucleosomes, as well as transcription elongation. We further investigated the suppressive role of FACT proteins in HIV-1 transcription. First, depletion of SUPT16H or SSRP1 protein enhances Tat-mediated HIV-1 LTR (long terminal repeat) promoter activity. Second, HIV-1 Tat interacts with SUPT16H but not SSRP1 protein. However, both SUPT16H and SSRP1 are recruited to LTR promoter. Third, the presence of SUPT16H interferes with the association of Cyclin T1 (CCNT1), a subunit of P-TEFb, with the Tat-LTR axis. Removing inhibitory mechanisms to permit HIV-1 transcription is an initial and key regulatory step to reverse post-integrated latent HIV-1 proviruses for purging of reservoir cells. We therefore evaluated the role of FACT proteins in HIV-1 latency and reactivation. Depletion of SUPT16H or SSRP1 protein affects both HIV-1 transcriptional initiation and elongation and spontaneously reverses latent HIV-1 in U1/HIV and J-LAT cells. Similar effects were observed with a primary CD4+ T cell model of HIV-1 latency. FACT proteins also interfere with HTLV-1 Tax-LTR-mediated transcription and viral latency, indicating that they may act as general transcriptional suppressors for retroviruses. We conclude that FACT proteins SUPT16H and SSRP1 play a key role in suppressing HIV-1 transcription and promoting viral latency, which may serve as promising gene targets for developing novel HIV-1 latency-reversing agents.
Assuntos
Proteínas de Ciclo Celular/fisiologia , Proteínas de Ligação a DNA/fisiologia , HIV-1/fisiologia , Proteínas de Grupo de Alta Mobilidade/fisiologia , Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Fatores de Transcrição/fisiologia , Fatores de Elongação da Transcrição/fisiologia , Latência Viral/fisiologia , Linfócitos T CD4-Positivos/fisiologia , Linfócitos T CD4-Positivos/virologia , Proteínas de Ciclo Celular/antagonistas & inibidores , Proteínas de Ciclo Celular/genética , Linhagem Celular , Ciclina T/fisiologia , Proteínas de Ligação a DNA/antagonistas & inibidores , Proteínas de Ligação a DNA/genética , Células HEK293 , Repetição Terminal Longa de HIV , HIV-1/genética , Proteínas de Grupo de Alta Mobilidade/antagonistas & inibidores , Proteínas de Grupo de Alta Mobilidade/genética , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/fisiologia , Vírus Linfotrópico T Tipo 1 Humano/genética , Humanos , Modelos Biológicos , Fator B de Elongação Transcricional Positiva/fisiologia , Regiões Promotoras Genéticas , Interferência de RNA , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/genética , Fatores de Elongação da Transcrição/antagonistas & inibidores , Fatores de Elongação da Transcrição/genética , Latência Viral/genéticaRESUMO
Somatic hypermutation (SHM) requires not only the expression of activation-induced cytidine deaminase, but also transcription in the target regions. However, how transcription guides activation-induced cytidine deaminase in targeting SHM to the Ig genes is not fully understood. Here, we found that the "facilitates chromatin transcription" (FACT) complex promotes SHM by RNAi screening of transcription elongation factors. Furthermore, FACT and histone H3.3, a hallmark of transcription-coupled histone turnover, are enriched at the V(D)J region, 5' flanking sequence of the Sµ switch region and the light chain Jκ 5 segment region in the Ig loci. The regions with the most abundant deposition of FACT and H3.3 were also the most efficient targets of SHM. These results demonstrate the importance of histone-exchanging dynamics at the chromatin of SHM targets, especially in Ig genes.
Assuntos
Cromatina/química , Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/metabolismo , Histonas/genética , Hipermutação Somática de Imunoglobulina , Fatores de Elongação da Transcrição/metabolismo , Linhagem Celular Tumoral , Cromatina/metabolismo , Cinamatos/metabolismo , Citidina Desaminase/genética , Análise Mutacional de DNA , Proteínas de Ligação a DNA/genética , Genes Reporter , Marcadores Genéticos , Proteínas de Fluorescência Verde/metabolismo , Proteínas de Grupo de Alta Mobilidade/genética , Humanos , Higromicina B/análogos & derivados , Higromicina B/metabolismo , Switching de Imunoglobulina , Imunoglobulinas/genética , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Análise de Sequência de DNA , Transcrição Gênica , Fatores de Elongação da Transcrição/genéticaRESUMO
Conventional antitumor therapy is often complicated by the emergence of the so-called cancer stem cells (CSCs), which are characterized by low metabolic rates and high resistance to almost all existing therapies. Many problems of clinical oncology and a poor efficacy of current treatments in particular are ascribed to CSCs. Therefore, it is important to develop new compounds capable of eliminating both rapidly proliferating tumor cells and standard treatment-resistant CSCs. Curaxins have been demonstrated to manifest various types of antitumor activity. Curaxins simultaneously affect at least three key molecular cascades involved in tumor development, including the p53, NF-κB, and HSF1 metabolic pathways. In addition, studies of some curaxins indicate that they can inhibit the transcriptional induction of the genes for matrix metalloproteinases 1 and 8 (MMP1 and MMP8); the PI3K/AKT/mTOR signaling cascades; cIAP-1 (apoptosis protein 1) inhibitor activity; topoisomerase II; and a number of oncogenes, such as c-MYC and others. In vivo experiments have shown that the CSC population increases on gemcitabine monotherapy and is reduced on treatment with curaxin CBL0137. The data support the prospective use of FACT inhibitors as new anticancer drugs with multiple effects on cell metabolism.
RESUMO
OBJECTIVE: The protozoan Toxoplasma gondii expresses large amounts of a 37 kDa Type 2C serine-threonine phosphatase, the so-called TgPP2C which has been suggested to contribute to parasite growth regulation. Ectopic expression in mammalian cells also indicated that the enzyme could regulate growth and survival. In this study, we aimed to investigate the interaction of TgPP2C with human SSRP1 (structure-specific recognition protein 1) and the effects of TgPP2C on cell viability. METHODS: The yeast two hybrid system, His-tag pull-down and co-immunoprecipitation assays were used to confirm the interaction of TgPP2C with SSRP1 and determine the binding domain on SSRP1. The evaluation of cell apoptosis was performed using cleaved caspase-3 antibody and Annexin-V/PI kit combined with flow cytometry. RESULTS: We identified human SSRP1 as an interacting partner of TgPP2C. The C-terminal region of SSRP1 including the amino acids 471 to 538 was specifically mapped as the region responsible for interaction with TgPP2C. The overexpression of TgPP2C down-regulated cell apoptosis and negatively regulated apoptosis induced by DRB, casein kinase II (CKII) inhibitor, through enhanced interaction with SSRP1. CONCLUSION: TgPP2C may be a parasitic factor capable of promoting cell survival through interaction with the host protein SSRP1, thereby creating a favorable environment for parasite growth.