RESUMO
Chromatin remodeler proteins exert an important function in promoting dynamic modifications in the chromatin architecture, performing a central role in regulating gene transcription. Deregulation of these molecular machines may lead to striking perturbations in normal cell function. The CHD7 gene is a member of the chromodomain helicase DNA-binding family and, when mutated, has been shown to be the cause of the CHARGE syndrome, a severe developmental human disorder. Moreover, CHD7 has been described to be essential for neural stem cells and it is also highly expressed or mutated in a number of human cancers. However, its potential role in glioblastoma has not yet been tested. Here, we show that CHD7 is up-regulated in human glioma tissues and we demonstrate that CHD7 knockout (KO) in LN-229 glioblastoma cells suppresses anchorage-independent growth and spheroid invasion in vitro. Additionally, CHD7 KO impairs tumor growth and increases overall survival in an orthotopic mouse xenograft model. Conversely, ectopic overexpression of CHD7 in LN-428 and A172 glioblastoma cell lines increases cell motility and invasiveness in vitro and promotes LN-428 tumor growth in vivo. Finally, RNA-seq analysis revealed that CHD7 modulates a specific transcriptional signature of invasion-related target genes. Further studies should explore clinical-translational implications for glioblastoma treatment.
Assuntos
Movimento Celular , DNA Helicases/fisiologia , Proteínas de Ligação a DNA/fisiologia , Glioblastoma/patologia , Animais , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Técnicas de Silenciamento de Genes , Glioblastoma/metabolismo , Humanos , Camundongos , Camundongos Nus , Invasividade Neoplásica , Transplante de NeoplasiasRESUMO
Entamoeba histolytica, the protozoan responsible for human amoebiasis, exhibits a great genome plasticity that is probably related to homologous recombination events. It contains the RAD52 epistasis group genes, including Ehrad51 and Ehrad54, and the Ehblm gene, which are key homologous recombination factors in other organisms. Ehrad51 and Ehrad54 genes are differentially transcribed in trophozoites when DNA double-strand breaks are induced by ultraviolet-C irradiation. Moreover, the EhRAD51 recombinase is overexpressed at 30 min in the nucleus. Here, we extend our analysis of the homologous recombination mechanism in E. histolytica by studying EhRAD51, EhRAD54, and EhBLM expression in response to DNA damage. Bioinformatic analyses show that EhRAD54 has the molecular features of homologous proteins, indicating that it may have similar functions. Western blot assays evidence the differential expression of EhRAD51, EhRAD54, and EhBLM at different times after DNA damage, suggesting their potential roles in the different steps of homologous recombination in this protozoan.
Assuntos
Reparo do DNA , Entamoeba histolytica/metabolismo , Recombinação Homóloga , Proteínas de Protozoários/fisiologia , Sequência de Aminoácidos , Animais , Núcleo Celular/química , Sequência Consenso , Citoplasma/química , Quebras de DNA de Cadeia Dupla , DNA Helicases/química , DNA Helicases/genética , DNA Helicases/fisiologia , Reparo do DNA/genética , DNA de Protozoário/genética , DNA de Protozoário/efeitos da radiação , Entamoeba histolytica/genética , Entamoeba histolytica/efeitos da radiação , Genes de Protozoários , Recombinação Homóloga/genética , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Conformação Proteica , Proteínas de Protozoários/química , Proteínas de Protozoários/genética , Rad51 Recombinase/genética , Rad51 Recombinase/fisiologia , RecQ Helicases/genética , RecQ Helicases/fisiologia , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Fatores de Tempo , Raios UltravioletaRESUMO
Cockayne is a segmental progeroid syndrome that has autosomal recessive inheritance pattern. It is mainly characterized by Intrauterine growth retardation, severe postnatal growth deficiency, cachectic dwarfism, microcephaly, wizened face, sensorineural hearing loss, cataracts, dental caries, cardiac arrhythmias, hypertension, atherosclerosis, proteinuria, micropenis, renal failure, skeletal abnormalities, skin photosensitivity, decreased subcutaneous adipose tissue, cerebral atrophy, dementia, basal ganglia calcifications, ataxia and apraxia. It has a complex phenotype given by genetic heterogeneity. There are five gene responsible for this syndrome: CSA, CSB, XPB, XPD and XPG, in which various mutations have been found. The biochemical effect of these mutations includes dysfunctional protein of the repair system for oxidative damage to DNA, the complex coupled to transcription and the nucleotide excision repair system. Considering the role played for these proteins and its effects on clinical phenotype when they are deficient, we suggest that these genes might be candidates for analyzing susceptibility to common chronic degenerative diseases related to oxidative stress and aging.
Assuntos
Síndrome de Cockayne/genética , Dano ao DNA , Reparo do DNA/genética , Carbidopa/uso terapêutico , Síndrome de Cockayne/diagnóstico , Síndrome de Cockayne/tratamento farmacológico , Síndrome de Cockayne/metabolismo , Síndrome de Cockayne/patologia , DNA Helicases/deficiência , DNA Helicases/genética , DNA Helicases/fisiologia , Enzimas Reparadoras do DNA/deficiência , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/fisiologia , Proteínas de Ligação a DNA/deficiência , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/fisiologia , Diagnóstico Diferencial , Endonucleases/deficiência , Endonucleases/genética , Endonucleases/fisiologia , Genes Recessivos , Predisposição Genética para Doença , Genótipo , Transtornos do Crescimento/diagnóstico , Humanos , Levodopa/uso terapêutico , Mutação , Proteínas Nucleares/deficiência , Proteínas Nucleares/genética , Proteínas Nucleares/fisiologia , Estresse Oxidativo/genética , Fenótipo , Transtornos de Fotossensibilidade/diagnóstico , Proteínas de Ligação a Poli-ADP-Ribose , Fatores de Transcrição/deficiência , Fatores de Transcrição/genética , Fatores de Transcrição/fisiologia , Proteína Grupo D do Xeroderma Pigmentoso/deficiência , Proteína Grupo D do Xeroderma Pigmentoso/genética , Proteína Grupo D do Xeroderma Pigmentoso/fisiologiaRESUMO
The nucleolus has been considered originally only as the site for the ribosome synthesis, but now it is well known that it represents a dynamic nuclear structure involved in important cellular processes. Several evidences have demonstrated that the nucleolus regulates the cellular senescence. Specific mutations on the DNAs codifying for nucleolar proteins induced premature senescence from yeast to human. The failure to repress the genes transcription codifying for damaged rRNA, and the mutations in DNA helicases, which minimizes the formation of DNA extra-chromosomal circles codifying for rRNA, modify the nucleolar structure and induce premature senescence in yeast. Similarly, in humans, the reduction of these DNA helicases levels, which are localized in the nucleoli and participate in maintenance of genomic integrity, helps to the development of those diseases associated with premature senescence. Furthermore, the presence in the nucleolus of some telomerase components, indicates that part of the biosynthesis of this enzyme occurred in this nuclear structure; suggesting a communication between the nucleolus and the synthesis of the telomeres in the regulation of cell senescence. On the other hand, the nucleolus sequesters proteins to regulate its own biological activity, from the start to the end of cellular replication. In addition this nuclear structure is involved in the biosynthesis of most cellular ribonucleoprotein particles, as well as in cell cycle regulation, making it central to gene expression. In conclusion, the nucleolus became a multifunctional subnuclear structure involved from cell proliferation to cell senescence.
Assuntos
Nucléolo Celular/fisiologia , Senescência Celular/fisiologia , Proteína Supressora de Tumor p53/fisiologia , Síndrome de Werner/genética , Dano ao DNA/fisiologia , DNA Helicases/fisiologia , Genes de RNAr/fisiologia , Humanos , Telômero/fisiologiaRESUMO
El nucléolo, considerado únicamente como el sitio de síntesis de los ribosomas, actualmente representa una estructura nuclear dinámica que participa en la regulación de importantes procesos celulares. Numerosas evidencias han demostrado que el envejecimiento celular es una de las diversas funciones que son controladas por el nucléolo. Las mutaciones en las proteínas de localización nucleolar promueven el envejecimiento prematuro en levaduras y humanos. La carencia de represión en la transcripción de genes que codifican para el ARNr que se encuentran dañados, y las mutaciones en las helicasas del ADN encargadas de minimizar la formación de círculos extra-cromosómicos del ADN que codifica para el ARNr, provocan modificaciones en la estructura del nucléolo e inducen envejecimiento prematuro en levaduras. De igual manera, en los humanos la carencia de las helicasas del ADN localizadas en el nucléolo y que participan en el mantenimiento de la integridad genómica, favorecen el desarrollo de aquellas enfermedades asociadas con el envejecimiento acelerado. Además, la presencia de algunos componentes de la telomerasa en el nucléolo, indica que parte de la biosíntesis de esta enzima se realiza en esta estructura nuclear, sugiriendo una conexión entre el nucléolo y la síntesis de los telómeros en la regulación del envejecimiento celular. Por otra parte, el nucléolo secuestra proteínas para regular su actividad biológica durante el inicio o término de la vida replicativa celular.
The nucleolus has been considered originally only as the site for the ribosome synthesis, but now it is well known that it represents a dynamic nuclear structure involved in important cellular processes. Several evidences have demonstrated that the nucleolus regulates the cellular senescence. Specific mutations on the DNAs codifying for nucleolar proteins induced premature senescence from yeast to human. The failure to repress the genes transcription codifying for damaged rRNA, and the mutations in DNA helicases, which minimizes the formation of DNA extra-chromosomal circles codifying for rRNA, modify the nucleolar structure and induce premature senescence in yeast. Similarly, in humans, the reduction of these DNA helicases levels, which are localized in the nucleoli and participate in maintenance of genomic integrity, helps to the development of those diseases associated with premature senescence. Furthermore, the presence in the nucleolus of some telomerase components, indicates that part of the biosynthesis of this enzyme occurred in this nuclear structure; suggesting a communication between the nucleolus and the synthesis of the telomeres in the regulation of cell senescence. On the other hand, the nucleolus sequesters proteins to regulate its own biological activity, from the start to the end of cellular replication. In addition this nuclear structure is involved in the biosynthesis of most cellular ribonucleoprotein particles, as well as in cell cycle regulation, making it central to gene expression. In conclusion, the nucleolus became a multifunctional subnuclear structure involved from cell proliferation to cell senescence.
Assuntos
Humanos , Senescência Celular/fisiologia , Nucléolo Celular/fisiologia , /fisiologia , Síndrome de Werner/genética , Dano ao DNA/fisiologia , DNA Helicases/fisiologia , Genes de RNAr/fisiologia , Telômero/fisiologiaRESUMO
El nucléolo, considerado únicamente como el sitio de síntesis de los ribosomas, actualmente representa una estructura nuclear dinámica que participa en la regulación de importantes procesos celulares. Numerosas evidencias han demostrado que el envejecimiento celular es una de las diversas funciones que son controladas por el nucléolo. Las mutaciones en las proteínas de localización nucleolar promueven el envejecimiento prematuro en levaduras y humanos. La carencia de represión en la transcripción de genes que codifican para el ARNr que se encuentran dañados, y las mutaciones en las helicasas del ADN encargadas de minimizar la formación de círculos extra-cromosómicos del ADN que codifica para el ARNr, provocan modificaciones en la estructura del nucléolo e inducen envejecimiento prematuro en levaduras. De igual manera, en los humanos la carencia de las helicasas del ADN localizadas en el nucléolo y que participan en el mantenimiento de la integridad genómica, favorecen el desarrollo de aquellas enfermedades asociadas con el envejecimiento acelerado. Además, la presencia de algunos componentes de la telomerasa en el nucléolo, indica que parte de la biosíntesis de esta enzima se realiza en esta estructura nuclear, sugiriendo una conexión entre el nucléolo y la síntesis de los telómeros en la regulación del envejecimiento celular. Por otra parte, el nucléolo secuestra proteínas para regular su actividad biológica durante el inicio o término de la vida replicativa celular.(AU)
The nucleolus has been considered originally only as the site for the ribosome synthesis, but now it is well known that it represents a dynamic nuclear structure involved in important cellular processes. Several evidences have demonstrated that the nucleolus regulates the cellular senescence. Specific mutations on the DNAs codifying for nucleolar proteins induced premature senescence from yeast to human. The failure to repress the genes transcription codifying for damaged rRNA, and the mutations in DNA helicases, which minimizes the formation of DNA extra-chromosomal circles codifying for rRNA, modify the nucleolar structure and induce premature senescence in yeast. Similarly, in humans, the reduction of these DNA helicases levels, which are localized in the nucleoli and participate in maintenance of genomic integrity, helps to the development of those diseases associated with premature senescence. Furthermore, the presence in the nucleolus of some telomerase components, indicates that part of the biosynthesis of this enzyme occurred in this nuclear structure; suggesting a communication between the nucleolus and the synthesis of the telomeres in the regulation of cell senescence. On the other hand, the nucleolus sequesters proteins to regulate its own biological activity, from the start to the end of cellular replication. In addition this nuclear structure is involved in the biosynthesis of most cellular ribonucleoprotein particles, as well as in cell cycle regulation, making it central to gene expression. In conclusion, the nucleolus became a multifunctional subnuclear structure involved from cell proliferation to cell senescence.(AU)
Assuntos
Humanos , Nucléolo Celular/fisiologia , Senescência Celular/fisiologia , Proteína Supressora de Tumor p53/fisiologia , Síndrome de Werner/genética , Dano ao DNA/fisiologia , DNA Helicases/fisiologia , Genes de RNAr/fisiologia , Telômero/fisiologiaRESUMO
The Rhizobium etli ruvA and ruvB genes were cloned through a PCR-based approach, using degenerate primers matching conserved sectors in the amino acid sequences of RuvB from eight bacterial species. Comparative analysis of the predicted polypeptides for RuvA and RuvB of R. etli showed highly conserved blocks with the corresponding homologs in other bacteria; RuvB depicts characteristic motifs for DNA helicases (ATP-binding and DEXH-box motifs). An R. etli ruvB::loxP Sp mutant was constructed by interposon mutagenesis. This mutant was highly sensitive to DNA-damaging agents, such as methyl methanesulfonate and nitrofurantoin, implying a deficiency in DNA repair. Homologous and homeologous conjugational recombination was reduced almost tenfold in the ruvB::loxP Sp mutant; a recombination defect was also observed in assays employing recombination between small plasmids, albeit at a smaller magnitude. Although the ruvA and ruvB genes are contiguous in R. etli, complementation studies suggest that they are expressed independently.