RESUMO
A significant proportion of cancer patients reports a decline in their usual cognitive functions. This impairment may be the consequence of either the malignant disorder itself or the side-effect of the treatment. This impairment in cognitive skills was referred to with a sticky witty name as chemobrain or chemofog, reflecting on the old conception based on the assumption that solely the neurotoxic effect of chemotherapy was responsible for this kind of disturbances. However, today there is increasing evidence proving that such hypotheses can only partially explain the cognitive decline of cancer patients and cancer survivors. As a matter of fact, the cognitive impairment of cancer patients is a much more complex consequence of the malignant disorder than chemobrain or chemofog. Nowadays, this process is described as "cancer-related cognitive impairment" (CRCI). Orv Hetil. 2019; 160(38): 1495-1502.
Assuntos
Antineoplásicos/efeitos adversos , Transtornos Cognitivos/induzido quimicamente , Disfunção Cognitiva/induzido quimicamente , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Neoplasias/tratamento farmacológico , Antineoplásicos/uso terapêutico , Cognição , Transtornos Cognitivos/diagnóstico , Disfunção Cognitiva/diagnóstico , Humanos , Neoplasias/complicaçõesRESUMO
The TFIIH subunit XPB is involved in combined Xeroderma Pigmentosum and Cockayne syndrome (XP-B/CS). Our analyses reveal that XPB interacts functionally with KAT2A, a histone acetyltransferase (HAT) that belongs to the hSAGA and hATAC complexes. XPB interacts with KAT2A-containing complexes on chromatin and an XP-B/CS mutation specifically elicits KAT2A-mediated large-scale chromatin decondensation. In XP-B/CS cells, the abnormal recruitment of TFIIH and KAT2A to chromatin causes inappropriate acetylation of histone H3K9, leading to aberrant formation of transcription initiation complexes on the promoters of several hundred genes and their subsequent overexpression. Significantly, this cascade of events is similarly sensitive to KAT2A HAT inhibition or to the rescue with wild-type XPB. In agreement, the XP-B/CS mutation increases KAT2A HAT activity in vitro. Our results unveil a tight connection between TFIIH and KAT2A that controls higher-order chromatin structure and gene expression and provide new insights into transcriptional misregulation in a cancer-prone DNA repair-deficient disorder.
Assuntos
Cromatina/química , Síndrome de Cockayne/genética , Histona Acetiltransferases/genética , Histonas/metabolismo , Subunidades Proteicas/genética , Fator de Transcrição TFIIH/genética , Xeroderma Pigmentoso/genética , Acetilação , Proteína 9 Associada à CRISPR/genética , Proteína 9 Associada à CRISPR/metabolismo , Sistemas CRISPR-Cas , Linhagem Celular Tumoral , Cromatina/metabolismo , Síndrome de Cockayne/metabolismo , Síndrome de Cockayne/patologia , Fibroblastos/citologia , Fibroblastos/metabolismo , Edição de Genes , Regulação da Expressão Gênica , Histona Acetiltransferases/antagonistas & inibidores , Histona Acetiltransferases/metabolismo , Histonas/genética , Humanos , Modelos Biológicos , Osteoblastos/citologia , Osteoblastos/metabolismo , Cultura Primária de Células , Subunidades Proteicas/metabolismo , RNA Guia de Cinetoplastídeos/genética , RNA Guia de Cinetoplastídeos/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Fator de Transcrição TFIIH/metabolismo , Iniciação da Transcrição Genética , Xeroderma Pigmentoso/metabolismo , Xeroderma Pigmentoso/patologiaRESUMO
Ultraviolet light induced pyrimidine dimer is a helix distortion DNA damage type, which recruits repair complexes. However, proteins of these complexes that take part in both DNA damage recognition and repair have been well-described, the regulation of the downstream steps of nucleotide excision repair (NER) have not been clearly clarified yet. In a high-throughput screen, we identified SerpinB2 (SPB2) as one of the most dramatically upregulated gene in keratinocytes following UV irradiation. We found that both the mRNA and the protein levels of SPB2 were increased upon UV irradiation in various cell lines. Additionally, UV damage induced translocation of SPB2 from the cytoplasm to the nucleus as well as the damage induced foci formation of it. Here we show that SPB2 co-localizes with XPB involved in the NER pathway at UV-induced repair foci. Finally, we demonstrated that UV irradiation promoted the association of SPB2 with ubiquitylated proteins. In basal cell carcinoma tumour cells, we identified changes in the subcellular localization of SPB2. Based on our results, we conclude that SPB2 protein has a novel role in UV-induced NER pathway, since it regulates the removal of the repair complex from the damaged site leading to cancerous malformation.
Assuntos
Dano ao DNA , Reparo do DNA , Melanoma/patologia , Osteossarcoma/patologia , Inibidor 2 de Ativador de Plasminogênio/metabolismo , Raios Ultravioleta/efeitos adversos , Neoplasias Ósseas/etiologia , Neoplasias Ósseas/patologia , Carcinoma Basocelular/etiologia , Carcinoma Basocelular/patologia , DNA Helicases/genética , DNA Helicases/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Humanos , Melanoma/etiologia , Osteossarcoma/etiologia , Inibidor 2 de Ativador de Plasminogênio/genética , Dímeros de Pirimidina , Células Tumorais CultivadasRESUMO
Transcription starts with the assembly of pre-initiation complexes on promoters followed by their opening. Current models suggest that class II gene transcription requires ATP and the TFIIH XPB subunit to open a promoter. Here, we observe that XPB depletion surprisingly leaves transcription virtually intact. In contrast, inhibition of XPB ATPase activity affects transcription, revealing that mRNA expression paradoxically accommodates the absence of XPB while being sensitive to the inhibition of its ATPase activity. The XPB-depleted TFIIH complex is recruited to active promoters and contributes to transcription. We finally demonstrate that the XPB ATPase activity is only used to relieve a transcription initiation block imposed by XPB itself. In the absence of this block, transcription initiation can take place without XPB ATPase activity. These results suggest that a helicase is dispensable for mRNA transcription, thereby unifying the mechanism of promoter DNA opening for the three eukaryotic RNA polymerases.
Assuntos
DNA Helicases/genética , DNA Helicases/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Transcrição Gênica , Adenosina Trifosfatases/metabolismo , Linhagem Celular , Perfilação da Expressão Gênica/métodos , Humanos , Mutação , Regiões Promotoras Genéticas , Análise de Sequência de RNA/métodos , Fator de Transcrição TFIIH/química , Fator de Transcrição TFIIH/metabolismoRESUMO
DNA lesions are sensed by a network of proteins that trigger the DNA damage response (DDR), a signaling cascade that acts to delay cell cycle progression and initiate DNA repair. The Mediator of DNA damage Checkpoint protein 1 (MDC1) is essential for spreading of the DDR signaling on chromatin surrounding Double Strand Breaks (DSBs) by acting as a scaffold for PI3K kinases and for ubiquitin ligases. MDC1 also plays a role both in Non-Homologous End Joining (NHEJ) and Homologous Recombination (HR) repair pathways. Here we identify two novel binding partners of MDC1, the poly (ADP-ribose) Polymerases (PARPs) TNKS1 and 2. We find that TNKSs are recruited to DNA lesions by MDC1 and regulate DNA end resection and BRCA1A complex stabilization at lesions leading to efficient DSB repair by HR and proper checkpoint activation.
Assuntos
Quebras de DNA de Cadeia Dupla , Recombinação Homóloga , Tanquirases/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Sítios de Ligação , Proteínas de Ciclo Celular , Linhagem Celular , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Humanos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Rad51 Recombinase/genética , Rad51 Recombinase/metabolismo , Tanquirases/genética , Transativadores/genética , Transativadores/metabolismo , Ubiquitina-Proteína LigasesRESUMO
In nucleotide excision repair (NER), damage recognition by XPC-hHR23b is described as a critical step in the formation of the preincision complex (PInC) further composed of TFIIH, XPA, RPA, XPG, and ERCC1-XPF. To obtain new molecular insights into the assembly of the PInC, we analyzed its formation independently of DNA damage by using the lactose operator/repressor reporter system. We observed a sequential and ordered self-assembly of the PInC operating upon immobilization of individual NER factors on undamaged chromatin and mimicking that functioning on a bona fide NER substrate. We also revealed that the recruitment of the TFIIH subunit TTDA, involved in trichothiodystrophy group A disorder (TTD-A), was key in the completion of the PInC. TTDA recruits XPA through its first 15 amino acids, depleted in some TTD-A patients. More generally, these results show that proteins forming large nuclear complexes can be recruited sequentially on chromatin in the absence of their natural DNA target and with no reciprocity in their recruitment.
Assuntos
Cromatina/metabolismo , Linhagem Celular Tumoral , Dano ao DNA , Reparo do DNA , Enzimas Reparadoras do DNA/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Endonucleases/metabolismo , Humanos , Proteínas Imobilizadas/química , Proteínas Imobilizadas/metabolismo , Proteínas Nucleares/metabolismo , Domínios e Motivos de Interação entre Proteínas , Multimerização Proteica , Transporte Proteico , Fator de Transcrição TFIIH/metabolismo , Fatores de Transcrição/metabolismo , Proteína de Xeroderma Pigmentoso Grupo A/química , Proteína de Xeroderma Pigmentoso Grupo A/metabolismoRESUMO
All DNA-related processes rely on the degree of chromatin compaction. The highest level of chromatin condensation accompanies transition to mitosis, central for cell cycle progression. Covalent modifications of histones, mainly deacetylation, have been implicated in this transition, which also involves transcriptional repression. Here, we show that the Gcn5-containing histone acetyl transferase complex, Ada Two A containing (ATAC), controls mitotic progression through the regulation of the activity of non-histone targets. RNAi for the ATAC subunits Ada2a/Ada3 results in delayed M/G1 transition and pronounced cell division defects such as centrosome multiplication, defective spindle and midbody formation, generation of binucleated cells and hyperacetylation of histone H4K16 and alpha-tubulin. We show that ATAC localizes to the mitotic spindle and controls cell cycle progression through direct acetylation of Cyclin A/Cdk2. Our data describes a new pathway in which the ATAC complex controls Cyclin A/Cdk2 mitotic function: ATAC/Gcn5-mediated acetylation targets Cyclin A for degradation, which in turn regulates the SIRT2 deacetylase activity. Thus, we have uncovered an essential function for ATAC in regulating Cyclin A activity and consequent mitotic progression.
Assuntos
Acetiltransferases/metabolismo , Mitose/fisiologia , Acetiltransferases/genética , Sequência de Aminoácidos , Animais , Ciclina A/metabolismo , Quinase 2 Dependente de Ciclina/metabolismo , Células HeLa , Humanos , Camundongos , Dados de Sequência Molecular , Células NIH 3T3 , Interferência de RNA , Fuso Acromático/metabolismo , Tubulina (Proteína)/metabolismo , Fatores de Transcrição de p300-CBP/genética , Fatores de Transcrição de p300-CBP/metabolismoRESUMO
BACKGROUND: The tumour suppressor protein p53 is a sequence specific DNA-binding transcription regulator, which exerts its versatile roles in genome protection and apoptosis by affecting the expression of a large number of genes. In an attempt to obtain a better understanding of the mechanisms by which p53 transcription function is regulated, we studied p53 interactions. RESULTS: We identified BIP2 (Bric-à-brac interacting protein 2), the fly homolog of TAF3, a histone fold and a plant homeodomain containing subunit of TFIID, as an interacting partner of Drosophila melanogaster p53 (Dmp53). We detected physical interaction between the C terminus of Dmp53 and the central region of TAF3 both in yeast two hybrid assays and in vitro. Interestingly, DmTAF3 can also interact with human p53, and mammalian TAF3 can bind to both Dmp53 and human p53. This evolutionarily conserved interaction is functionally significant, since elevated TAF3 expression severely and selectively inhibits transcription activation by p53 in human cell lines, and it decreases the level of the p53 protein as well. CONCLUSION: We identified TAF3 as an evolutionarily conserved negative regulator of p53 transcription activation function.
Assuntos
Proteínas de Drosophila/metabolismo , Fator de Transcrição TFIID/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Animais , Western Blotting , Linhagem Celular , Linhagem Celular Tumoral , Proteínas de Drosophila/genética , Drosophila melanogaster , Células HeLa , Humanos , Imunoprecipitação , Modelos Biológicos , Ligação Proteica , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Spodoptera , Fatores Associados à Proteína de Ligação a TATA , Fator de Transcrição TFIID/genética , Transcrição Gênica , Transfecção , Proteína Supressora de Tumor p53/genética , Técnicas do Sistema de Duplo-HíbridoRESUMO
Transactivation-transformation domain-associated protein (TRRAP) is a component of several multiprotein histone acetyltransferase (HAT) complexes implicated in transcriptional regulation. TRRAP was shown to be required for the mitotic checkpoint and normal cell cycle progression. MRE11, RAD50, and NBS1 (product of the Nijmegan breakage syndrome gene) form the MRN complex that is involved in the detection, signaling, and repair of DNA double-strand breaks (DSBs). By using double immunopurification, mass spectrometry, and gel filtration, we describe the stable association of TRRAP with the MRN complex. The TRRAP-MRN complex is not associated with any detectable HAT activity, while the isolated other TRRAP complexes, containing either GCN5 or TIP60, are. TRRAP-depleted extracts show a reduced nonhomologous DNA end-joining activity in vitro. Importantly, small interfering RNA knockdown of TRRAP in HeLa cells or TRRAP knockout in mouse embryonic stem cells inhibit the DSB end-joining efficiency and the precise nonhomologous end-joining process, further suggesting a functional involvement of TRRAP in the DSB repair processes. Thus, TRRAP may function as a molecular link between DSB signaling, repair, and chromatin remodeling.