RESUMO
BACKGROUND: Telomeropathies are a group of inherited disorders caused by germline pathogenic variants in genes involved in telomere maintenance, resulting in excessive telomere attrition that affects several tissues, including hematopoiesis. RecQ and RTEL1 helicases contribute to telomere maintenance by unwinding telomeric structures such as G-quadruplexes (G4), preventing replication defects. Germline RTEL1 variants also are etiologic in telomeropathies. METHODS AND RESULTS: Here we investigated the expression of RecQ (RECQL1, BLM, WRN, RECQL4, and RECQL5) and RTEL1 helicase genes in peripheral blood mononuclear cells (PBMCs) from human telomeropathy patients. The mRNA expression levels of all RecQ helicases, but not RTEL1, were significantly downregulated in patients' primary cells. Reduced RecQ expression was not attributable to cell proliferative exhaustion, as RecQ helicases were not attenuated in T cells exhausted in vitro. An additional fifteen genes involved in DNA damage repair and RecQ functional partners also were downregulated in the telomeropathy cells. CONCLUSION: These findings indicate that the expression of RecQ helicases and functional partners involved in DNA repair is downregulated in PBMCs of telomeropathy patients.
Assuntos
Leucócitos Mononucleares , RecQ Helicases , Adulto , Feminino , Humanos , Masculino , DNA Helicases/genética , DNA Helicases/metabolismo , Reparo do DNA/genética , Leucócitos Mononucleares/metabolismo , RecQ Helicases/genética , RecQ Helicases/metabolismo , Telômero/metabolismo , Telômero/genética , Homeostase do Telômero/genéticaRESUMO
Bloom syndrome is a rare autosomal recessive disorder with less than 300 cases reported in the literature. Bloom syndrome is characterized by chromosome instability, physical stigmata, growth deficiency, immunodeficiency, and a predisposition to cancer, most commonly leukemias, although solid tumors are reported as well. Bloom syndrome occurs in multiple ethnic groups with a higher incidence in persons of Ashkenazi Jewish origin. Few patients of Hispanic ethnicity have been reported. We report here a Mexican American family with a BLM pathogenic variant, c.2506_2507delAG, previously reported in a single patient from Mexico. In this family of four siblings, three have phenotypic features of Bloom syndrome, and BLM gene mutation was homozygous in these affected individuals. Our proband developed a rhabdomyosarcoma. Analysis of surrounding markers in the germline DNA revealed a common haplotype, suggesting a previously unrecognized founder mutation in the Hispanic population of Mexican origin.
Assuntos
Síndrome de Bloom/genética , Americanos Mexicanos , Mutação , Rabdomiossarcoma/complicações , Rabdomiossarcoma/genética , Alelos , Síndrome de Bloom/patologia , Pré-Escolar , Predisposição Genética para Doença/genética , Homozigoto , Humanos , Masculino , México/epidemiologia , Linhagem , Polimorfismo de Nucleotídeo Único , RecQ Helicases/genética , Rabdomiossarcoma/patologiaRESUMO
BACKGROUND: The Werner syndrome protein (WRN) belongs to the RecQ family of helicases and its loss of function results in the premature aging disease Werner syndrome (WS). We previously demonstrated that an early cellular change induced by WRN depletion is a posttranscriptional decrease in the levels of enzymes involved in metabolic pathways that control macromolecular synthesis and protect from oxidative stress. This metabolic shift is tolerated by normal cells but causes mitochondria dysfunction and acute oxidative stress in rapidly growing cancer cells, thereby suppressing their proliferation. RESULTS: To identify the mechanism underlying this metabolic shift, we examined global protein synthesis and mRNA nucleocytoplasmic distribution after WRN knockdown. We determined that WRN depletion in HeLa cells attenuates global protein synthesis without affecting the level of key components of the mRNA export machinery. We further observed that WRN depletion affects the nuclear export of mRNAs and demonstrated that WRN interacts with mRNA and the Nuclear RNA Export Factor 1 (NXF1). CONCLUSIONS: Our findings suggest that WRN influences the export of mRNAs from the nucleus through its interaction with the NXF1 export receptor thereby affecting cellular proteostasis. In summary, we identified a new partner and a novel function of WRN, which is especially important for the proliferation of cancer cells.
Assuntos
Núcleo Celular/metabolismo , Neoplasias/metabolismo , RNA Mensageiro/genética , Helicase da Síndrome de Werner/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/fisiologia , Células HeLa , Humanos , Redes e Vias Metabólicas/fisiologia , Oxirredução , Processamento Pós-Transcricional do RNA/fisiologia , Transporte de RNA/fisiologia , Proteínas de Ligação a RNA/metabolismo , RecQ Helicases/genética , Síndrome de Werner/metabolismoRESUMO
Birth defects are structural and/or functional malformations present at birth that cause physical or mental disability and are important public health problems. Our study was aimed at genetic analysis and prenatal diagnosis of congenital anomalies to understand the cause of certain birth defects. Karyotypes and array-comparative genomic hybridization (aCGH) were performed on a pregnant woman, surrounding amniotic fluid, and her husband. A short-stature panel genetic test was conducted in accordance with the phenotype of the fetus. Following examination, it was determined that the karyotype and aCGH results were normal. The RECQL4 gene in the fetus showed compound heterozygous mutations, and each parent was found to be a carrier of one of the mutations. The two heterozygous mutations (c.2059-1G>C and c.2141_2142delAG) were detected in the RECQL4 (NM_004260) gene in the fetus; therefore, the fetus was predicted to have Baller-Gerold syndrome. These two mutations have not previously been reported. In addition, these results identified a 25% risk of the parents having a sec-ond conceptus with this congenital disease. Therefore, prenatal genetic diagnosis was highly recommended for future pregnancies.
Assuntos
Craniossinostoses/diagnóstico , Heterozigoto , Mutação , Rádio (Anatomia)/anormalidades , RecQ Helicases/genética , Adulto , Hibridização Genômica Comparativa , Craniossinostoses/genética , Feminino , Humanos , Cariotipagem , Masculino , Gravidez , Diagnóstico Pré-NatalRESUMO
In this study, we investigated the association between a RECQL genetic polymorphism and osteosarcoma in a Chinese population. We selected rs820196 in the RECQL5 gene and genotyped 185 patients with osteosarcoma and 201 age- and gender-matched non-cancer controls. We found that the CC genotype was more frequent in the osteosarcoma group compared to the control group (P = 0.011). We also found that the C allele was more common in osteosarcoma patients than that in control subjects (P = 0.004). Our results suggested that the RECQL5 genetic polymorphism was associated with osteosarcoma in a Chinese population.
Assuntos
Povo Asiático/genética , Predisposição Genética para Doença , Osteossarcoma/genética , Polimorfismo de Nucleotídeo Único , RecQ Helicases/genética , Adulto , Alelos , Estudos de Casos e Controles , Feminino , Técnicas de Genotipagem , Haplótipos , Humanos , Masculino , Adulto JovemRESUMO
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
TATA box is the most studied core promoter element and has a well-described transcription mechanism. However, most metazoan promoters lack TATA box and contain other core promoter elements. One of such elements is HomolD box, which was first described in promoters of ribosomal protein genes in Schizosaccharomyces pombe, and studies performed in this model showed that transcription directed by HomolD box is dependent on RNAPII machinery, and the HomolD-binding protein was Rrn7, a component of RNAPI core factor. Nevertheless, the mechanisms that underlie HomolD-dependent transcription are still unknown. The purpose of this study is to determine the mechanism of transcription directed by human HomolD box. By stepwise purification through different ion exchange columns and affinity chromatography, we purified two proteins: DDB1 and RECQL (DNA damage-binding protein 1 and ATP-dependent DNA helicase Q1 respectively). These proteins showed specific HomolD-binding activity and were required for in vitro HomolD-directed transcription. Recombinant RECQL, but not DDB1, presented HomolD-binding activity in vitro. Both proteins bound to HomolD box in vivo, which could be explained because these proteins co-immunoprecipitated. Additionally, RNAPII machinery was also required to transcription. Collectively, these data suggest that HomolD-containing promoters require the RNAPII machinery and the proteins DDB1 and RECQL for an accurate transcription.