RESUMO
Treacle ribosome biogenesis factor 1 (TCOF1) is responsible for about 80% of mandibular dysostosis (MD) cases. We have formerly identified a correlation between TCOF1 and CNBP (CCHC-type zinc finger nucleic acid binding protein) expression in human mesenchymal cells. Given the established role of CNBP in gene regulation during rostral development, we explored the potential for CNBP to modulate TCOF1 transcription. Computational analysis for CNBP binding sites (CNBP-BSs) in the TCOF1 promoter revealed several putative binding sites, two of which (Hs791 and Hs2160) overlap with putative G-quadruplex (G4) sequences (PQSs). We validated the folding of these PQSs measuring circular dichroism and fluorescence of appropriate synthetic oligonucleotides. In vitro studies confirmed binding of purified CNBP to the target PQSs (both folded as G4 and unfolded) with Kd values in the nM range. ChIP assays conducted in HeLa cells chromatin detected the CNBP binding to TCOF1 promoter. Transient transfections of HEK293 cells revealed that Hs2160 cloned upstream SV40 promoter increased transcription of downstream firefly luciferase reporter gene. We also detected a CNBP-BS and PQS (Dr2393) in the zebrafish TCOF1 orthologue promoter (nolc1). Disrupting this G4 in zebrafish embryos by microinjecting DNA antisense oligonucleotides complementary to Dr2393 reduced the transcription of nolc1 and recapitulated the craniofacial anomalies characteristic of Treacher Collins Syndrome. Both cnbp overexpression and Morpholino-mediated knockdown in zebrafish induced nolc1 transcription. These results suggest that CNBP modulates the transcriptional expression of TCOF1 through a mechanism involving G-quadruplex folding/unfolding, and that this regulation is active in vertebrates as distantly related as bony fish and humans. These findings may have implications for understanding and treating MD.
Assuntos
Quadruplex G , Disostose Mandibulofacial , Animais , Humanos , DNA/metabolismo , Células HEK293 , Células HeLa , Disostose Mandibulofacial/genética , Disostose Mandibulofacial/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Fosfoproteínas/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Fatores de Transcrição/metabolismo , Peixe-Zebra/genética , Peixe-Zebra/metabolismoRESUMO
Treacher Collins Syndrome (TCS) is a genetic disorder with predominantly autosomal dominant inheritance, associated with different mutations in specific genes. This review aimed to evaluate the facial, temporomandibular, zygomatic and bucco-dental phenotype in TCS individuals, and describe surgical and non-surgical solutions for each case in order to improve the quality of life of these individuals. A review of the literature on the craniofacial characteristics of the TCS was carried out, using the PICO strategy, and then a systematic search method was performed in Medline, Scopus, LILACS and SCIELO databases, identifying articles of impact and relevance until 10 June 2020, 240 articles were recovered and only 35 fulfilled the selection criteria. We found the main craniofacial and oral morphological characteristics of these individuals, and the possible functional alterations inducing repercussion in the stomatognathic apparatus. Among other characteristics, the most representative include hypoplasia in the zygomatic and mandibular complex, which can cause difficulty in breathing and feeding. In some cases, cleft palate and malocclusions such as anterior open bite may lead to Angle's Class II malocclusion, sometimes causing problems in the temporomandibular joint. In conclusion, individuals with TCS have specific craniofacial features including maxillary hypoplasia, altered orbital zones, mandibular retrognathia, and temporomandibular disorders. Oral deformities produce to a higher prevalence of caries and calculus formation because of poor hygiene due to the malformations present in these patients.
Assuntos
Fissura Palatina , Disostose Mandibulofacial , Face , Humanos , Mandíbula , Disostose Mandibulofacial/diagnóstico , Disostose Mandibulofacial/epidemiologia , Disostose Mandibulofacial/genética , Qualidade de VidaRESUMO
The acrofacial dysostoses (AFD) are a genetically heterogeneous group of inherited disorders with craniofacial and limb abnormalities. Rodriguez syndrome is a severe, usually perinatal lethal AFD, characterized by severe retrognathia, oligodactyly and lower limb abnormalities. Rodriguez syndrome has been proposed to be a severe form of Nager syndrome, a non-lethal AFD that results from mutations in SF3B4, a component of the U2 small nuclear ribonucleoprotein particle (U2 snRNP). Furthermore, a case with a phenotype intermediate between Rodriguez and Nager syndromes has been shown to have an SF3B4 mutation. We identified heterozygosity for SF3B4 mutations in Rodriguez syndrome, confirming that the phenotype is a dominant disorder that is allelic with Nager syndrome. The mutations led to reduced SF3B4 synthesis and defects in mRNA splicing, primarily exon skipping. The mutations also led to reduced expression in growth plate chondrocytes of target genes, including the DLX5, DLX6, SOX9, and SOX6 transcription factor genes, which are known to be important for skeletal development. These data provide mechanistic insight toward understanding how SF3B4 mutations lead to the skeletal abnormalities observed in the acrofacial dysostoses.
Assuntos
Condrócitos/metabolismo , Deformidades Congênitas da Mão/genética , Disostose Mandibulofacial/genética , Mutação , Fatores de Processamento de RNA/genética , Splicing de RNA , Adulto , Células Cultivadas , Feminino , Deformidades Congênitas da Mão/diagnóstico por imagem , Deformidades Congênitas da Mão/patologia , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Recém-Nascido , Masculino , Disostose Mandibulofacial/diagnóstico por imagem , Disostose Mandibulofacial/patologia , Linhagem , Fenótipo , Fatores de Processamento de RNA/metabolismo , Fatores de Transcrição SOXD/genética , Fatores de Transcrição SOXD/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Genetic disorders occur by excess or absence of chromosomal material, and the consequence of these changes is reflected in morphological and physiological changes. Autosomal disorders, which have dominant inheritance, as cleidocranial dysostosis, Craniofacial syndrome Apert, Treacher Collins and Achondroplasia have peculiar and similar characteristics. Because of their implications in the dental field, the aim of this review is to report on dysostoses, through exposure of general clinical factors and highlighting the signs in the oral cavity. Articles were selected from Lilacs, PubMed and Bireme databases, included in the year 20072014, and the keywords were: cleidocranial dysplasia, craniofacial dysostosis, mandibulofacial dysostosis, dysostosis and oral. Alterations of maxillofacial bones and craniofacial are well documented in the literature, but studies reporting an association between treatment odontologic and dysostoses are scarce. In conclusion, Oral pathological manifestations developed cause difficulty in speech, chewing, breathing, social involvement, and in a general perspective, psychological impairment and physical limitations.
Las enfermedades genéticas se producen debido a un exceso o ausencia de material cromosómico, y la consecuencia de estos cambios se refleja en los cambios morfológicos y fisiológicos. Trastornos autosómicos dominantes que tienen herencia dominante, como la disostosis cleidocraneal, el síndrome craneofacial de Apert, Treacher Collins y acondroplasia tiene características peculiares y similares. Debido a sus implicaciones en el campo de la odontología, el objetivo de esta revisión es hablar, a través de la exposición de los factores clínicos y generales, destacando los signos en la cavidad oral. Se seleccionaron los artículos de las bases de datos Lilacs, PubMed y BIREME, incluyendo los años 2007-2014, y las palabras clave fueron: displasia cleidocraneal, craneofacial mandibulofacial disostosis, disostosis y oral. Los cambios de huesos maxilofaciales y craneofaciales están bien documentados en la literatura, pero los estudios que informaron una asociación entre el tratamiento dental y disostosis son escasos. En conclusion, las manifestaciones orales son causas de dificultades del habla, masticación, respiración y la participación social.
Assuntos
Humanos , Displasia Cleidocraniana/genética , Disostose Craniofacial/genética , Manifestações Bucais , Disostose Mandibulofacial/genéticaRESUMO
Triphalangeal thumb-polysyndactyly syndrome (TPTPS) is an autosomal dominant limb disorder with triphalangeal thumbs, polysyndactyly, and syndactyly. In this study, we describe a four-generation Han Chinese family with eight affected members. Haplotype analysis, Affymetrix SNP 6.0 arrays, qPCR, and gap-PCR were performed. Haplotyping results linked the disease-causing region to the 7q36 region that includes the zone of polarizing activity-regulatory sequence. A 442-kb duplication was found on chromosome 7 that co-segregated with the disease phenotype. The extent of the duplication was determined by qPCR, and the breakpoints were identified by gap-PCR and direct sequencing. This mutation was not detected in normal members in the same family. Our data therefore suggest that this novel microduplication, between 155,913,768 and 156,355,553 bp on chromosome 7, could be considered the cause of TPTPS in this kindred.
Assuntos
Anormalidades Congênitas/genética , Disostose Mandibulofacial/genética , Mutação , Linhagem , Cromossomos Humanos Par 7/genética , Feminino , Loci Gênicos , Humanos , MasculinoRESUMO
Treacher Collins syndrome (TCS) is an autosomal dominant disorder of craniofacial development, and mutations in the TCOF1 gene are responsible for over 90% of TCS cases. The knowledge about the molecular mechanisms responsible for this syndrome is relatively scant, probably due to the difficulty of reproducing the pathology in experimental animals. Zebrafish is an emerging model for human disease studies, and we therefore assessed it as a model for studying TCS. We identified in silico the putative zebrafish TCOF1 ortholog and cloned the corresponding cDNA. The derived polypeptide shares the main structural domains found in mammals and amphibians. Tcof1 expression is restricted to the anterior-most regions of zebrafish developing embryos, similar to what happens in mouse embryos. Tcof1 loss-of-function resulted in fish showing phenotypes similar to those observed in TCS patients, and enabled a further characterization of the mechanisms underlying craniofacial malformation. Besides, we initiated the identification of potential molecular targets of treacle in zebrafish. We found that Tcof1 loss-of-function led to a decrease in the expression of cellular proliferation and craniofacial development. Together, results presented here strongly suggest that it is possible to achieve fish with TCS-like phenotype by knocking down the expression of the TCOF1 ortholog in zebrafish. This experimental condition may facilitate the study of the disease etiology during embryonic development.
Assuntos
Modelos Animais de Doenças , Disostose Mandibulofacial/genética , Disostose Mandibulofacial/metabolismo , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo , Peixe-Zebra , Sequência de Aminoácidos , Animais , Movimento Celular , Tamanho Celular , Biologia Computacional , Face/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Técnicas de Silenciamento de Genes , Humanos , Disostose Mandibulofacial/patologia , Camundongos , Dados de Sequência Molecular , Crista Neural/metabolismo , Crista Neural/patologia , Fenótipo , Fosfoproteínas/química , Fosfoproteínas/deficiência , Homologia de Sequência de Aminoácidos , Crânio/embriologia , Crânio/metabolismo , Fatores de Tempo , Peixe-Zebra/embriologia , Peixe-Zebra/genética , Peixe-Zebra/metabolismo , Proteínas de Peixe-Zebra/química , Proteínas de Peixe-Zebra/deficiênciaRESUMO
BACKGROUND: Treacher Collins syndrome (TCS) is an autosomal dominant craniofacial disorder caused by frameshift deletions or duplications in the TCOF1 gene. These mutations cause premature termination codons, which are predicted to lead to mRNA degradation by nonsense mediated mRNA decay (NMD). Haploinsufficiency of the gene product (treacle) during embryonic development is the proposed molecular mechanism underlying TCS. However, it is still unknown if TCOF1 expression levels are decreased in post-embryonic human cells. METHODS: We have estimated TCOF1 transcript levels through real time PCR in mRNA obtained from leucocytes and mesenchymal cells of TCS patients (n = 23) and controls (n = 18). Mutational screening and analysis of NMD were performed by direct sequencing of gDNA and cDNA, respectively. RESULTS: All the 23 patients had typical clinical features of the syndrome and pathogenic mutations were detected in 19 of them. We demonstrated that the expression level of TCOF1 is 18-31% lower in patients than in controls (p < 0.05), even if we exclude the patients in whom we did not detect the pathogenic mutation. We also observed that the mutant allele is usually less abundant than the wild type one in mesenchymal cells. CONCLUSIONS: This is the first study to report decreased expression levels of TCOF1 in TCS adult human cells, but it is still unknown if this finding is associated to any phenotype in adulthood. In addition, as we demonstrated that alleles harboring the pathogenic mutations have lower expression, we herein corroborate the current hypothesis of NMD of the mutant transcript as the explanation for diminished levels of TCOF1 expression. Further, considering that TCOF1 deficiency in adult cells could be associated to pathologic clinical findings, it will be important to verify if TCS patients have an impairment in adult stem cell properties, as this can reduce the efficiency of plastic surgery results during rehabilitation of these patients.
Assuntos
Disostose Mandibulofacial/genética , Mutação , Proteínas Nucleares/genética , Fosfoproteínas/genética , Transcrição Gênica , Adolescente , Adulto , Células Cultivadas , Criança , Pré-Escolar , Análise Mutacional de DNA , Feminino , Citometria de Fluxo , Humanos , Leucócitos/metabolismo , Masculino , Disostose Mandibulofacial/metabolismo , Células-Tronco Mesenquimais/metabolismo , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Adulto JovemRESUMO
We report on a Brazilian mother and her son affected with mandibulofacial dysostosis, growth and mental retardation, microcephaly, first branchial arch anomalies, and cleft palate. To date only three males and one female, all sporadic cases, with a similar condition have been reported. This article describes the first familial case with this rare condition indicating autosomal dominant or X-linked inheritance.
Assuntos
Fissura Palatina/complicações , Orelha/anormalidades , Genes Ligados ao Cromossomo X/genética , Deficiência Intelectual/complicações , Disostose Mandibulofacial/genética , Microcefalia/complicações , Anormalidades da Pele/complicações , Anormalidades Múltiplas/genética , Criança , Pré-Escolar , Feminino , Genes Dominantes , Humanos , Lactente , Recém-Nascido , Masculino , Disostose Mandibulofacial/complicações , Mães , Núcleo Familiar , Gravidez , SíndromeRESUMO
A Síndrome de Treacher Collins é um distúrbio hereditário caracterizado por anomalias e manifesta-se com diversas variáveis clínicas apresentando incidência aproximada de 1:40.000a 1:70.000 pessoas...
The Treacher Collins syndrome is a hereditary disorder characterized by craniofacial abnormalities and it has several different clinic presentations. Its incidence is around too 1:40.000 and 1. 70.000 habitants...
Assuntos
Disostose Mandibulofacial/diagnóstico , Diagnóstico Diferencial , Disostose Mandibulofacial/cirurgia , Disostose Mandibulofacial/genética , Disostose Mandibulofacial/reabilitação , Literatura de Revisão como AssuntoRESUMO
Treacher Collins syndrome (TCS) is an autosomal dominant craniofacial malformation caused by null mutations in the TCOF1 gene. High inter and intra familial clinical variability, ranging from mild malar hypoplasia to perinatal death due to airway collapse is observed, but, to date, no genotype-phenotype correlation has been reported. Considering haploinsufficiency as the molecular mechanism underlying the disease, we have hypothesized that mutations in the promoter region of the gene, which has never been previously characterized, in trans with a pathogenic mutation, could modulate the phenotype. Therefore, the aims of the present study were to determine the TCOF1 gene's core promoter and to identify mutations in this region that could contribute to the phenotypic variation observed in this syndrome. We have delimitated the minimal promoter to a region of less than 150 bp, with 63% of identity among 5 different species. We screened 1.2 kbp of the TCOF1 5' flanking sequence in the DNA obtained from 21 patients and 51 controls and identified four new single nucleotide polymorphisms (SNPs), one of which (-346C>T), was proved to be functional, as it decreased the promoter activity by 38%. Electrophoretic mobility shift assay (EMSA) analysis demonstrated that the -346T allele impairs DNA-binding to the YY1 transcription factor. This promoter variant represents a candidate allele to explain the clinical variability in patients bearing TCS.