RESUMO
Recent studies have unequivocally confirmed the presence of 5-methylcytosine (m5C) in mammalian mRNAs while indicating significant functional roles for this internal base modification type. Here, a brief history of m5C epitranscriptome research and a discussion of the important ways in which the field may now progress is presented.
Assuntos
5-Metilcitosina/metabolismo , Técnicas Genéticas , RNA Mensageiro/metabolismo , tRNA Metiltransferases/metabolismo , Animais , Códon de Terminação , Humanos , Mamíferos/genética , Metilação , TranscriptomaRESUMO
The highly abundant N6-methyladenosine (m6A) RNA modification affects most aspects of mRNA function, yet the precise function of the rarer 5-methylcytidine (m5C) remains largely unknown. Here, we map m5C in the human transcriptome using methylation-dependent individual-nucleotide resolution cross-linking and immunoprecipitation (miCLIP) combined with RNA bisulfite sequencing. We identify NSUN6 as a methyltransferase with strong substrate specificity towards mRNA. NSUN6 primarily targeted three prime untranslated regions (3'UTR) at the consensus sequence motif CTCCA, located in loops of hairpin structures. Knockout and rescue experiments revealed enhanced mRNA and translation levels when NSUN6-targeted mRNAs were methylated. Ribosome profiling further demonstrated that NSUN6-specific methylation correlated with translation termination. While NSUN6 was dispensable for mouse embryonic development, it was down-regulated in human tumours and high expression of NSUN6 indicated better patient outcome of certain cancer types. In summary, our study identifies NSUN6 as a methyltransferase targeting mRNA, potentially as part of a quality control mechanism involved in translation termination fidelity.
Assuntos
Citidina/análogos & derivados , Processamento Pós-Transcricional do RNA , RNA Mensageiro/metabolismo , tRNA Metiltransferases/metabolismo , Regiões 3' não Traduzidas , Animais , Sequência de Bases , Linhagem Celular Tumoral , Uso do Códon , Sequência Consenso , Citidina/metabolismo , Células-Tronco Embrionárias , Técnicas de Inativação de Genes , Genes Reporter , Células HEK293 , Humanos , Imunoprecipitação , Metilação , Camundongos , Camundongos Knockout , Mutagênese Sítio-Dirigida , RNA Mensageiro/genética , Transcriptoma , tRNA Metiltransferases/deficiênciaRESUMO
De novo sequence-level surveys of transcriptomes have previously relied on sequencing via a DNA intermediate. While such methods can yield massive data sets, various problems mean that these do not always accurately reflect the true innate composition of transcriptomes. Enter Garalde et al., who present for the first time highly parallel native RNA-Sequencing (RNA-seq), with potentially disruptive future-implications for the transcriptomics field.
Assuntos
Sequenciamento de Nucleotídeos em Larga Escala , Análise de Sequência de DNA , RNA , TranscriptomaRESUMO
Biallelic loss-of-function NSUN2 mutations have recently been associated with cases of Autism Spectrum Condition (ASC), and NSun2-deficiency was also previously shown to cause a severe autosomal recessive intellectually disability disorder syndrome in which patients can sometimes display autistic behaviour. It has been demonstrated that NSUN2 can control protein synthesis rates via direct regulation of RNA methylation, and it is therefore of interest that other studies have suggested protein synthesis-dependent synaptic plasticity dysregulation as a mechanism for learning difficulties in various other autism-expressing conditions and disorders. Here we investigated NMDAR-LTP in a murine transgenic model harbouring loss-of-function mutation in the NSun2 gene and find an impairment of a protein synthesis-dependent form of this synaptic plasticity pathway. Our findings support the idea that NMDAR-LTP mis-regulation may represent a previously underappreciated mechanism associated with autism phenotypes.
Assuntos
Transtorno do Espectro Autista/genética , Hipocampo/metabolismo , Potenciação de Longa Duração/genética , Metiltransferases/genética , Receptores de N-Metil-D-Aspartato/fisiologia , Animais , Transtorno do Espectro Autista/metabolismo , Deficiência Intelectual/genética , Deficiência Intelectual/metabolismo , Metiltransferases/metabolismo , Camundongos , Camundongos Transgênicos , MutaçãoRESUMO
Whether protein synthesis and cellular stress response pathways interact to control stem cell function is currently unknown. Here we show that mouse skin stem cells synthesize less protein than their immediate progenitors in vivo, even when forced to proliferate. Our analyses reveal that activation of stress response pathways drives both a global reduction of protein synthesis and altered translational programmes that together promote stem cell functions and tumorigenesis. Mechanistically, we show that inhibition of post-transcriptional cytosine-5 methylation locks tumour-initiating cells in this distinct translational inhibition programme. Paradoxically, this inhibition renders stem cells hypersensitive to cytotoxic stress, as tumour regeneration after treatment with 5-fluorouracil is blocked. Thus, stem cells must revoke translation inhibition pathways to regenerate a tissue or tumour.
Assuntos
Biossíntese de Proteínas , Células-Tronco/fisiologia , Estresse Fisiológico , Animais , Diferenciação Celular , Proliferação de Células/efeitos dos fármacos , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Transformação Celular Neoplásica/patologia , Citosina/metabolismo , Feminino , Fluoruracila/farmacologia , Folículo Piloso/citologia , Folículo Piloso/metabolismo , Humanos , Masculino , Metilação , Metiltransferases/deficiência , Metiltransferases/genética , Metiltransferases/metabolismo , Camundongos , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , RNA de Transferência/genética , RNA de Transferência/metabolismo , Regeneração , Neoplasias Cutâneas/metabolismo , Neoplasias Cutâneas/patologia , Células-Tronco/citologia , Estresse Fisiológico/genéticaRESUMO
Transcriptome plasticity, usually associated with alternative isoform generation, is recognised as a key mechanism driving proteomic diversity and biological complexity. Recent findings of Liscovitch-Brauer et al. and Ma et al. suggest that RNA base modifications are an additional central mode of transcriptome malleability that have the potential to determine evolutionary outcomes.
Assuntos
Proteômica , Transcriptoma , Adenosina/genética , Edição de RNARESUMO
Methyl-5-uridine (m5U) is one the most abundant non-canonical bases present in cellular RNA, and in yeast is found at position U54 of tRNAs where modification is catalysed by the methyltransferase Trm2. Although the mammalian enzymes that catalyse m5U formation are yet to be identified via experimental evidence, based on sequence homology to Trm2, two candidates currently exist, TRMT2A and TRMT2B. Here we developed a genome-wide single-nucleotide resolution mapping method, Fluorouracil-Induced-Catalytic-Crosslinking-Sequencing (FICC-Seq), in order to identify the relevant enzymatic targets. We demonstrate that TRMT2A is responsible for the majority of m5U present in human RNA, and that it commonly targets U54 of cytosolic tRNAs. By comparison to current methods, we show that FICC-Seq is a particularly robust method for accurate and reliable detection of relevant enzymatic target sites. Our associated finding of extensive irreversible TRMT2A-tRNA crosslinking in vivo following 5-Fluorouracil exposure is also intriguing, as it suggests a tangible mechanism for a previously suspected RNA-dependent route of Fluorouracil-mediated cytotoxicity.
Assuntos
Desoxirribonucleases/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , RNA/genética , Proteínas de Saccharomyces cerevisiae/genética , Uridina/genética , tRNA Metiltransferases/genética , Sobrevivência Celular/efeitos dos fármacos , Desoxirribonucleases/química , Fluoruracila/farmacologia , Células HEK293 , Humanos , RNA/química , RNA de Transferência , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/química , Uridina/química , Leveduras/genética , tRNA Metiltransferases/químicaRESUMO
Well over a hundred types of naturally occurring covalent modifications can be made to ribonucleotides in RNA molecules. Moreover, several types of such modifications are each known to be catalysed by multiple enzymes which largely appear to modify distinct sites within the cellular RNA. In order to aid functional investigations of such multi-enzyme RNA modification types in particular, it is important to determine which enzyme is responsible for catalysing modification at each site. Two methods, Aza-IP and methylation-iCLIP, were developed and used to map genome-wide locations of methyl-5-cytosine (m5C) RNA modifications inherently in an enzyme specific context. Though the methods are quite distinct, both rely on capturing catalytic intermediates of RNA m5C methyltransferases in a state where the cytosine undergoing methylation is covalently crosslinked to the enzyme. More recently the fundamental methylation-iCLIP principle has also been applied to map methyl-2-adenosine sites catalysed by the E. coli RlmN methylsynthase. Here I describe the ideas on which the two basic methods hinge, and summarise what has been achieved by them thus far. I also discuss whether and how such principles may be further exploited for profiling of other RNA modification types, such as methyl-5-uridine and pseudouridine.
Assuntos
Proteínas de Escherichia coli/metabolismo , Imunoprecipitação/métodos , Metiltransferases/metabolismo , Complexos Multienzimáticos/metabolismo , Processamento Pós-Transcricional do RNA , RNA Mensageiro/química , Transcriptoma , Animais , Azacitidina/química , Azacitidina/metabolismo , Biocatálise , Reagentes de Ligações Cruzadas/química , Proteínas de Escherichia coli/genética , Fluoruracila/química , Fluoruracila/metabolismo , Humanos , Metilação , Metiltransferases/genética , Complexos Multienzimáticos/genética , Pseudouridina/química , Pseudouridina/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Uridina/análogos & derivados , Uridina/química , Uridina/metabolismoRESUMO
Mutations in the cytosine-5 RNA methyltransferase NSun2 cause microcephaly and other neurological abnormalities in mice and human. How post-transcriptional methylation contributes to the human disease is currently unknown. By comparing gene expression data with global cytosine-5 RNA methylomes in patient fibroblasts and NSun2-deficient mice, we find that loss of cytosine-5 RNA methylation increases the angiogenin-mediated endonucleolytic cleavage of transfer RNAs (tRNA) leading to an accumulation of 5' tRNA-derived small RNA fragments. Accumulation of 5' tRNA fragments in the absence of NSun2 reduces protein translation rates and activates stress pathways leading to reduced cell size and increased apoptosis of cortical, hippocampal and striatal neurons. Mechanistically, we demonstrate that angiogenin binds with higher affinity to tRNAs lacking site-specific NSun2-mediated methylation and that the presence of 5' tRNA fragments is sufficient and required to trigger cellular stress responses. Furthermore, the enhanced sensitivity of NSun2-deficient brains to oxidative stress can be rescued through inhibition of angiogenin during embryogenesis. In conclusion, failure in NSun2-mediated tRNA methylation contributes to human diseases via stress-induced RNA cleavage.
Assuntos
Regulação da Expressão Gênica , Metiltransferases/metabolismo , Doenças do Sistema Nervoso/congênito , Doenças do Sistema Nervoso/patologia , RNA de Transferência/metabolismo , Animais , Encéfalo/patologia , Perfilação da Expressão Gênica , Humanos , Metilação , Metiltransferases/genética , Camundongos , Estresse Oxidativo , Ribonuclease Pancreático/metabolismoRESUMO
Causes of autosomal-recessive intellectual disability (ID) have, until very recently, been under researched because of the high degree of genetic heterogeneity. However, now that genome-wide approaches can be applied to single multiplex consanguineous families, the identification of genes harboring disease-causing mutations by autozygosity mapping is expanding rapidly. Here, we have mapped a disease locus in a consanguineous Pakistani family affected by ID and distal myopathy. We genotyped family members on genome-wide SNP microarrays and used the data to determine a single 2.5 Mb homozygosity-by-descent (HBD) locus in region 5p15.32-p15.31; we identified the missense change c.2035G>A (p.Gly679Arg) at a conserved residue within NSUN2. This gene encodes a methyltransferase that catalyzes formation of 5-methylcytosine at C34 of tRNA-leu(CAA) and plays a role in spindle assembly during mitosis as well as chromosome segregation. In mouse brains, we show that NSUN2 localizes to the nucleolus of Purkinje cells in the cerebellum. The effects of the mutation were confirmed by the transfection of wild-type and mutant constructs into cells and subsequent immunohistochemistry. We show that mutation to arginine at this residue causes NSUN2 to fail to localize within the nucleolus. The ID combined with a unique profile of comorbid features presented here makes this an important genetic discovery, and the involvement of NSUN2 highlights the role of RNA methyltransferase in human neurocognitive development.
Assuntos
Genes Recessivos , Deficiência Intelectual/genética , Metiltransferases/genética , RNA/genética , 5-Metilcitosina , Adolescente , Sequência de Aminoácidos , Animais , Povo Asiático/genética , Linhagem Celular Tumoral , Criança , Mapeamento Cromossômico , Modelos Animais de Doenças , Feminino , Heterogeneidade Genética , Genótipo , Homozigoto , Humanos , Deficiência Intelectual/fisiopatologia , Escore Lod , Masculino , Metiltransferases/metabolismo , Camundongos , Dados de Sequência Molecular , Paquistão , Linhagem , Polimorfismo de Nucleotídeo Único , RNA/metabolismoRESUMO
The protein predicted to be defective in individuals with Fanconi anemia complementation group J (FA-J), FANCJ, is a missing component in the Fanconi anemia pathway of genome maintenance. Here we identify pathogenic mutations in eight individuals with FA-J in the gene encoding the DEAH-box DNA helicase BRIP1, also called FANCJ. This finding is compelling evidence that the Fanconi anemia pathway functions through a direct physical interaction with DNA.
Assuntos
Cromossomos Humanos Par 17 , Proteínas de Ligação a DNA/deficiência , Proteínas de Ligação a DNA/genética , Anemia de Fanconi/genética , Mutação/genética , RNA Helicases/deficiência , RNA Helicases/genética , Proteínas de Grupos de Complementação da Anemia de Fanconi , Teste de Complementação Genética , Humanos , Repetições de Microssatélites , Dados de Sequência Molecular , Deleção de SequênciaRESUMO
The major molecular mode of action of the cytotoxic drug 5-fluorouracil (5-FU) is generally considered to result from thymidylate synthase inhibition. Recent findings relating to the function of the human uracil-5 methyltransferase (U5MT), TRMT2A, and its interaction with 5-FU metabolites incorporated within tRNAs, lead to an additional hypothesis that is proposed here.
Assuntos
Fluoruracila/farmacologia , Neoplasias/tratamento farmacológico , Reparo de DNA por Recombinação/efeitos dos fármacos , tRNA Metiltransferases/antagonistas & inibidores , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/genética , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Dano ao DNA , Fluoruracila/uso terapêutico , Humanos , Metilação/efeitos dos fármacos , Neoplasias/genética , RNA de Transferência/metabolismo , Uridina Trifosfato/análogos & derivados , Uridina Trifosfato/metabolismo , tRNA Metiltransferases/metabolismoRESUMO
Fanconi Anaemia (FA) is a cancer predisposition disorder characterized by spontaneous chromosome breakage and high cellular sensitivity to genotoxic agents. In response to DNA damage, a multi-subunit assembly of FA proteins, the FA core complex, monoubiquitinates the downstream FANCD2 protein. The FANCE protein plays an essential role in the FA process of DNA repair as the FANCD2-binding component of the FA core complex. Here we report a crystallographic and biological study of human FANCE. The first structure of a FA protein reveals the presence of a repeated helical motif that provides a template for the structural rationalization of other proteins defective in Fanconi Anaemia. The portion of FANCE defined by our crystallographic analysis is sufficient for interaction with FANCD2, yielding structural information into the mode of FANCD2 recruitment to the FA core complex. Disease-associated mutations disrupt the FANCE-FANCD2 interaction, providing structural insight into the molecular mechanisms of FA pathogenesis.
Assuntos
Proteína do Grupo de Complementação E da Anemia de Fanconi/química , Anemia de Fanconi/genética , Sequência de Aminoácidos , Cristalografia por Raios X , Proteína do Grupo de Complementação D2 da Anemia de Fanconi/química , Proteína do Grupo de Complementação D2 da Anemia de Fanconi/metabolismo , Proteína do Grupo de Complementação E da Anemia de Fanconi/genética , Proteína do Grupo de Complementação E da Anemia de Fanconi/metabolismo , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Estrutura Terciária de Proteína , Sequências Repetitivas de Aminoácidos , Alinhamento de Sequência , Técnicas do Sistema de Duplo-HíbridoRESUMO
A platform for highly parallel direct sequencing of native RNA strands was recently described by Oxford Nanopore Technologies, but despite initial efforts it remains crucial to further investigate the technology for quantification of complex transcriptomes. Here we undertake native RNA sequencing of polyA + RNA from two human cell lines, analysing ~5.2 million aligned native RNA reads. To enable informative comparisons, we also perform relevant ONT direct cDNA- and Illumina-sequencing. We find that while native RNA sequencing does enable some of the anticipated advantages, key unexpected aspects currently hamper its performance, most notably the quite frequent inability to obtain full-length transcripts from single reads, as well as difficulties to unambiguously infer their true transcript of origin. While characterising issues that need to be addressed when investigating more complex transcriptomes, our study highlights that with some defined improvements, native RNA sequencing could be an important addition to the mammalian transcriptomics toolbox.
Assuntos
Sequenciamento de Nucleotídeos em Larga Escala/métodos , Análise de Sequência de RNA/métodos , Transcriptoma/genética , Sequência de Bases/genética , Linhagem Celular , DNA Complementar/genética , Células HEK293 , Humanos , Poli A/genéticaRESUMO
Most methods for statistical analysis of RNA-seq data take a matrix of abundance estimates for some type of genomic features as their input, and consequently the quality of any obtained results is directly dependent on the quality of these abundances. Here, we present the junction coverage compatibility score, which provides a way to evaluate the reliability of transcript-level abundance estimates and the accuracy of transcript annotation catalogs. It works by comparing the observed number of reads spanning each annotated splice junction in a genomic region to the predicted number of junction-spanning reads, inferred from the estimated transcript abundances and the genomic coordinates of the corresponding annotated transcripts. We show that although most genes show good agreement between the observed and predicted junction coverages, there is a small set of genes that do not. Genes with poor agreement are found regardless of the method used to estimate transcript abundances, and the corresponding transcript abundances should be treated with care in any downstream analyses.
Assuntos
Genoma Humano/genética , Precursores de RNA/genética , RNA-Seq , Projetos de Pesquisa , Transcriptoma/genética , Regiões 3' não Traduzidas/genética , Confiabilidade dos Dados , Éxons/genética , Genes/genética , Biblioteca Genômica , Humanos , Íntrons/genética , Isoformas de Proteínas/genética , Reprodutibilidade dos TestesRESUMO
Fanconi anaemia is an inherited chromosomal instability disorder characterised by cellular sensitivity to DNA interstrand crosslinkers, bone-marrow failure and a high risk of cancer. Eleven FA genes have been identified, one of which, FANCD1, is the breast cancer susceptibility gene BRCA2. At least eight FA proteins form a nuclear core complex required for monoubiquitination of FANCD2. The BRCA2/FANCD1 protein is connected to the FA pathway by interactions with the FANCG and FANCD2 proteins, both of which co-localise with the RAD51 recombinase, which is regulated by BRCA2. These connections raise the question of whether any of the FANC proteins of the core complex might also participate in other complexes involved in homologous recombination repair. We therefore tested known FA proteins for direct interaction with RAD51 and its paralogs XRCC2 and XRCC3. FANCG was found to interact with XRCC3, and this interaction was disrupted by the FA-G patient derived mutation L71P. FANCG was co-immunoprecipitated with both XRCC3 and BRCA2 from extracts of human and hamster cells. The FANCG-XRCC3 and FANCG-BRCA2 interactions did not require the presence of other FA proteins from the core complex, suggesting that FANCG also participates in a DNA repair complex that is downstream and independent of FANCD2 monoubiquitination. Additionally, XRCC3 and BRCA2 proteins co-precipitate in both human and hamster cells and this interaction requires FANCG. The FANCG protein contains multiple tetratricopeptide repeat motifs (TPRs), which function as scaffolds to mediate protein-protein interactions. Mutation of one or more of these motifs disrupted all of the known interactions of FANCG. We propose that FANCG, in addition to stabilising the FA core complex, may have a role in building multiprotein complexes that facilitate homologous recombination repair.
Assuntos
Proteína BRCA2/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteína do Grupo de Complementação G da Anemia de Fanconi/metabolismo , Motivos de Aminoácidos , Animais , Proteína BRCA2/genética , Células COS , Linhagem Celular , Chlorocebus aethiops , Cricetinae , Reparo do DNA , Proteínas de Ligação a DNA/genética , Anemia de Fanconi/genética , Anemia de Fanconi/metabolismo , Proteína do Grupo de Complementação G da Anemia de Fanconi/química , Proteína do Grupo de Complementação G da Anemia de Fanconi/genética , Células HeLa , Humanos , Técnicas In Vitro , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Recombinação Genética , Técnicas do Sistema de Duplo-HíbridoRESUMO
Background: The ability to obtain long read lengths during DNA sequencing has several potentially important practical applications. Especially long read lengths have been reported using the Nanopore sequencing method, currently commercially available from Oxford Nanopore Technologies (ONT). However, early reports have demonstrated only limited levels of combined throughput and sequence accuracy. Recently, ONT released a new CsgG pore sequencing system as well as a 250b/s translocation chemistry with potential for improvements. Methods: We made use of such components on ONTs miniature 'MinION' device and sequenced native genomic DNA obtained from the near haploid cancer cell line HAP1. Analysis of our data was performed utilising recently described computational tools tailored for nanopore/long-read sequencing outputs, and here we present our key findings. Results: From a single sequencing run, we obtained ~240,000 high-quality mapped reads, comprising a total of ~2.3 billion bases. A mean read length of 9.6kb and an N50 of ~17kb was achieved, while sequences mapped to reference with a mean identity of 85%. Notably, we obtained ~68X coverage of the mitochondrial genome and were able to achieve a mean consensus identity of 99.8% for sequenced mtDNA reads. Conclusions: With improved sequencing chemistries already released and higher-throughput instruments in the pipeline, this early study suggests that ONT CsgG-based sequencing may be a useful option for potential practical long-read applications.
RESUMO
Next-generation sequencing technologies have enabled the transcriptome to be profiled at a previously unprecedented speed and depth. This yielded insights into fundamental transcriptomic processes such as gene transcription, RNA processing, and mRNA splicing. Immunoprecipitation-based transcriptomic methods such as individual nucleotide resolution crosslinking immunoprecipitation (iCLIP) have also allowed high-resolution analysis of the RNA interactions of a protein of interest, thus revealing new regulatory mechanisms. We and others have recently modified this method to profile RNA methylation, and we refer to this customized technique as methylation-iCLIP (miCLIP). Variants of miCLIP have been used to map the methyl-5-cytosine (m5C) or methyl-6-adenosine (m6A) modification at nucleotide resolution in the human transcriptome. Here we describe the m5C-miCLIP protocol, discuss how it yields the nucleotide-resolution RNA modification maps, and comment on how these have contributed to the new field of molecular genetics research coined "epitranscriptomics."
Assuntos
Epigênese Genética , Epigenômica , Imunoprecipitação , RNA/genética , Transcriptoma , Linhagem Celular , Epigenômica/métodos , Perfilação da Expressão Gênica , Biblioteca Gênica , Humanos , Imunoprecipitação/métodos , Marcação por Isótopo , Metilação , RNA/químicaRESUMO
Epitranscriptome modifications are required for structure and function of RNA and defects in these pathways have been associated with human disease. Here we identify the RNA target for the previously uncharacterized 5-methylcytosine (m(5)C) methyltransferase NSun3 and link m(5)C RNA modifications with energy metabolism. Using whole-exome sequencing, we identified loss-of-function mutations in NSUN3 in a patient presenting with combined mitochondrial respiratory chain complex deficiency. Patient-derived fibroblasts exhibit severe defects in mitochondrial translation that can be rescued by exogenous expression of NSun3. We show that NSun3 is required for deposition of m(5)C at the anticodon loop in the mitochondrially encoded transfer RNA methionine (mt-tRNA(Met)). Further, we demonstrate that m(5)C deficiency in mt-tRNA(Met) results in the lack of 5-formylcytosine (f(5)C) at the same tRNA position. Our findings demonstrate that NSUN3 is necessary for efficient mitochondrial translation and reveal that f(5)C in human mitochondrial RNA is generated by oxidative processing of m(5)C.
Assuntos
Regulação da Expressão Gênica , Metiltransferases/metabolismo , Mitocôndrias/metabolismo , Doenças Mitocondriais/genética , RNA de Transferência/metabolismo , Células HEK293 , Células HeLa , Humanos , Metilação , Metiltransferases/genética , MutaçãoRESUMO
Some common diseases are known to have an inherited component, however, their population- and familial-incidence patterns do not conform to any known monogenic Mendelian pattern of inheritance and instead they are currently much better explained if an underlying polygenic architecture is posited. Studies that have attempted to identify the causative genetic factors have been designed on this polygenic framework, but so far the yield has been largely unsatisfactory. Based on accumulating recent observations concerning the roles of somatic mosaicism in disease, in this article a second framework which posits a single gene-two hit model which can be modulated by a mutator/anti-mutator genetic background is suggested. I discuss whether such a model can be considered a viable alternative based on current knowledge, its advantages over the current polygenic framework, and describe practical routes via which the new framework can be investigated.