RESUMO
Viral infection perturbs host cells and can be used to uncover regulatory mechanisms controlling cellular responses and susceptibility to infections. Using cell biological, biochemical, and genetic tools, we reveal that influenza A virus (IAV) infection induces global transcriptional defects at the 3' ends of active host genes and RNA polymerase II (RNAPII) run-through into extragenic regions. Deregulated RNAPII leads to expression of aberrant RNAs (3' extensions and host-gene fusions) that ultimately cause global transcriptional downregulation of physiological transcripts, an effect influencing antiviral response and virulence. This phenomenon occurs with multiple strains of IAV, is dependent on influenza NS1 protein, and can be modulated by SUMOylation of an intrinsically disordered region (IDR) of NS1 expressed by the 1918 pandemic IAV strain. Our data identify a strategy used by IAV to suppress host gene expression and indicate that polymorphisms in IDRs of viral proteins can affect the outcome of an infection.
Assuntos
Influenza Humana/genética , RNA Polimerase II/genética , Regiões Terminadoras Genéticas/genética , Humanos , Vírus da Influenza A/patogenicidade , Vírus da Influenza A/fisiologia , VirulênciaRESUMO
N6-methyl-adenosine (m(6)A) is the most abundant modification on messenger RNAs and is linked to human diseases, but its functions in mammalian development are poorly understood. Here we reveal the evolutionary conservation and function of m(6)A by mapping the m(6)A methylome in mouse and human embryonic stem cells. Thousands of messenger and long noncoding RNAs show conserved m(6)A modification, including transcripts encoding core pluripotency transcription factors. m(6)A is enriched over 3' untranslated regions at defined sequence motifs and marks unstable transcripts, including transcripts turned over upon differentiation. Genetic inactivation or depletion of mouse and human Mettl3, one of the m(6)A methylases, led to m(6)A erasure on select target genes, prolonged Nanog expression upon differentiation, and impaired ESC exit from self-renewal toward differentiation into several lineages in vitro and in vivo. Thus, m(6)A is a mark of transcriptome flexibility required for stem cells to differentiate to specific lineages.
Assuntos
Adenina/análogos & derivados , Células-Tronco Embrionárias/fisiologia , Proteínas de Homeodomínio/metabolismo , Metiltransferases/metabolismo , Adenina/metabolismo , Animais , Sequência de Bases , Diferenciação Celular/genética , Linhagem Celular , Linhagem da Célula/genética , Proliferação de Células/genética , Sequência Conservada/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Homeodomínio/genética , Humanos , Metiltransferases/genética , Camundongos , Camundongos SCID , Dados de Sequência Molecular , Mutação/genética , Proteína Homeobox Nanog , Processamento Pós-Transcricional do RNA/genética , RNA Interferente Pequeno/genética , TranscriptomaRESUMO
Patients with recessive dystrophic epidermolysis bullosa (RDEB) lack functional type VII collagen owing to mutations in the gene COL7A1 and suffer severe blistering and chronic wounds that ultimately lead to infection and development of lethal squamous cell carcinoma. The discovery of induced pluripotent stem cells (iPSCs) and the ability to edit the genome bring the possibility to provide definitive genetic therapy through corrected autologous tissues. We generated patient-derived COL7A1-corrected epithelial keratinocyte sheets for autologous grafting. We demonstrate the utility of sequential reprogramming and adenovirus-associated viral genome editing to generate corrected iPSC banks. iPSC-derived keratinocytes were produced with minimal heterogeneity, and these cells secreted wild-type type VII collagen, resulting in stratified epidermis in vitro in organotypic cultures and in vivo in mice. Sequencing of corrected cell lines before tissue formation revealed heterogeneity of cancer-predisposing mutations, allowing us to select COL7A1-corrected banks with minimal mutational burden for downstream epidermis production. Our results provide a clinical platform to use iPSCs in the treatment of debilitating genodermatoses, such as RDEB.
Assuntos
Colágeno Tipo VII/genética , Colágeno Tipo VII/uso terapêutico , Epidermólise Bolhosa Distrófica/terapia , Genes Recessivos , Células-Tronco Pluripotentes Induzidas/metabolismo , Células-Tronco Pluripotentes Induzidas/transplante , Animais , Sequência de Bases , Epidermólise Bolhosa Distrófica/genética , Predisposição Genética para Doença , Terapia Genética , Genoma Humano , Recombinação Homóloga/genética , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Queratinócitos/patologia , Camundongos , Dados de Sequência Molecular , Mutação/genética , Análise de Sequência de DNARESUMO
The combination of induced pluripotent stem cell (iPSC) technology and targeted gene modification by homologous recombination (HR) represents a promising new approach to generate genetically corrected, patient-derived cells that could be used for autologous transplantation therapies. This strategy has several potential advantages over conventional gene therapy including eliminating the need for immunosuppression, avoiding the risk of insertional mutagenesis by therapeutic vectors, and maintaining expression of the corrected gene by endogenous control elements rather than a constitutive promoter. However, gene targeting in human pluripotent cells has remained challenging and inefficient. Recently, engineered zinc finger nucleases (ZFNs) have been shown to substantially increase HR frequencies in human iPSCs, raising the prospect of using this technology to correct disease causing mutations. Here, we describe the generation of iPSC lines from sickle cell anemia patients and in situ correction of the disease causing mutation using three ZFN pairs made by the publicly available oligomerized pool engineering method (OPEN). Gene-corrected cells retained full pluripotency and a normal karyotype following removal of reprogramming factor and drug-resistance genes. By testing various conditions, we also demonstrated that HR events in human iPSCs can occur as far as 82 bps from a ZFN-induced break. Our approach delineates a roadmap for using ZFNs made by an open-source method to achieve efficient, transgene-free correction of monogenic disease mutations in patient-derived iPSCs. Our results provide an important proof of principle that ZFNs can be used to produce gene-corrected human iPSCs that could be used for therapeutic applications.
