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Genes Dev ; 35(13-14): 1005-1019, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-34168039


N6-methyladenosine (m6A) is an abundant internal RNA modification, influencing transcript fate and function in uninfected and virus-infected cells. Installation of m6A by the nuclear RNA methyltransferase METTL3 occurs cotranscriptionally; however, the genomes of some cytoplasmic RNA viruses are also m6A-modified. How the cellular m6A modification machinery impacts coronavirus replication, which occurs exclusively in the cytoplasm, is unknown. Here we show that replication of SARS-CoV-2, the agent responsible for the COVID-19 pandemic, and a seasonal human ß-coronavirus HCoV-OC43, can be suppressed by depletion of METTL3 or cytoplasmic m6A reader proteins YTHDF1 and YTHDF3 and by a highly specific small molecule METTL3 inhibitor. Reduction of infectious titer correlates with decreased synthesis of viral RNAs and the essential nucleocapsid (N) protein. Sites of m6A modification on genomic and subgenomic RNAs of both viruses were mapped by methylated RNA immunoprecipitation sequencing (meRIP-seq). Levels of host factors involved in m6A installation, removal, and recognition were unchanged by HCoV-OC43 infection; however, nuclear localization of METTL3 and cytoplasmic m6A readers YTHDF1 and YTHDF2 increased. This establishes that coronavirus RNAs are m6A-modified and host m6A pathway components control ß-coronavirus replication. Moreover, it illustrates the therapeutic potential of targeting the m6A pathway to restrict coronavirus reproduction.

Coronavirus Humano OC43/fisiologia , Processamento Pós-Transcricional do RNA/genética , SARS-CoV-2/fisiologia , Replicação Viral/genética , Adenosina/análogos & derivados , Adenosina/genética , Adenosina/metabolismo , Linhagem Celular , Infecções por Coronavirus/metabolismo , Infecções por Coronavirus/virologia , Regulação da Expressão Gênica/efeitos dos fármacos , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Humanos , Metiltransferases/antagonistas & inibidores , Metiltransferases/metabolismo , Proteínas do Nucleocapsídeo , RNA Viral/metabolismo , Proteínas de Ligação a RNA/metabolismo , Replicação Viral/efeitos dos fármacos
PLoS One ; 10(12): e0144444, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26689548


The transcription factor STAT1 plays a central role in orchestrating responses to various pathogens by activating the transcription of nuclear-encoded genes that mediate the antiviral, the antigrowth, and immune surveillance effects of interferons and other cytokines. In addition to regulating gene expression, we report that STAT1-/- mice display increased energy expenditure and paradoxically decreased release of triglycerides from white adipose tissue (WAT). Liver mitochondria from STAT1-/- mice show both defects in coupling of the electron transport chain (ETC) and increased numbers of mitochondria. Consistent with elevated numbers of mitochondria, STAT1-/- mice expressed increased amounts of PGC1α, a master regulator of mitochondrial biogenesis. STAT1 binds to the PGC1α promoter in fed mice but not in fasted animals, suggesting that STAT1 inhibited transcription of PGC1α. Since STAT1-/- mice utilized more lipids we examined white adipose tissue (WAT) stores. Contrary to expectations, fasted STAT1-/- mice did not lose lipid from WAT. ß-adrenergic stimulation of glycerol release from isolated STAT1-/- WAT was decreased, while activation of hormone sensitive lipase was not changed. These findings suggest that STAT1-/- adipose tissue does not release glycerol and that free fatty acids (FFA) re-esterify back to triglycerides, thus maintaining fat mass in fasted STAT1-/- mice.

Adipócitos/metabolismo , Ácidos Graxos/metabolismo , Mitocôndrias Hepáticas/metabolismo , Fator de Transcrição STAT1/metabolismo , Animais , Complexo de Proteínas da Cadeia de Transporte de Elétrons/genética , Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Ácidos Graxos/genética , Camundongos , Camundongos Knockout , Mitocôndrias Hepáticas/genética , Oxirredução , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Elementos de Resposta , Fator de Transcrição STAT1/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Triglicerídeos/genética , Triglicerídeos/metabolismo
Proc Natl Acad Sci U S A ; 111(49): 17450-5, 2014 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-25422441


Anabolic and catabolic signaling oppose one another in adipose tissue to maintain cellular and organismal homeostasis, but these pathways are often dysregulated in metabolic disorders. Although it has long been established that stimulation of the ß-adrenergic receptor inhibits insulin-stimulated glucose uptake in adipocytes, the mechanism has remained unclear. Here we report that ß-adrenergic-mediated inhibition of glucose uptake requires lipolysis. We also show that lipolysis suppresses glucose uptake by inhibiting the mammalian target of rapamycin (mTOR) complexes 1 and 2 through complex dissociation. In addition, we show that products of lipolysis inhibit mTOR through complex dissociation in vitro. These findings reveal a previously unrecognized intracellular signaling mechanism whereby lipolysis blocks the phosphoinositide 3-kinase-Akt-mTOR pathway, resulting in decreased glucose uptake. This previously unidentified mechanism of mTOR regulation likely contributes to the development of insulin resistance.

Adipócitos/citologia , Catecolaminas/química , Glucose/farmacocinética , Lipólise/fisiologia , Serina-Treonina Quinases TOR/metabolismo , Células 3T3-L1 , Animais , AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Homeostase , Hiperglicemia/metabolismo , Insulina/metabolismo , Resistência à Insulina , Lipídeos/química , Camundongos , Modelos Biológicos , Naftiridinas/metabolismo , Receptores Adrenérgicos beta/metabolismo , Transdução de Sinais