RESUMEN
The nuclear RNA exosome is an essential multi-subunit complex that controls RNA homeostasis. Congenital mutations in RNA exosome genes are associated with neurodegenerative diseases. Little is known about the role of the RNA exosome in the cellular response to pathogens. Here, using NGS and human and mouse genetics, we show that influenza A virus (IAV) ribogenesis and growth are suppressed by impaired RNA exosome activity. Mechanistically, the nuclear RNA exosome coordinates the initial steps of viral transcription with RNAPII at host promoters. The viral polymerase complex co-opts the nuclear RNA exosome complex and cellular RNAs en route to 3' end degradation. Exosome deficiency uncouples chromatin targeting of the viral polymerase complex and the formation of cellular:viral RNA hybrids, which are essential RNA intermediates that license transcription of antisense genomic viral RNAs. Our results suggest that evolutionary arms races have shaped the cellular RNA quality control machinery.
Asunto(s)
Interacciones Huésped-Patógeno , Subtipo H1N1 del Virus de la Influenza A/fisiología , Subtipo H3N2 del Virus de la Influenza A/fisiología , Gripe Humana/virología , ARN Polimerasa II/metabolismo , Células A549 , Animales , Inmunoprecipitación de Cromatina , Exorribonucleasas/genética , Complejo Multienzimático de Ribonucleasas del Exosoma/genética , Exosomas/metabolismo , Humanos , Espectrometría de Masas , Ratones , Mutación , Enfermedades Neurodegenerativas/virología , Proteínas de Unión al ARN/genética , Ribosomas/genética , Transcripción GenéticaRESUMEN
N6-methyladenosine modification (m6A) fine-tunes RNA fate in a variety of ways, thus regulating multiple fundamental biological processes. m6A writers bind to chromatin and interact with RNA polymerase II (RNAPII) during transcription. To evaluate how the dynamics of the transcription process impact m6A deposition, we studied RNAPII elongation rates in mouse embryonic stem cells with altered chromatin configurations, due to reductions in linker histone H1 content. We found that genes transcribed at slow speed are preferentially methylated and display unique signatures at their promoter region, namely high levels of histone H1, together with marks of bivalent chromatin and low RNAPII pausing. They are also highly susceptible to m6A loss upon histone H1 reduction. These results indicate that RNAPII velocity links chromatin structure and the deposition of m6A, highlighting the intricate relationship between different regulatory layers on nascent mRNA molecules.
Asunto(s)
Histonas , ARN Polimerasa II , Animales , Cromatina/genética , Histonas/genética , Histonas/metabolismo , Ratones , Regiones Promotoras Genéticas , ARN Polimerasa II/genética , ARN Polimerasa II/metabolismo , ARN Mensajero/genéticaRESUMEN
The ability of elongating RNA polymerase II (RNAPII) to regulate the nucleosome barrier is poorly understood because we do not know enough about the involved factors and we lack a conceptual framework to model this process. Our group recently identified the conserved Fun30/SMARCAD1 family chromatin-remodeling factor, Fun30Fft3, as being critical for relieving the nucleosome barrier during RNAPII-mediated elongation, and proposed a model illustrating how Fun30Fft3 may contribute to nucleosome disassembly during RNAPII-mediated elongation. Here, we present a model that describes nucleosome dynamics during RNAPII-mediated elongation in mathematical terms and addresses the involvement of Fun30Fft3 in this process.