RESUMEN
RNA surveillance systems degrade aberrant RNAs that result from defective transcriptional termination, splicing, and polyadenylation. Defective RNAs in the nucleus are recognized by RNA-binding proteins and MTR4, and are degraded by the RNA exosome complex. Here, we detect aberrant RNAs in MTR4-depleted cells using long-read direct RNA sequencing and 3' sequencing. MTR4 destabilizes intronic polyadenylated transcripts generated by transcriptional read-through over one or more exons, termed 3' eXtended Transcripts (3XTs). MTR4 also associates with hnRNPK, which recognizes 3XTs with multiple exons. Moreover, the aberrant protein translated from KCTD13 3XT is a target of the hnRNPK-MTR4-RNA exosome pathway and forms aberrant condensates, which we name KCTD13 3eXtended Transcript-derived protein (KeXT) bodies. Our results suggest that RNA surveillance in human cells inhibits the formation of condensates of a defective polyadenylated transcript-derived protein.
Asunto(s)
Exones , Ribonucleoproteína Heterogénea-Nuclear Grupo K , ARN Mensajero , Proteínas de Unión al ARN , Humanos , Exones/genética , Ribonucleoproteína Heterogénea-Nuclear Grupo K/metabolismo , Ribonucleoproteína Heterogénea-Nuclear Grupo K/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/metabolismo , Proteínas de Unión al ARN/genética , Células HeLa , Células HEK293 , Complejo Multienzimático de Ribonucleasas del Exosoma/metabolismo , Complejo Multienzimático de Ribonucleasas del Exosoma/genética , Poliadenilación , Proteínas de Transporte Nucleocitoplasmático/genética , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Intrones/genética , ARN NucleotidiltransferasasRESUMEN
Mammalian genomes encode large number of long noncoding RNAs (lncRNAs) that play key roles in various biological processes, including proliferation, differentiation, and stem cell pluripotency. Recent studies have addressed that some lncRNAs are dysregulated in human cancers and may play crucial roles in tumor development and progression. Here, we show that the lncRNA ZNNT1 is required for the proliferation and tumorigenicity of colon cancer cells with wild-type p53. ZNNT1 knockdown leads to decreased ubiquitination and stabilization of p53 protein. Moreover, we demonstrate that ZNNT1 needs to interact with SART3 to destabilize p53 and to promote the proliferation and tumorigenicity of colon cancer cells. We further show that SART3 is associated with the ubiquitin-specific peptidase USP15 and that ZNNT1 may induce p53 destabilization by inhibiting this interaction. These results suggest that ZNNT1 interferes with the SART3-USP15 complex-mediated stabilization of p53 protein and thereby plays important roles in the proliferation and tumorigenicity of colon cancer cells. Our findings suggest that ZNNT1 may be a promising molecular target for the therapy of colon cancer.