RESUMO
MicroRNA (miRNA) processing is a critical step in mature miRNA production. Its dysregulation leads to an increase in miRNA isoforms with heterogenous 5'-ends (isomiRs), which can recognize distinct target sites because of their shifted seed sequence. Although some miRNA genes display productive expression of their 5'-isomiRs in cancers, how their production is controlled and how 5'-isomiRs affect tumor progression have yet to be explored. In this study, based on integrative analyses of high-throughput sequencing data produced by our group and publicly available data, we demonstrate that primary miR-21 (pri-miR-21) is processed into the cancer-specific isomiR isomiR-21-5p | ±1, which suppresses growth hormone receptor (GHR) in liver cancer. Treatment with antagomirs against isomiR-21-5p | ±1 inhibited the in vitro tumorigenesis of liver cancer cells and allowed the recovery of GHR, whereas the introduction of isomiR-21-5p | ±1 mimics attenuated these effects. These effects were validated in a mouse model of spontaneous liver cancer. Heterogeneous nuclear ribonucleoprotein C and U2 small nuclear RNA auxiliary factor 2 were predicted to bind upstream of pre-miR-21 via a poly-(U) motif and influence Drosha processing to induce the production of isomiR-21-5p | ±1. Our findings suggest an oncogenic function for the non-canonical isomiR-21-5p | ±1 in liver cancer, and its production was shown to be regulated by hnRNPC.
Assuntos
Ribonucleoproteínas Nucleares Heterogêneas Grupo C , MicroRNAs , Animais , Ribonucleoproteínas Nucleares Heterogêneas Grupo C/genética , Ribonucleoproteínas Nucleares Heterogêneas Grupo C/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Neoplasias Hepáticas Experimentais/genética , Neoplasias Hepáticas Experimentais/metabolismo , Neoplasias Hepáticas Experimentais/patologia , Camundongos , MicroRNAs/genética , MicroRNAs/metabolismo , Isoformas de Proteínas , Processamento Pós-Transcricional do RNARESUMO
The stability and quality of metazoan mRNAs are under microRNA (miRNA)-mediated and nonsense-mediated control. Although UPF1, a core mediator of nonsense-mediated mRNA decay (NMD), mediates the decay of target mRNA in a 3'UTR-length-dependent manner, the detailed mechanism remains unclear. Here, we suggest that 3'UTR-length-dependent mRNA decay is not mediated by nonsense mRNAs but rather by miRNAs that downregulate target mRNAs via Ago-associated UPF1/SMG7. Global analyses of mRNAs in response to UPF1 RNA interference in miRNA-deficient cells reveal that 3'UTR-length-dependent mRNA decay by UPF1 requires canonical miRNA targeting. The destabilization of miRNA targets is accomplished by the combination of Ago2 and UPF1/SMG7, which may recruit the CCR4-NOT deadenylase complex. Indeed, loss of the SMG7-deadenylase complex interaction increases the levels of transcripts regulated by UPF1-SMG7. This UPF1/SMG7-dependent miRNA-mediated mRNA decay pathway may enable miRNA targeting to become more predictable and expand the miRNA-mRNA regulatory network.
Assuntos
Proteínas de Transporte/metabolismo , Biologia Computacional/métodos , MicroRNAs/metabolismo , RNA Helicases/metabolismo , Estabilidade de RNA/fisiologia , Transativadores/metabolismo , Regiões 3' não Traduzidas/genética , Animais , Western Blotting , Proteínas de Transporte/genética , Regulação da Expressão Gênica/genética , Regulação da Expressão Gênica/fisiologia , Células HeLa , Humanos , Camundongos , MicroRNAs/genética , RNA Helicases/genética , Interferência de RNA/fisiologia , Estabilidade de RNA/genética , Transativadores/genéticaRESUMO
All metazoan mRNAs have a poly(A) tail at the 3' end with the exception of replication-dependent histone (RDH) mRNAs, which end in a highly conserved stem-loop (SL) structure. However, a subset of RDH mRNAs are reported to be polyadenylated under physiologic conditions. The molecular details of the biogenesis of polyadenylated RDH [poly(A)+ RDH] mRNAs remain unknown. In this study, our genome-wide analyses reveal that puromycin treatment or UVC irradiation stabilizes poly(A)+ RDH mRNAs, relative to canonical RDH mRNAs, which end in an SL structure. We demonstrate that the stabilization of poly(A)+ RDH mRNAs occurs in a translation-independent manner and is regulated via human antigen R (HuR) binding to the extended 3' UTR under stress conditions. Our data suggest that HuR regulates the expression of poly(A)+ RDH mRNAs.-Ryu, I., Park, Y., Seo, J.-W., Park, O. H., Ha, H., Nam, J.-W., Kim, Y. K. HuR stabilizes a polyadenylated form of replication-dependent histone mRNAs under stress conditions.
