RESUMO
BACKGROUND: Due to insufficient knowledge about key molecular events, Hepatocellular carcinoma (HCC) lacks effective treatment targets. Spliceosome-related genes were significantly altered in HCC. Oncofetal proteins are ideal tumor therapeutic targets. Screening of differentially expressed Spliceosome-related oncofetal protein in embryonic liver development and HCC helps discover effective therapeutic targets for HCC. METHODS: Differentially expressed spliceosome genes were analysis in fetal liver and HCC through bioinformatics analysis. Small nuclear ribonucleoprotein polypeptide E (SNRPE) expression was detected in fetal liver, adult liver and HCC tissues. The role of SNRPE in HCC was performed multiple assays in vitro and in vivo. SNRPE-regulated alternative splicing was recognized by RNA-Seq and confirmed by multiple assays. RESULTS: We herein identified SNRPE as a crucial oncofetal splicing factor, significantly associated with the adverse prognosis of HCC. SOX2 was identified as the activator for SNRPE reactivation. Efficient knockdown of SNRPE resulted in the complete cessation of HCC tumorigenesis and progression. Mechanistically, SNRPE knockdown reduced FGFR4 mRNA expression by triggering nonsense-mediated RNA decay. A partial inhibition of SNRPE-induced malignant progression of HCC cells was observed upon FGFR4 knockdown. CONCLUSIONS: Our findings highlight SNRPE as a novel oncofetal splicing factor and shed light on the intricate relationship between oncofetal splicing factors, splicing events, and carcinogenesis. Consequently, SNRPE emerges as a potential therapeutic target for HCC treatment. Model of oncofetal SNRPE promotes HCC tumorigenesis by regulating the AS of FGFR4 pre-mRNA.
Assuntos
Processamento Alternativo , Carcinogênese , Carcinoma Hepatocelular , Neoplasias Hepáticas , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos , Animais , Humanos , Camundongos , Carcinogênese/genética , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/metabolismo , Camundongos Nus , Prognóstico , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/genética , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/metabolismoRESUMO
Molybdenum cofactor (Moco) biosynthesis is a complex process that involves the coordinated function of several proteins. In the recent years it has become evident that the availability of Fe-S clusters play an important role for the biosynthesis of Moco. First, the MoaA protein binds two [4Fe-4S] clusters per monomer. Second, the expression of the moaABCDE and moeAB operons is regulated by FNR, which senses the availability of oxygen via a functional [4Fe-4S] cluster. Finally, the conversion of cyclic pyranopterin monophosphate to molybdopterin requires the availability of the L-cysteine desulfurase IscS, which is an enzyme involved in the transfer of sulfur to various acceptor proteins with a main role in the assembly of Fe-S clusters. In this review, we dissect the dependence of the production of active molybdoenzymes in detail, starting from the regulation of gene expression and further explaining sulfur delivery and Fe-S cluster insertion into target enzymes. Further, Fe-S cluster assembly is also linked to iron availability. While the abundance of selected molybdoenzymes is largely decreased under iron-limiting conditions, we explain that the expression of the genes is dependent on an active FNR protein. FNR is a very important transcription factor that represents the master-switch for the expression of target genes in response to anaerobiosis. Moco biosynthesis is further directly dependent on the presence of ArcA and also on an active Fur protein.
Assuntos
Coenzimas , Proteínas Ferro-Enxofre , Metaloproteínas , Cofatores de Molibdênio , Pteridinas , Metaloproteínas/metabolismo , Metaloproteínas/genética , Metaloproteínas/biossíntese , Proteínas Ferro-Enxofre/metabolismo , Proteínas Ferro-Enxofre/genética , Coenzimas/metabolismo , Coenzimas/biossíntese , Coenzimas/genética , Pteridinas/metabolismo , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Ferro/metabolismo , Enxofre/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Liases de Carbono-Enxofre/metabolismo , Liases de Carbono-Enxofre/genética , Regulação Bacteriana da Expressão Gênica , Óperon , IsomerasesRESUMO
The expression of most molybdoenzymes in Escherichia coli has so far been revealed to be regulated by anaerobiosis and requires the presence of iron, based on the necessity of the transcription factor FNR to bind one [4Fe-4S] cluster. One exception is trimethylamine-N-oxide reductase encoded by the torCAD operon, which has been described to be expressed independently from FNR. In contrast to other alternative anaerobic respiratory systems, the expression of the torCAD operon was shown not to be completely repressed by the presence of dioxygen. To date, the basis for the O2-dependent expression of the torCAD operon has been related to the abundance of the transcriptional regulator IscR, which represses the transcription of torS and torT, and is more abundant under aerobic conditions than under anaerobic conditions. In this study, we reinvestigated the regulation of the torCAD operon and its dependence on the presence of iron and identified a novel regulation that depends on the presence of the bis-molybdopterin guanine dinucleotide (bis-MGD) molybdenum cofactor . We confirmed that the torCAD operon is directly regulated by the heme-containing protein TorC and is indirectly regulated by ArcA and by the availability of iron via active FNR and Fur, both regulatory proteins that influence the synthesis of the molybdenum cofactor. Furthermore, we identified a novel regulation mode of torCAD expression that is dependent on cellular levels of bis-MGD and is not used by other bis-MGD-containing enzymes like nitrate reductase.IMPORTANCEIn bacteria, molybdoenzymes are crucial for anaerobic respiration using alternative electron acceptors. FNR is a very important transcription factor that represents the master switch for the expression of target genes in response to anaerobiosis. Only Escherichia coli trimethylamine-N-oxide (TMAO) reductase escapes this regulation by FNR. We identified that the expression of TMAO reductase is regulated by the amount of bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor synthesized by the cell itself, representing a novel regulation pathway for the expression of an operon coding for a molybdoenzyme. Furthermore, TMAO reductase gene expression is indirectly regulated by the presence of iron, which is required for the production of the bis-MGD cofactor in the cell.