Read-through circular RNA rt-circ-HS promotes hypoxia inducible factor 1α expression and renal carcinoma cell proliferation, migration and invasiveness / 北京大学学报(医学版)

OBJECTIVE@#To identify and characterize read-through RNAs and read-through circular RNAs (rt-circ-HS) derived from transcriptional read-through hypoxia inducible factor 1α (HIF1α) and small nuclear RNA activating complex polypeptide 1 (SNAPC1) the two adjacent genes located on chromosome 14q23, in renal carcinoma cells and renal carcinoma tissues, and to study the effects of rt-circ-HS on biological behavior of renal carcinoma cells and on regulation of HIF1α.@*METHODS@#Reverse transcription-polymerase chain reaction (RT-PCR) and Sanger sequencing were used to examine expression of read-through RNAs HIF1α-SNAPC1 and rt-circ-HS in different tumor cells. Tissue microarrays of 437 different types of renal cell carcinoma (RCC) were constructed, and chromogenic in situ hybridization (ISH) was used to investigate expression of rt-circ-HS in different RCC types. Small interference RNA (siRNA) and artificial overexpression plasmids were designed to examine the effects of rt-circ-HS on 786-O and A498 renal carcinoma cell proliferation, migration and invasiveness by cell counting kit 8 (CCK8), EdU incorporation and Transwell cell migration and invasion assays. RT-PCR and Western blot were used to exa-mine expression of HIF1α and SNAPC1 RNA and proteins after interference of rt-circ-HS with siRNA, respectively. The binding of rt-circ-HS with microRNA 539 (miR-539), and miR-539 with HIF1α 3' untranslated region (3' UTR), and the effects of these interactions were investigated by dual luciferase reporter gene assays.@*RESULTS@#We discovered a novel 1 144 nt rt-circ-HS, which was derived from read-through RNA HIF1α-SNAPC1 and consisted of HIF1α exon 2-6 and SNAPC1 exon 2-4. Expression of rt-circ-HS was significantly upregulated in 786-O renal carcinoma cells. ISH showed that the overall positive expression rate of rt-circ-HS in RCC tissue samples was 67.5% (295/437), and the expression was different in different types of RCCs. Mechanistically, rt-circ-HS promoted renal carcinoma cell proliferation, migration and invasiveness by functioning as a competitive endogenous inhibitor of miR-539, which we found to be a potent post-transcriptional suppressor of HIF1α, thus promoting expression of HIF1α.@*CONCLUSION@#The novel rt-circ-HS is highly expressed in different types of RCCs and acts as a competitive endogenous inhibitor of miR-539 to promote expression of its parental gene HIF1α and thus the proliferation, migration and invasion of renal cancer cells.

Avances terapéuticos en errores innatos del metabolismo: pequeñas moléculas / Therapeutic advances in inborn errors of metabolism: small molecules

Resumen La mayoría de los Errores Innatos del Metabolismo (EIM) no tienen un tratamiento efectivo. Las terapias tradicionales tratan de reducir los sustratos, reemplazar el producto no formado, que puede ser esencial y suplementar con cofactores. También se emplea la activación de vías alternativas para la eliminación de productos intermedios tóxicos, como en el caso de los defectos del ciclo de la urea y para algunas condiciones, se dispone de la terapia de reemplazo enzimático (TRE), del trasplante de células hematopoyéticas y del trasplante hepático. En los últimos años se han desarrollado nuevas estrategias e caces para tratar estas enfermedades. Con esta revisión, se busca explicar de forma sencilla las distintas opciones terapéuticas más recientes, y en algunos casos, tratamientos prometedores para ciertos errores innatos de metabolismo (EIM). En concreto se hará referencia en primer lugar al uso terapéutico de pequeñas moléculas activas, que han surgido en las últimas dos décadas como un enfoque promisorio para el tratamiento de este heterogéneo grupo de trastornos, que incluyen terapia para restauración de la lectura, chaperonas farmacológicas, reguladores de la proteostasis, inhibidores de sustrato e inductores de autofagia. Estas pequeñas moléculas actúan en diferentes niveles celulares, y el conocimiento de los distintos procesos proporciona nuevas herramientas para establecer un tratamiento innovador.

Abstract Most Inborn Errors of Metabolism diseases do not have an effective treatment. Traditional therapies try to reduce substrates, replace non-formed product, which may be essential and supplement with cofactors. Activation of alternative routes for the disposal of toxic intermediates is also employed, as in the case of urea cycle defects for some conditions, enzyme replacement therapy (ERT), Hematopoietic Cell Transplantation and liver transplantation are available. In recent years new effective strategies have been developed to treat these diseases. This review seeks to explain in a simple way the different therapeutic options and, in some cases, promising treatments for certain inborn errors of metabolism (IEM). Specifically, reference will be made first to the therapeutic use of small active molecules, which have emerged in the last two decades as a promising approach for the treatment of this heterogeneous group of disorders, including: read-through therapy, pharmacological chaperones, protease inhibitors, substrate inhibitors and autophagy inducers. These small molecules act on different cellular levels, and the knowledge of the different processes provides new tools to establish an innovative treatment.

Small Molecules: Substrate Inhibitors, Chaperones, Stop-Codon Read Through, and Beyond

Abstract Lysosomal storage disorders are rare genetic disorders due to deficient lysosomal activity, which leads to progressive accumulation of nonmetabolized substrates. Patient's clinical outcomes have significantly improved since the advent of enzyme replacement therapy, even though this therapeutic approach presents important limitations, such as immune reactions, low bioavailability of recombinant enzymes, and incapability to reach the central nervous system. New strategies based on gene therapy or small molecules have been proposed and tested as an alternative to enzyme replacement therapy or to complement it. Small molecules are orally administrated, no antigenic compound that can diffuse across cell membranes and distribute in steady-state concentrations, also reaching the central nervous system. Substrate reduction therapy, pharmacological chaperones, and stop-codon read-through enhancers are small molecules currently available for the treatment of lysosomal storage disorders. This article describes the characteristics of this class of compounds and the possible strategies to improve their efficiency in future development.

Read-through Mutation in the Coat Protein ORF Suppresses Turnip Yellow Mosaic Virus Subgenomic RNA Accumulation

We have previously observed that a sequence in coat protein (CP) ORF of Turnip yellow mosaic virus (TYMV) is required for efficient replication of the virus. The sequence was predicted to take a stem-loop structure, thus termed SL2. While examining various SL2 mutants, we observed that all the modifications resulting in extension of translation beyond the CP ORF significantly suppressed subgenomic RNA accumulation. The genomic RNA level, in contrast, was not affected. Introduction of an in-frame stop codon in the CP ORF of these constructs restored the level of subgenomic RNA. Overall, the results suggest that the read-through makes the subgenomic RNA unstable.

Translational Read-Through of a Nonsense Mutation Causing Bartter Syndrome

Bartter syndrome (BS) is classified into 5 genotypes according to underlying mutant genes and BS III is caused by loss-of-function mutations in the CLCNKB gene encoding for basolateral ClC-Kb. BS III is the most common genotype in Korean patients with BS and W610X is the most common CLCNKB mutation in Korean BS III. In this study, we tested the hypothesis that the CLCNKB W610X mutation can be rescued in vitro using aminoglycoside antibiotics, which are known to induce translational read-through of a nonsense mutation. The CLCNKB cDNA was cloned into a eukaryotic expression vector and the W610X nonsense mutation was generated by site-directed mutagenesis. Cultured polarized MDCK cells were transfected with the vectors, and the read-through was induced using an aminoglycoside derivative, G418. Cellular expression of the target protein was monitored via immunohistochemistry. While cells transfected with the mutant CLCNKB failed to express ClC-Kb, G418 treatment of the cells induced the full-length protein expression, which was localized to the basolateral plasma membranes. It is demonstrated that the W610X mutation in CLCNKB can be a good candidate for trial of translational read-through induction as a therapeutic modality.