Dual reporters encoding two distinct proteins within the same mRNA have had a crucial role in identifying and characterizing unconventional mechanisms of eukaryotic translation. These mechanisms include initiation via internal ribosomal entry sites (IRESs), ribosomal frameshifting, stop codon readthrough and reinitiation. This design enables the expression of one reporter to be influenced by the specific mechanism under investigation, while the other reporter serves as an internal control. However, challenges arise when intervening test sequences are placed between these two reporters. Such sequences can inadvertently impact the expression or function of either reporter, independent of translation-related changes, potentially biasing the results. These effects may occur due to cryptic regulatory elements inducing or affecting transcription initiation, splicing, polyadenylation and antisense transcription as well as unpredictable effects of the translated test sequences on the stability and activity of the reporters. Unfortunately, these unintended effects may lead to misinterpretation of data and the publication of incorrect conclusions in the scientific literature. To address this issue and to assist the scientific community in accurately interpreting dual-reporter experiments, we have developed comprehensive guidelines. These guidelines cover experimental design, interpretation and the minimal requirements for reporting results. They are designed to aid researchers conducting these experiments as well as reviewers, editors and other investigators who seek to evaluate published data.

• MeSH
• Eukaryota * genetika   MeSH
• lidé MeSH
• messenger RNA genetika   MeSH
• proteosyntéza MeSH
• reportérové geny * MeSH
• směrnice jako téma * MeSH
• výzkumný projekt * normy   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• messenger RNA MeSH

RNAi is the sequence-specific mRNA degradation guided by siRNAs produced from long dsRNA by RNase Dicer. Proteins executing RNAi are present in mammalian cells but rather sustain the microRNA pathway. Aiming for a systematic analysis of mammalian RNAi, we report here that the main bottleneck for RNAi efficiency is the production of functional siRNAs, which integrates Dicer activity, dsRNA structure, and siRNA targeting efficiency. Unexpectedly, increased expression of Dicer cofactors TARBP2 or PACT reduces RNAi but not microRNA function. Elimination of protein kinase R, a key dsRNA sensor in the interferon response, had minimal positive effects on RNAi activity in fibroblasts. Without high Dicer activity, RNAi can still occur when the initial Dicer cleavage of the substrate yields an efficient siRNA. Efficient mammalian RNAi may use substrates with some features of microRNA precursors, merging both pathways even more than previously suggested. Although optimized endogenous Dicer substrates mimicking miRNA features could evolve for endogenous regulations, the same principles would make antiviral RNAi inefficient as viruses would adapt to avoid efficacy.

• MeSH
• buňky NIH 3T3 MeSH
• DEAD-box RNA-helikasy metabolismus   MeSH
• dvouvláknová RNA genetika   metabolismus   MeSH
• genový knockout MeSH
• kinasa eIF-2 genetika   MeSH
• malá interferující RNA metabolismus   MeSH
• mikro RNA metabolismus   MeSH
• myši MeSH
• plazmidy genetika   MeSH
• proteiny vázající RNA metabolismus   MeSH
• ribonukleasa III metabolismus   MeSH
• RNA interference fyziologie   MeSH
• sekvence nukleotidů genetika   MeSH
• transfekce MeSH
• transportní proteiny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DEAD-box RNA-helikasy MeSH
• Dicer1 protein, mouse MeSH Prohlížeč
• dvouvláknová RNA MeSH
• kinasa eIF-2 MeSH
• malá interferující RNA MeSH
• mikro RNA MeSH
• protein kinase R, mouse MeSH Prohlížeč
• proteiny vázající RNA MeSH
• Rbbp6 protein, mouse MeSH Prohlížeč
• ribonukleasa III MeSH
• trans-activation responsive RNA-binding protein MeSH Prohlížeč
• transportní proteiny MeSH

MicroRNAs (miRNAs) are small RNAs repressing gene expression. They contribute to many physiological processes and pathologies. Consequently, strategies for manipulation of the miRNA pathway are of interest as they could provide tools for experimental or therapeutic interventions. One of such tools could be small chemical compounds identified through high-throughput screening (HTS) with reporter assays. While a number of chemical compounds have been identified in such high-throughput screens, their application potential remains elusive. Here, we report our experience with cell-based HTS of a library of 12,816 chemical compounds to identify miRNA pathway modulators. We used human HeLa and mouse NIH 3T3 cell lines with stably integrated or transiently expressed luciferase reporters repressed by endogenous miR-30 and let-7 miRNAs and identified 163 putative miRNA inhibitors. We report that compounds relieving miRNA-mediated repression via stress induction are infrequent; we have found only two compounds that reproducibly induced stress granules and relieved miRNA-targeted reporter repression. However, we have found that this assay type readily yields non-specific (miRNA-independent) stimulators of luciferase reporter activity. Furthermore, our data provide partial support for previously published miRNA pathway modulators; the most notable intersections were found among anthracyclines, dopamine derivatives, flavones, and stilbenes. Altogether, our results underscore the importance of appropriate negative controls in development of small compound inhibitors of the miRNA pathway. This particularly concerns validation strategies, which would greatly profit from assays that fundamentally differ from the routinely employed miRNA-targeted reporter assays.

• Klíčová slova
• Argonaute, high-throughput screening, let-7, miR-30, miRNA,
• Publikační typ
• časopisecké články MeSH

Histone acetylation modulates alternative splicing of several hundred genes. Here, we tested the role of the histone acetyltransferase p300 in alternative splicing and showed that knockdown of p300 promotes inclusion of the fibronectin (FN1) alternative EDB exon. p300 associates with CRE sites in the promoter via the CREB transcription factor. We created mini-gene reporters driven by an artificial promoter containing CRE sites. Both deletion and mutation of the CRE site affected EDB alternative splicing in the same manner as p300 knockdown. Next we showed that p300 controls histone H4 acetylation along the FN1 gene. Consistently, p300 depletion and CRE deletion/mutation both reduced histone H4 acetylation on mini-gene reporters. Finally, we provide evidence that the effect of CRE inactivation on H4 acetylation and alternative splicing is counteracted by the inhibition of histone deacetylases. Together, these data suggest that histone acetylation could be one of the mechanisms how promoter and promoter binding proteins influence alternative splicing.

• Klíčová slova
• alternative splicing, fibronectin, histone acetylation, p300, promoter,
• MeSH
• acetylace MeSH
• alternativní sestřih * MeSH
• fibronektiny genetika   metabolismus   MeSH
• genový knockdown MeSH
• HeLa buňky MeSH
• histony metabolismus   MeSH
• integrasy genetika   MeSH
• lidé MeSH
• messenger RNA metabolismus   MeSH
• promotorové oblasti (genetika) MeSH
• protein p300 asociovaný s E1A genetika   metabolismus   MeSH
• reportérové geny MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• Cre recombinase MeSH Prohlížeč
• EP300 protein, human MeSH Prohlížeč
• fibronektiny MeSH
• FN1 protein, human MeSH Prohlížeč
• histony MeSH
• integrasy MeSH
• messenger RNA MeSH
• protein p300 asociovaný s E1A MeSH

In mammals, double-stranded RNA (dsRNA) can mediate sequence-specific RNA interference, activate sequence-independent interferon response, or undergo RNA editing by adenosine deaminases. We showed that long hairpin dsRNA expression had negligible effects on mammalian somatic cells--expressed dsRNA was slightly edited, poorly processed into siRNAs, and it did not activate the interferon response. At the same time, we noticed reduced reporter expression in transient co-transfections, which was presumably induced by expressed dsRNA. Since transient co-transfections are frequently used for studying gene function, we systematically explored the role of expressed dsRNA in this silencing phenomenon. We demonstrate that dsRNA expressed from transiently transfected plasmids strongly inhibits the expression of co-transfected reporter plasmids but not the expression of endogenous genes or reporters stably integrated in the genome. The inhibition is concentration-dependent, it is found in different cell types, and it is independent of transfection method and dsRNA sequence. The inhibition occurs at the level of translation and involves protein kinase R, which binds the expressed dsRNA. Thus, dsRNA expression represents a hidden danger in transient transfection experiments and must be taken into account during interpretation of experimental results.

• MeSH
• buňky 3T3 MeSH
• dvouvláknová RNA metabolismus   MeSH
• HEK293 buňky MeSH
• HeLa buňky MeSH
• imunoprecipitace MeSH
• lidé MeSH
• malá interferující RNA genetika   MeSH
• myši MeSH
• plazmidy genetika   MeSH
• protein-serin-threoninkinasy metabolismus   MeSH
• průtoková cytometrie MeSH
• regulace genové exprese genetika   MeSH
• reportérové geny genetika   MeSH
• transfekce metody   MeSH
• western blotting MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• dvouvláknová RNA MeSH
• malá interferující RNA MeSH
• protein-serin-threoninkinasy MeSH