Exon skipping through the creation of a putative exonic splicing silencer as a consequence of the cystic fibrosis mutation R553X

Nonsense mutations that occur more than 50 bases upstream of terminal spliced junctions are generally thought to lead to degradation of the corresponding transcripts by the process of nonsense‐mediated mRNA decay. It has also been proposed that some nonsense mutations may affect splicing by the process of nonsense‐associated altered splicing (NAS), or by the disruption of a splicing regulatory element. In this study, the effect of the R553X mutation on the splicing of exon 11 of the cystic fibrosis transmembrane conductance regulator gene was investigated. Evidence that R553X causes exon 11 to skip through the creation of a putative exonic splicing silencer (ESS) was provided. The putative ESS appears to be active when located immediately upstream of a 5′ splice site. These findings argue against the possibility that R553X‐associated exon 11 skipping is caused by NAS. The study further suggests that aminoglycoside antibiotic treatment would not be effective for patients with the R553X mutation, owing to the skipping of exon 11, and further emphasises the need for detailed mechanistic characterisation of the consequences of nonsense disease mutations

Mechanism of Nonsense-Mediated mRNA Decay Stimulation by Splicing Factor SRSF1

Summary The splicing factor SRSF1 promotes nonsense-mediated mRNA decay (NMD), a quality control mechanism that degrades mRNAs with premature termination codons (PTCs). Here we show that transcript-bound SRSF1 increases the binding of NMD factor UPF1 to mRNAs while in, or associated with, the nucleus, bypassing UPF2 recruitment and promoting NMD. SRSF1 promotes NMD when positioned downstream of a PTC, which resembles the mode of action of exon junction complex (EJC) and NMD factors. Moreover, splicing and/or EJC deposition increase the effect of SRSF1 on NMD. Lastly, SRSF1 enhances NMD of PTC-containing endogenous transcripts that result from various events. Our findings reveal an alternative mechanism for UPF1 recruitment, uncovering an additional connection between splicing and NMD. SRSF1’s role in the mRNA’s journey from splicing to decay has broad implications for gene expression regulation and genetic diseases

A systematic analysis of intronic sequences downstream of 5′ splice sites reveals a widespread role for U-rich motifs and TIA1/TIAL1 proteins in alternative splicing regulation

To identify human intronic sequences associated with 5′ splice site recognition, we performed a systematic search for motifs enriched in introns downstream of both constitutive and alternative cassette exons. Significant enrichment was observed for U-rich motifs within 100 nucleotides downstream of 5′ splice sites of both classes of exons, with the highest enrichment between positions +6 and +30. Exons adjacent to U-rich intronic motifs contain lower frequencies of exonic splicing enhancers and higher frequencies of exonic splicing silencers, compared with exons not followed by U-rich intronic motifs. These findings motivated us to explore the possibility of a widespread role for U-rich motifs in promoting exon inclusion. Since cytotoxic granule-associated RNA binding protein (TIA1) and TIA1-like 1 (TIAL1; also known as TIAR) were previously shown in vitro to bind to U-rich motifs downstream of 5′ splice sites, and to facilitate 5′ splice site recognition in vitro and in vivo, we investigated whether these factors function more generally in the regulation of splicing of exons followed by U-rich intronic motifs. Simultaneous knockdown of TIA1 and TIAL1 resulted in increased skipping of 36/41 (88%) of alternatively spliced exons associated with U-rich motifs, but did not affect 32/33 (97%) alternatively spliced exons that are not associated with U-rich motifs. The increase in exon skipping correlated with the proximity of the first U-rich motif and the overall “U-richness” of the adjacent intronic region. The majority of the alternative splicing events regulated by TIA1/TIAL1 are conserved in mouse, and the corresponding genes are associated with diverse cellular functions. Based on our results, we estimate that ∼15% of alternative cassette exons are regulated by TIA1/TIAL1 via U-rich intronic elements

Antisense oligonucleotide modulation of non-productive alternative splicing upregulates gene expression

Restoration of normal gene expression is one way to treat monogenic disorders. Here the authors target naturally occurring non-productive alternative splicing using antisense oligonucleotides to promote the production of functional proteins

Antisense oligonucleotide-directed inhibition of nonsense-mediated mRNA decay

Nonsense-mediated mRNA decay (NMD) is a cellular quality-control mechanism that is thought to exacerbate the phenotype of certain pathogenic nonsense mutations by preventing the expression of semi-functional proteins. NMD also limits the efficacy of read-through compound (RTC)-based therapies. Here, we report a gene-specific method of NMD inhibition using antisense oligonucleotides (ASOs) and combine this approach with an RTC to effectively restore the expression of full-length protein from a nonsense-mutant allele

Detection of a cystic fibrosis modifier locus for meconium ileus on human chromosome 19q13 [3]

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VIII Premio Nacional de Educación para el Desarrollo “Vicente Ferrer” 2016 : buenas prácticas

La AECID junto con el Minis¬terio de Educación, Cultura y Deporte convoca anualmente los premios de educación para el desarrollo que están dirigidos a todos los centros docentes españoles sostenidos con fondos públicos que impartan educación infantil, educación primaria, educación secundaria obligatoria, bachillerato y formación profesional. Se recogen las buenas prácticas de los docentes premiados en esta edición. Docentes que en el ejercicio de su función educadora han convertido el proceso educativo en un proceso dinámico e interactivo que permite al alumnado desarrollar un conocimiento crítico de nuestro mundo. Profesores y profe-soras que han estimulado la participación del alumnado en la construcción de estructuras sociales más justas y solidarias, y han promovido actuaciones basadas en el principio de la corresponsabilidad de todos los actores implicados. El premio reconoce el esfuerzo realizado por centros educativos que establecen y creen en un modelo educativo que propone resaltar el papel de las personas y generar conciencias de carácter global que permitan al alumnado ser pieza clave de la ciudadanía del futuro, con un dinamismo que afronte las nuevas realidades desde una perspectiva más humana y responsable con el territorio en el que se ubican.ES