Exon

About: Exon is a research topic. Over the lifetime, 38308 publications have been published within this topic receiving 1745408 citations. The topic is also known as: exons.

Nonsense-mediated mRNA decay in Drosophila: at the intersection of the yeast and mammalian pathways

Abstract: The nonsense-mediated mRNA decay (NMD) pathway promotes the rapid degradation of mRNAs containing premature stop codons (PTCs) In Caenorhabditis elegans, seven genes (smg1-7) playing an essential role in NMD have been identified Only SMG2-4 (known as UPF1-3) have orthologs in Saccharomyces cerevisiae Here we show that the Drosophila orthologs of UPF1-3, SMG1, SMG5 and SMG6 are required for the degradation of PTC-containing mRNAs, but that there is no SMG7 ortholog in this organism In contrast, orthologs of SMG5-7 are encoded by the human genome and all three are required for NMD In human cells, exon boundaries have been shown to play a critical role in defining PTCs This role is mediated by components of the exon junction complex (EJC) Contrary to expectation, however, we show that the components of the EJC are dispensable for NMD in Drosophila cells Consistently, PTC definition occurs independently of exon boundaries in Drosophila Our findings reveal that despite conservation of the NMD machinery, different mechanisms have evolved to discriminate premature from natural stop codons in metazoa

Multiple sites of alternative splicing of the rat fibronectin gene transcript.

Abstract: We describe analyses of the structure and expression of the rat fibronectin gene with particular attention to the 40-kb stretch from the center of the gene which encodes 17 type-III repeating units. Each repeat is precisely separated from its neighbors by introns and most are encoded by pairs of exons. Three repeats are encoded precisely by single exons and two of these (EIIIA and EIIIB) are alternatively spliced in a cell type-specific fashion. A third site of alternative splicing (EIIIB) reported here is similar in expression to the previously described EIIIA segment. Both are excluded from mRNA in liver cells and are, therefore, absent from plasma fibronectin. These two alternative splices, plus a third one (V) reported previously, can occur in all possible combinations giving 12 fibronectin mRNAs from a single gene. These splicing variations account for most but not all of the known fibronectin subunit variants. We report investigations designed to detect other regions of alternative splicing. We also show that the pattern of alternative splicing is somewhat altered on oncogenic transformation.

Exome Sequencing Identifies WDR35 Variants Involved in Sensenbrenner Syndrome

Abstract: Sensenbrenner syndrome/cranioectodermal dysplasia (CED) is an autosomal-recessive disease that is characterized by craniosynostosis and ectodermal and skeletal abnormalities. We sequenced the exomes of two unrelated CED patients and identified compound heterozygous mutations in WDR35 as the cause of the disease in each of the two patients independently, showing that it is possible to find the causative gene by sequencing the exome of a single sporadic patient. With RT-PCR, we demonstrate that a splice-site mutation in exon 2 of WDR35 alters splicing of RNA on the affected allele, introducing a premature stop codon. WDR35 is homologous to TULP4 (from the Tubby superfamily) and has previously been characterized as an intraflagellar transport component, confirming that Sensenbrenner syndrome is a ciliary disorder.