Over 40% of male and ~16% of female carriers of a premutation FMR1 allele (55-200 CGG repeats) will develop fragile X-associated tremor/ataxia syndrome, an adult onset neurodegenerative disorder, while about 20% of female carriers will develop fragile X-associated primary ovarian insufficiency. Marked elevation in FMR1 mRNA transcript levels has been observed with premutation alleles, and RNA toxicity due to increased mRNA levels is the leading molecular mechanism proposed for these disorders. However, although the FMR1 gene undergoes alternative splicing, it is unknown whether all or only some of the isoforms are overexpressed in premutation carriers and which isoforms may contribute to…
In this study we identified two 3′-coterminal RNA molecules in the pseudorabies virus. The highly abundant short transcript (CTO-S) proved to be encoded between the ul21 and ul22 genes in close vicinity of the replication origin (OriL) of the virus. The less abundant long RNA molecule (CTO-L) is a transcriptional readthrough product of the ul21 gene and overlaps OriL. These polyadenylated RNAs were characterized by ascertaining their nucleotide sequences with the Illumina HiScanSQ and Pacific Biosciences Real-Time (PacBio RSII) sequencing platforms and by analyzing their transcription kinetics through use of multi-time-point Real-Time RT-PCR and the PacBio RSII system. It emerged…
Although transcriptional and posttranscriptional events are detected in RNA-Seq data from second-generation sequencing, full-length mRNA isoforms are not captured. On the other hand, third-generation sequencing, which yields much longer reads, has current limitations of lower raw accuracy and throughput. Here, we combine second-generation sequencing and third-generation sequencing with a custom-designed method for isoform identification and quantification to generate a high-confidence isoform dataset for human embryonic stem cells (hESCs). We report 8,084 RefSeq-annotated isoforms detected as full-length and an additional 5,459 isoforms predicted through statistical inference. Over one-third of these are novel isoforms, including 273 RNAs from gene loci that have…
FMR1 premutation carriers (55-200 CGG repeats) are at risk for developing Fragile X-associated Tremor/Ataxia Syndrome (FXTAS), an adult onset neurodegenerative disorder. Approximately 20% of female carriers will develop Fragile X-associated Primary Ovarian Insufficiency (FXPOI), in addition to a number of clinical problems affecting premutation carriers throughout their life span. Marked elevation in FMR1 mRNA levels have been observed with premutation alleles resulting in RNA toxicity, the leading molecular mechanism proposed for the FMR1 associated disorders observed in premutation carriers. The FMR1 gene undergoes alternative splicing and we have recently reported that the relative abundance of all FMR1 mRNA isoforms is…
The hypervariable Dscam1 (Down syndrome cell adhesion molecule 1) gene can produce thousands of different ectodomain isoforms via mutually exclusive alternative splicing. Dscam1 appears to be involved in the immune response of some insects and crustaceans. It has been proposed that the diverse isoforms may be involved in the recognition of, or the defence against, diverse parasite epitopes, although evidence to support this is sparse. A prediction that can be generated from this hypothesis is that the gene expression of specific exons and/or isoforms is influenced by exposure to an immune elicitor. To test this hypothesis, we for the first…
Complex biological systems rely on cell surface cues that govern cellular self-recognition and selective interactions with appropriate partners. Molecular diversification of cell surface recognition molecules through DNA recombination and complex alternative splicing has emerged as an important principle for encoding such interactions. However, the lack of tools to specifically detect and quantify receptor protein isoforms is a major impediment to functional studies. We here developed a workflow for targeted mass spectrometry by selected reaction monitoring (SRM) that permits quantitative assessment of highly diversified protein families. We apply this workflow to dissecting the molecular diversity of the neuronal neurexin receptors and…