Project description:Purpose: Identification of genes regulating growth and fatness traits in pig. Methods: Hypothalamic transcriptome analysis through RNA-seq and differential expression analysis of divergent pigs for growth and fatness traits. Results: Characterization of the transcripts expressed in the porcine hypothalamus and identification of differentially expressed genes, some of them located within previously described QTL regions. Conclusions: Characterization of porcine hypothalamic transcriptome and identification of relevant genes and transcription factors related to the traits of interest.
Project description:Purpose: Identification of genes regulating growth and fatness traits in pig. Methods: Hypothalamic transcriptome analysis through RNA-seq and differential expression analysis of divergent pigs for growth and fatness traits. Results: Characterization of the transcripts expressed in the porcine hypothalamus and identification of differentially expressed genes, some of them located within previously described QTL regions. Conclusions: Characterization of porcine hypothalamic transcriptome and identification of relevant genes and transcription factors related to the traits of interest. Transcriptome sequencing of 10 hypothamic samples of two groups of divergent pigs for growth and fatness (five per group).
Project description:Leukocyte common antigen-related receptor protein tyrosine phosphatases (LAR-RPTPs) are evolutionarily conserved presynaptic cell-adhesion molecules that orchestrate multifarious synaptic adhesion pathways. Extensive alternative splicing of LAR-RPTP mRNAs, similar to neurexins, may produce innumerable LAR-RPTP isoforms that act as regulatory codes for determining the identify and strength of specific synapse signaling. However, no direct evidence for the hypothesis exists, apart from the role of LAR-RPTP splice variants in specifying region-specific, cell type-specific and neural circuit-specific properties in vivo. Here, using deep RNA sequencing (RNA-seq), we targeted Ptprs, Ptprd, and Ptprf mRNAs in diverse cell types across adult mouse brain areas. In addition to identifying novel alternatively spliced exons of Ptprd, we found pronounced cell-type-specific patterns of two microexons, meA and meB, in brain Ptprd mRNAs. Quantitative targeted proteomics uncovered profiles of LAR-RPTP proteoforms containing or lacking meA that are in line with RNA-seq results. Moreover, diverse neural circuits targeting the same neuronal popluations were dictated by the expression of different Ptprd variants characterized by distinct inclusion patterns of meA and/or meB. Remarkably, fear-related learning induced upregulation of Ptprd meA+ variants in hippocampal memory-activated dentate gyrus neurons. Furthermore, conditional ablation of Ptprd meA+ variants at presynaptic loci of distinct hippocampal circuits resulted in impairment of distinct modes of synaptic transmission and different cognitive tasks. Our data provide the first evidence of cell-type- and/or circuit-specific expression patterns and physiological functions of LAR-RPTP microexons that are dynamically regulated and likely to dictate diverse synaptic properties. In particular, we propose Ptprd splicing as a key mechanism that mediates activity-dependent neural circuit specification
Project description:Humans co-existed and interbred with other hominins which later became extinct. These archaic hominins are known to us only through fossil records and for two cases, genome sequences. Here we engineer Neanderthal and Denisovan sequences into thousands of artificial genes to reconstruct the pre-mRNA processing patterns of these extinct populations. Of the 5,224 alleles tested in this massively parallel splicing reporter assay (MaPSy), we report 969 exonic splicing mutations (ESMs) that correspond to differences in exon recognition between extant and extinct hominins. Using MaPSy splicing variants, predicted splicing variants, and splicing quantitative trait loci, we show that splice-disrupting variants experienced greater purifying selection in anatomically modern humans than in Neanderthals. Adaptively introgressed variants were enriched for moderate effect splicing variants, consistent with positive selection for alternative spliced alleles following introgression. As particularly compelling examples, we characterized a novel tissue-specific alternative splicing variant at the adaptively introgressed innate immunity gene TLR1, as well as a novel Neanderthal introgressed alternative splicing variant in the gene HSPG2 that encodes perlecan. We further identified potentially pathogenic splicing variants found only in Neanderthals and Denisovans in genes related to sperm maturation and immunity. Finally, we found splicing variants that may contribute to variation among modern humans in total bilirubin, balding, hemoglobin levels, and lung capacity. Our findings provide novel insights into natural selection acting on splicing in human evolution and demonstrate how functional assays can be used to identify candidate causal variants underlying differences in gene regulation and phenotype.
Project description:It is estimated that 10-30% of disease-associated genetic variants affect splicing. Splicing variants may generate deleteriously altered gene product and are potential therapeutic targets. However, experimental diagnosis for splicing variants is time-consuming and reliable computational prediction tools have not been established, especially for the 3’ end of introns. The major challenge lies in the redundant and ill-defined branch site motif therein. Here, we carried out unbiased massively parallel splicing assays on 5,307 disease-associated variants overlapped with branch sites. We observed that 11.0% (455 out of 4,154 valid comparisons) of candidate variants showed a consistent pattern of altered splicing across four experimental replicates, among which 244 candidates (6.1%) presented more than two-fold changes in the use of noncanonical splice sites and these are named high-confidence (HC) significant candidates.
Project description:Using a high throughput splicing reporter assay, we tested 1,080 single nucleotide variants in POU1F1, a key transcription factor essential for pituitary development. Our saturation splicing effect map identifies 96 splice disruptive variants, including 14 synonymous variants, of which 8 were found in unrelated patients diagnosed with hypopituitarism.
Project description:Background: Substantial progress has been made in the identification of sequence elements that control mRNA splicing and the genetic variants in these elements that alter mRNA splicing (referred to as splicing quantitative trait loci -- sQTLs). Genetic variants that affect mRNA splicing in trans are harder to identify because their effects can be more subtle and diffuse, and the variants are not co-located with their targets. We carried out a transcriptome-wide analysis of the effects of a mutation in a ubiquitous splicing factor that causes retinitis pigmentosa (RP) on mRNA splicing, using exon microarrays. Results: Exon microarray data was generated from whole blood samples obtained from four individuals with a mutation in the splicing factor PRPF8 and four sibling controls. Although the mutation has no known phenotype in blood, there was evidence of widespread differences in splicing between cases and controls (affecting between 10\% and 25\% of exons). Most probesets with significantly different inclusion (defined as the expression intensity of the exon divided by the expression of the corresponding transcript) between cases and controls had higher inclusion in cases and corresponded to exons that were shorter than average, AT-rich, located towards the 5' end of the gene and flanked by long introns. Introns flanking affected probesets were particularly depleted for the shortest category of introns, associated with splicing via intron definition. Conclusions: Our results show that a mutation in a splicing factor, with a phenotype that is restricted to retinal tissue, acts as a trans-sQTL cluster in whole blood samples. Characteristics of the affected exons suggest that they are spliced co-transcriptionally and via exon definition. Eight samples consisting of four sibling pairs were analysed. One individual in each pair harboured an RP-causing mutation on the PRPF8 gene (cases). Unaffected siblings were used as controls.
Project description:Most clinical diagnostic settings and genomic research focus almost exclusively on coding regions and essential splice sites, mostly ignoring non-coding variants. Indeed, the investigation of intronic mis-splicing variants interpreting mechanisms to disease-associated splicing events requires both genomic and transcriptomic data. Unfortunately, there are not many datasets where both are available, leading to the understanding of intronic variants in diseases full of gaps. In this study, we present for the first time a full-length single nuclei RNA-sequencing (snRNA-Seq) approach improving the proper investigation of pathogenic mis-splicing intronic variants in pancreatic cancer showing its contribution to abnormal splicing changes and their transcriptional effects. Finally, we discuss the demands of further machine learning-based methods to process the growing number of single cell data and to enhance the precision and recall.