Project description:Transcription and pre-mRNA alternative splicing are highly regulated processes that play major roles in modulating eukaryotic gene expression. It is increasingly apparent that other pathways of RNA metabolism, including small RNA biogenesis, can regulate these processes. However, a direct link between alternative pre- mRNA splicing and small RNA pathways has remained elusive. Here we show that the small RNA pathway protein Argonaute-2 (Ago-2) regulates alternative pre-mRNA splicing patterns of specific transcripts in the Drosophila nucleus using genome-wide methods in conjunction with RNAi in cell culture and Ago-2 deletion or catalytic site mutations in Drosophila adults. Moreover, we show that nuclear Argonaute-2 binds to specific chromatin sites near gene promoters and negatively regulates the transcription of the Ago-2-associated target genes. These transcriptional target genes are also bound by Polycomb group (PcG) transcriptional repressor proteins and change during development, implying that Ago-2 may regulate Drosophila development. Impor- tantly, both of these activities were independent of the catalytic activity of Ago-2, suggesting new roles for Ago-2 in the nucleus. Finally, we determined the nuclear RNA-binding profile of Ago-2, found it bound to several splicing target transcripts, and identified a G-rich RNA-binding site for Ago-2 that was enriched in these transcripts. These results suggest two new nuclear roles for Ago-2: one in pre-mRNA splicing and one in transcriptional repression. Input chromatin, 2 replicates of Ago2 ChIP-seq
Project description:RNA binding proteins play an important role in regulating alternative pre-mRNA splicing and in turn cellular gene expression. Polypyrimidine tract binding proteins, PTBP1 and PTBP2, are paralogous RNA binding proteins that play a critical role in the process of neuronal differentiation and maturation; changes in the concentration of PTBP proteins during neuronal development direct splicing changes in many transcripts that code for proteins critical for neuronal differentiation. How the two related proteins regulate different sets of neuronal exons is unclear. The distinct splicing activities of PTBP1 and PTBP2 can be recapitulated in an in vitro splicing system with the differentially regulated N1 exon of the c-src pre-mRNA. Here, we conducted experiments under these in vitro splicing conditions to identify PTBP1 and PTBP2 interacting partner proteins.
Project description:We tested whether the defects in spermatogenesis and increases in germ cell apoptosis that are induced by under-nutrition are associated with changes in mRNA expression and pre-mRNA alternative splicing in the testis. Groups of 8 male sheep were fed for a 10% increase or 10% decrease in body mass over 65 days. We identified 2,243 mRNAs, including TP53 and Claudin 11, that were differentially expressed in testis from underfed and well-fed sheep (FDR < 0.1), and found that their changes in expression were associated with germ cells, testis size, cell cycle and spermatogenesis variations. Furthermore, pairs of 269 mRNAs and 48 miRNAs were indentified based on target prediction and the negative regulatory effect of miRNAs on mRNA expression with functions involved in abnormal reproductive morphology, apoptosis and male infertility. Nutrition did not affect the total number of alternative splicing junctions, but affected 1,040 alternative splicing events (FDR < 0.05, ∆PSI > 10%). A total of 788 genes, including CREM, MAP2, HIPK3 and TRa2β, were differentially spliced between dietary treatments, with functions related to protein localization, cellular metabolic process, post-translational protein modification and spermatogenesis. In addition, three gene modules were positively correlated with spermatogenesis-related phenotypic traits and negatively related to apoptosis-related phenotypic traits. Among these gene modules, seven (CFLAR, PTPRC, F2R, MAP3K1, EPHA7, APP, BCAP31) were also differentially expressed between nutritional treatments, indicating their potential as markers of spermatogenesis or apoptosis. We conclude that under-nutrition causes changes in mRNAs and pre-mRNA alternative splicing that, at least partly, contribute to disrupted spermatogenesis and increased germ cell apoptosis.
Project description:Transcription and pre-mRNA alternative splicing are highly regulated processes that play major roles in modulating eukaryotic gene expression. It is increasingly apparent that other pathways of RNA metabolism, including small RNA biogenesis, can regulate these processes. However, a direct link between alternative pre- mRNA splicing and small RNA pathways has remained elusive. Here we show that the small RNA pathway protein Argonaute-2 (Ago-2) regulates alternative pre-mRNA splicing patterns of specific transcripts in the Drosophila nucleus using genome-wide methods in conjunction with RNAi in cell culture and Ago-2 deletion or catalytic site mutations in Drosophila adults. Moreover, we show that nuclear Argonaute-2 binds to specific chromatin sites near gene promoters and negatively regulates the transcription of the Ago-2-associated target genes. These transcriptional target genes are also bound by Polycomb group (PcG) transcriptional repressor proteins and change during development, implying that Ago-2 may regulate Drosophila development. Impor- tantly, both of these activities were independent of the catalytic activity of Ago-2, suggesting new roles for Ago-2 in the nucleus. Finally, we determined the nuclear RNA-binding profile of Ago-2, found it bound to several splicing target transcripts, and identified a G-rich RNA-binding site for Ago-2 that was enriched in these transcripts. These results suggest two new nuclear roles for Ago-2: one in pre-mRNA splicing and one in transcriptional repression.
Project description:Dysregulation of pre-mRNA alternative splicing (AS) is closely associated with cancers. However, the relationships between the AS and classic oncogenes/tumor suppressors are largely unknown. Here we show that the deletion of tumor suppressor PTEN alters pre-mRNA splicing in its phosphatase-independent manner, and identify262 PTEN-regulated AS events in 293T cells by RNA sequencing, which are associated with significant worse outcome of cancer patients. Based on these findings, we report that nuclear PTEN interacts with the splicing machinery, spliceosome, to regulate its assembly and pre-mRNA splicing. Especially, the exon-2b exclusion of GOLGA2 contributes to PTEN knockdown-induced tumorigenesis by promoting dramatic Golgi extension and secretion, and PTEN depletion significantly sensitizes cancer cells to secretion inhibitors, Brefeldin A and Golgicide A. Given that many cancers lack PTEN expression, our results suggest that Golgi secretion inhibitors alone or in combination with PI3K/Akt kinase inhibitors may be therapeutically useful for PTEN-deficient cancers.
Project description:Transcription and pre-mRNA alternative splicing are highly regulated processes that play major roles in modulating eukaryotic gene expression. It is increasingly apparent that other pathways of RNA metabolism, including small RNA biogenesis, can regulate these processes. However, a direct link between alternative pre- mRNA splicing and small RNA pathways has remained elusive. Here we show that the small RNA pathway protein Argonaute-2 (Ago-2) regulates alternative pre-mRNA splicing patterns of specific transcripts in the Drosophila nucleus using genome-wide methods in conjunction with RNAi in cell culture and Ago-2 deletion or catalytic site mutations in Drosophila adults. Moreover, we show that nuclear Argonaute-2 binds to specific chromatin sites near gene promoters and negatively regulates the transcription of the Ago-2-associated target genes. These transcriptional target genes are also bound by Polycomb group (PcG) transcriptional repressor proteins and change during development, implying that Ago-2 may regulate Drosophila development. Impor- tantly, both of these activities were independent of the catalytic activity of Ago-2, suggesting new roles for Ago-2 in the nucleus. Finally, we determined the nuclear RNA-binding profile of Ago-2, found it bound to several splicing target transcripts, and identified a G-rich RNA-binding site for Ago-2 that was enriched in these transcripts. These results suggest two new nuclear roles for Ago-2: one in pre-mRNA splicing and one in transcriptional repression. 2 Ago2 mutants, 51B and V966M, heterozygotes and homozygotes of both each sequenced in duplicate
Project description:The DEAD-box (DDX) proteins function in diverse cellular processes including RNA alternative splicing, and are linked to immune-mediated diseases. However, little is known about the roles of DDXs in skin inflammatory diseases. Here, we show that DDX5, one of the founding members of the DDX RNA helicase family, controls skin inflammation and participates in the pathogenesis of psoriasis via regulating IL-36R pre-mRNA splicing. We found that both mRNA and protein of DDX5 are decreased in lesional skin from patients with psoriasis and psoriasis-like mice, and that mice with keratinocyte-specific ablation of DDX5 spontaneously develop psoriasis-like phenotypes. Mechanistically, DDX5 complexes with serine/arginine-rich splicing factor 1(SRSF1) to typically regulate IL-36R pre-mRNA splicing in keratinocytes, which generates mRNAs encoding full-length IL-36R and a previously unknown soluble form of IL-36R (sIL-36R). sIL-36R controls IL-36/IL-36R signaling by competing with IL-36R for IL-36γ ligation. The reduction or deficiency of DDX5 leads to IL-36R pre-mRNA splicing preferring to the generation of IL-36R but not sIL-36R, thereby selectively amplifying inflammatory responses of keratinocytes to IL-36γ and then aggravating cutaneous inflammation in psoriasis. Genetic restoration or intradermal administration of sIL-36R in psoriasis-like mice suppresses IL-36R signaling and alleviates the disease phenotype of psoriasis. Altogether, these data reveal a pathogenic role of DDX5 during psoriasis, and provide mechanistic insights into the regulation of IL-36R splicing and its impact on psoriasis development.
Project description:Transcription and pre-mRNA alternative splicing are highly regulated processes that play major roles in modulating eukaryotic gene expression. It is increasingly apparent that other pathways of RNA metabolism, including small RNA biogenesis, can regulate these processes. However, a direct link between alternative pre- mRNA splicing and small RNA pathways has remained elusive. Here we show that the small RNA pathway protein Argonaute-2 (Ago-2) regulates alternative pre-mRNA splicing patterns of specific transcripts in the Drosophila nucleus using genome-wide methods in conjunction with RNAi in cell culture and Ago-2 deletion or catalytic site mutations in Drosophila adults. Moreover, we show that nuclear Argonaute-2 binds to specific chromatin sites near gene promoters and negatively regulates the transcription of the Ago-2-associated target genes. These transcriptional target genes are also bound by Polycomb group (PcG) transcriptional repressor proteins and change during development, implying that Ago-2 may regulate Drosophila development. Impor- tantly, both of these activities were independent of the catalytic activity of Ago-2, suggesting new roles for Ago-2 in the nucleus. Finally, we determined the nuclear RNA-binding profile of Ago-2, found it bound to several splicing target transcripts, and identified a G-rich RNA-binding site for Ago-2 that was enriched in these transcripts. These results suggest two new nuclear roles for Ago-2: one in pre-mRNA splicing and one in transcriptional repression.
Project description:Since m6A demethylases (FTO and ALKBH5) have been reported to be involved in pre-mRNA splicing regulation, we hypothesized that dynamic m6A distribution during mRNA maturation might involve removal of m6A in internal exons by FTO or ALKBH5 accompanied by splicing factors. To explore this we performed pull-down assays coupled with protein mass spectrometry.