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The spliceosome deposits multiple proteins 20-24 nucleotides upstream of mRNA exon-exon junctions.

ABSTRACT: Eukaryotic mRNAs exist in vivo as ribonucleoprotein particles (mRNPs). The protein components of mRNPs have important functions in mRNA metabolism, including effects on subcellular localization, translational efficiency and mRNA half-life. There is accumulating evidence that pre-mRNA splicing can alter mRNP structure and thereby affect downstream mRNA metabolism. Here, we report that the spliceosome stably deposits several proteins on mRNAs, probably as a single complex of approximately 335 kDa. This complex protects 8 nucleotides of mRNA from complete RNase digestion at a conserved position 20-24 nucleotides upstream of exon-exon junctions. Splicing-dependent RNase protection of this region was observed in both HeLa cell nuclear extracts and Xenopus laevis oocyte nuclei. Immunoprecipitations revealed that five components of the complex are the splicing-associated factors SRm160, DEK and RNPS1, the mRNA-associated shuttling protein Y14 and the mRNA export factor REF. Possible functions for this complex in nucleocytoplasmic transport of spliced mRNA, as well as the nonsense-mediated mRNA decay pathway, are discussed.

SUBMITTER: Le Hir H

PROVIDER: S-EPMC305905 | biostudies-literature | 2000 Dec

REPOSITORIES: biostudies-literature

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The spliceosome deposits multiple proteins 20-24 nucleotides upstream of mRNA exon-exon junctions.

Le Hir H H Izaurralde E E Maquat L E LE Moore M J MJ

The EMBO journal 20001201 24

Eukaryotic mRNAs exist in vivo as ribonucleoprotein particles (mRNPs). The protein components of mRNPs have important functions in mRNA metabolism, including effects on subcellular localization, translational efficiency and mRNA half-life. There is accumulating evidence that pre-mRNA splicing can alter mRNP structure and thereby affect downstream mRNA metabolism. Here, we report that the spliceosome stably deposits several proteins on mRNAs, probably as a single complex of approximately 335 kDa. ...[more]

PMID: 11118221

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Project description:EGFR exon 20 insertions (EGFR e20ins) account for up to 10% of EGFR mutations in lung cancer; however, tumors with EGFR e20ins had poor response rates to EGFR tyrosine kinase inhibitors (TKIs) including gefitinib, erlotinib, afatinib, and osimertinib, and the heterogeneity of EGFR e20ins further complicates the clinical studies. Here, we retrospectively screened next-generation sequencing (NGS) data from 24 468 lung cancer patients, and a total of 85 unique EGFR e20ins variants were identified in 547 cases (2.24%), with p.A767_V769dup (25.1%) and p.S768_D770dup (17.6%) being the most prevalent ones. Comprehensive genomic profiling revealed that TP53 mutations frequently coexisted with p.H773dup (77.8%, P = 0.0558) and p.A767_V769dup (62.8%, P = 0.0325), while RB1 mutations usually co-occurred with p.H773_V774insAH (33.3%, P = 0.0551), implying that different EGFR e20ins variants might require distinct genomic context for tumorigenesis and/or maintenance. Despite that treatment regimens were highly diverse for EGFR e20ins-positive patients, we observed an overall response rate of 14% and a disease control rate (DCR) of 38.4% in 65 patients who received at least one EGFR TKI. The progression-free survival (PFS) differs significantly in six representative EGFR e20ins variants (P = 0.017), and EGFR p.A763_Y764insFQEA was associated with better PFS than other EGFR e20ins when treating with various EGFR TKIs. Some EGFR e20ins variants showed at least partial response to first-generation EGFR TKIs, including p.A767_V769dup, p.S768_D770dup, p.N771_H773dup, p.A763_Y764insFQEA, and p.D770_N771insG. Poziotinib achieved higher DCR for p.S768_D770dup than for p.A767_V769dup, whereas osimertinib showed limited effects for these two insertions when used as the first-line treatment. Overall, our results demonstrated that EGFR e20ins were highly diversified in terms of insertion patterns and co-occurring mutations and these EGFR e20ins variants showed different clinical responses to various EGFR TKIs, suggesting the clinical importance of selecting proper EGFR TKI treatment based on the specific EGFR e20ins type.

Dataset Information

The spliceosome deposits multiple proteins 20-24 nucleotides upstream of mRNA exon-exon junctions.

Publications

The spliceosome deposits multiple proteins 20-24 nucleotides upstream of mRNA exon-exon junctions.

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