Minor introns are embedded molecular switches regulated by highly unstable U6atac snRNA.

Abstract

Eukaryotes have two types of spliceosomes, comprised of either major (U1, U2, U4, U5, U6) or minor (U11, U12, U4atac, U6atac; <1%) snRNPs. The high conservation of minor introns, typically one amidst many major introns in several hundred genes, despite their poor splicing, has been a long-standing enigma. Here, we discovered that the low abundance minor spliceosome's catalytic snRNP, U6atac, is strikingly unstable (t½<2 hr). We show that U6atac level depends on both RNA polymerases II and III and can be rapidly increased by cell stress-activated kinase p38MAPK, which stabilizes it, enhancing mRNA expression of hundreds of minor intron-containing genes that are otherwise suppressed by limiting U6atac. Furthermore, p38MAPK-dependent U6atac modulation can control minor intron-containing tumor suppressor PTEN expression and cytokine production. We propose that minor introns are embedded molecular switches regulated by U6atac abundance, providing a novel post-transcriptional gene expression mechanism and a rationale for the minor spliceosome's evolutionary conservation. DOI:http://dx.doi.org/10.7554/eLife.00780.001.

• Authors: Ihab Younis, Kimberly Dittmar, Wei Wang, Shawn W Foley, Michael G Berg, Karen Y Hu, Zhi Wei, Lili Wan, Gideon Dreyfuss
• Journal: eLife (Elife) Vol. 2 Pg. e00780 (Jul 30 2013) ISSN: 2050-084X [Print] England
• PMID: 23908766 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• DNA Primers
• RNA, Small Nuclear
• p38 Mitogen-Activated Protein Kinases

Topics

• Base Sequence
• DNA Primers
• Enzyme Activation
• Gene Expression Regulation
• Introns
• Oxidative Stress
• RNA Splicing
• RNA, Small Nuclear (physiology)
• Real-Time Polymerase Chain Reaction
• Up-Regulation
• p38 Mitogen-Activated Protein Kinases (metabolism)