Spliceosome factors target timeless ( tim ) mRNA to control clock protein accumulation and circadian behavior in Drosophila

• Published in: eLife 2018-12, Vol.7
• Main Authors: Shakhmantsir, Iryna, Nayak, Soumyashant, Grant, Gregory R, Sehgal, Amita
• Format: Article
• Language: English
• Subjects: Alternative splicing; Animals; Behavior; Circadian Clocks - genetics; Circadian rhythm; Circadian Rhythm - genetics; Circadian rhythms; Clock gene; CLOCK Proteins - genetics; CLOCK Proteins - metabolism; Drosophila; Drosophila melanogaster - genetics; Drosophila melanogaster - metabolism; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; Exons; Feedback; feedback loop; Feedback, Physiological; Gene expression; Genetics and Genomics; Insects; Introns; Kinases; Light; Medicine; Mitochondrial DNA; molecular clock; mRNA processing; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Period Circadian Proteins - genetics; Period Circadian Proteins - metabolism; Post-transcription; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Proteins; Research Communication; Ribonucleoproteins (small nuclear); Ribonucleoproteins, Small Nuclear - genetics; Ribonucleoproteins, Small Nuclear - metabolism; RNA Splicing; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA-mediated interference; Sequence Analysis, RNA; Signal Transduction; Spliceosomes - genetics; Spliceosomes - metabolism; splicing; timeless; Timeless protein
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.39821

Transcription-translation feedback loops that comprise eukaryotic circadian clocks rely upon temporal delays that separate the phase of active transcription of clock genes, such as Drosophila and from negative feedback by the two proteins. However, our understanding of the mechanisms involved is incomplete. Through an RNA interference screen, we found that pre-mRNA processing 4 (PRP4) kinase, a component of the U4/U5.U6 triple small nuclear ribonucleoprotein (tri-snRNP) spliceosome, and other tri-snRNP components regulate cycling of the molecular clock as well as rest:activity rhythms. Unbiased RNA-Sequencing uncovered an alternatively spliced intron in whose increased retention upon downregulation leads to decreased TIM levels. We demonstrate that the splicing of is rhythmic with a phase that parallels delayed accumulation of the protein in a 24 hr cycle. We propose that alternative splicing constitutes an important clock mechanism for delaying the daily accumulation of clock proteins, and thereby negative feedback by them. This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).