The steroid hormone ecdysone coordinates insect growth and development, directing the major postembryonic transition of forms, metamorphosis. The steroid-deficient ecdysoneless1 (ecd1) strain of Drosophila melanogaster has long served to assess the impact of ecdysone on gene regulation, morphogenesis, or reproduction. However, ecd also exerts cell-autonomous effects independently of the hormone, and mammalian Ecd homologs have been implicated in cell cycle regulation and cancer. Why the Drosophila ecd1 mutants lack ecdysone has not been resolved. Here, we show that in Drosophila cells, Ecd directly interacts with core components of the U5 snRNP spliceosomal complex, including the conserved Prp8 protein. In accord with a function in pre-mRNA splicing, Ecd and Prp8 are cell-autonomously required for survival of proliferating cells within the larval imaginal discs. In the steroidogenic prothoracic gland, loss of Ecd or Prp8 prevents splicing of a large intron from CYP307A2/spookier (spok) pre-mRNA, thus eliminating this essential ecdysone-biosynthetic enzyme and blocking the entry to metamorphosis. Human Ecd (hEcd) can substitute for its missing fly ortholog. When expressed in the Ecd-deficient prothoracic gland, hEcd re-establishes spok pre-mRNA splicing and protein expression, restoring ecdysone synthesis and normal development. Our work identifies Ecd as a novel pre-mRNA splicing factor whose function has been conserved in its human counterpart. Whether the role of mammalian Ecd in cancer involves pre-mRNA splicing remains to be discovered.
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http://dx.doi.org/10.1371/journal.pgen.1004287 | DOI Listing |
Mol Cell
January 2025
Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, Irvine, CA 92697, USA. Electronic address:
Pre-mRNA 3' processing is an integral step in mRNA biogenesis. However, where this process occurs in the nucleus remains unknown. Here, we demonstrate that nuclear speckles (NSs), membraneless organelles enriched with splicing factors, are major sites for pre-mRNA 3' processing in human cells.
View Article and Find Full Text PDFRNA
December 2024
Instiute of Bioorganic Chemistry PAS
In this article, we present an approach to maximizing the splicing regulatory properties of splice-switching oligonucleotide (SSO) designed to regulate alternative splicing of PKM pre-mRNA. The studied SSO interacts with the regulatory element in exon 10 of PKM pre-mRNA and contributes to a significant reduction of PKM2 level with a simultaneous increase of the PKM1 isoform. This SSO forms a duplex not only with the regulatory fragment of exon 10 but also with a similar RNA fragment of intron 9.
View Article and Find Full Text PDFPlants (Basel)
December 2024
A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia.
Among the long non-coding RNAs that are currently recognized as important regulatory molecules influencing a plethora of processes in eukaryotic cells, circular RNAs (circRNAs) represent a distinct class of RNAs that are predominantly produced by back-splicing of pre-mRNA. The most studied regulatory mechanisms involving circRNAs are acting as miRNA sponges, forming R-loops with genomic DNA, and encoding functional proteins. In addition to circRNAs generated by back-splicing, two types of circRNAs capable of autonomous RNA-RNA replication and systemic transport have been described in plants: viroids, which are infectious RNAs that cause a number of plant diseases, and retrozymes, which are transcripts of retrotransposon genomic loci that are capable of circularization due to ribozymes.
View Article and Find Full Text PDFZhong Nan Da Xue Xue Bao Yi Xue Ban
July 2024
Southern Hospital affiliated with Shenzhen University, Shenzhen Guangdong 518001, China.
Triple-negative breast cancer (TNBC) is a highly aggressive breast cancer subtype with poor prognosis. RNA alternative splicing dysregulation plays a critical role in the initiation and progression of TNBC. This article systematically introduces the basic process of RNA splicing and then focuses on reviewing the aberrant alternative splicing events and their biological effects in TNBC: 1) Multiple splicing-related factors promote tumor cell proliferation and mediate chemotherapy resistance by regulating the alternative splicing of genes involved in cell survival and drug response; 2) dysregulation of splicing regulatory networks leads to altered splicing of multiple metastasis-related genes, promoting tumor invasion and metastasis; 3) aberrant alternative splicing events participate in tumor progression by affecting the expression of DNA damage repair genes; 4) dysregulation of alternative splicing is also involved in the regulation of tumor immune evasion and stem cell properties.
View Article and Find Full Text PDFHighly recurrent somatic mutations in the gene encoding the core splicing factor SF3B1 are drivers of multiple cancer types. SF3B1 is a scaffold protein that orchestrates multivalent protein-protein interactions within the spliceosome that are essential for recognizing the branchsite (BS) and selecting the 3' splice site during the earliest stage of pre-mRNA splicing. In this review, we first describe the molecular mechanism by which multiple oncogenic SF3B1 mutations disrupt splicing.
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