Biomaterial Database

Inverse splicing of a discontinuous pre-mRNA intron generates a circular exon in a HeLa cell nuclear extract. 1996

S Braun, and H Domdey, and K Wiebauer

Institut für Biochemie, Genzentrum der Ludwig-Maximillians-Universität München, Germany.

We have recently reported the first example of inverse splicing of a eukaryotic pre-mRNA intron using a whole cell extract from the yeast Saccharomyces cerevisiae. The concomitant circularization of the exon in the course of this splicing reaction gave rise to the hypothesis that the circular RNA species, which had been recently discovered in vivo in mammalian cells, were generated by inverse splicing. Here we report the formation of a circular exon in HeLa cell nuclear extracts by an inverse splicing reaction of the second intron of the human beta-globin gene from a pre-mRNA transcript in which the two intron halves flanked an artificially fused, single exon. Our data demonstrate that the mammalian pre-mRNA splicing system has indeed an intrinsic capability of aligning splice sites in reverse order and that this alignment can be followed by a complete splicing reaction, whereby the discontinuous intron sequences are removed. Thus we propose that circular exons in vivo arise as a result of an inverse splicing reaction following the pairing of a 5' splice site with an upstream 3' splice site and that the frequency of this event is influenced by the presence and strength of other, competing splice sites.

UI	MeSH Term	Description	Entries
D007438	Introns	Sequences of DNA in the genes that are located between the EXONS. They are transcribed along with the exons but are removed from the primary gene transcript by RNA SPLICING to leave mature RNA. Some introns code for separate genes.	Intervening Sequences,Sequences, Intervening,Intervening Sequence,Intron,Sequence, Intervening
D009690	Nucleic Acid Conformation	The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.	DNA Conformation,RNA Conformation,Conformation, DNA,Conformation, Nucleic Acid,Conformation, RNA,Conformations, DNA,Conformations, Nucleic Acid,Conformations, RNA,DNA Conformations,Nucleic Acid Conformations,RNA Conformations
D002457	Cell Extracts	Preparations of cell constituents or subcellular materials, isolates, or substances.	Cell Extract,Extract, Cell,Extracts, Cell
D002467	Cell Nucleus	Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)	Cell Nuclei,Nuclei, Cell,Nucleus, Cell
D005091	Exons	The parts of a transcript of a split GENE remaining after the INTRONS are removed. They are spliced together to become a MESSENGER RNA or other functional RNA.	Mini-Exon,Exon,Mini Exon,Mini-Exons
D005914	Globins	A superfamily of proteins containing the globin fold which is composed of 6-8 alpha helices arranged in a characterstic HEME enclosing structure.	Globin
D006367	HeLa Cells	The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for, among other things, VIRUS CULTIVATION and PRECLINICAL DRUG EVALUATION assays.	Cell, HeLa,Cells, HeLa,HeLa Cell
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000079962	RNA, Circular	RNA molecules in which the 3' and 5' ends are covalently joined to form a closed continuous loop. They are resistant to digestion by EXORIBONUCLEASES.	Circular Intronic RNA,Circular RNA,Circular RNAs,Closed Circular RNA,ciRNA,circRNA,circRNAs,Circular RNA, Closed,Intronic RNA, Circular,RNA, Circular Intronic,RNA, Closed Circular,RNAs, Circular
D012313	RNA	A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)	RNA, Non-Polyadenylated,Ribonucleic Acid,Gene Products, RNA,Non-Polyadenylated RNA,Acid, Ribonucleic,Non Polyadenylated RNA,RNA Gene Products,RNA, Non Polyadenylated