生命科学学院学术报告
Title: Genome-wide characterization of circular RNAs
Speaker: Dr. Li Yang,  
Principal Investigator, 
CAS-MPG Partner
Institute for Computational Biology, SIBS, CAS
Time: 09:30-10:30, Friday, December 08, 2017
Location: Room 311, Wang Ke-Zhen Building, Peking University
Abstract:
Eukaryotic pre-mRNAs undergo splicing to remove intragenic regions (introns) and ligate expressed regions (exons) together. Unlike exons in the mature mRNAs for translation, introns that are spliced out of pre-mRNAs were generally believed to lack function and to be degraded. However, recent studies have revealed that a large group of spliced introns can escape complete degradation and are processed to generate noncoding RNAs (ncRNAs), including different types of small RNAs, long noncoding RNAs and at least two types of circular RNAs. On the one hand, circular intronic RNAs (ciRNAs) are produced from excised intron lariats that fail to be debranched after splicing, leading to a covalent circle with 2′,5′-phosphodiester bond between 5′ splice donor site and the branchpoint site. On the other hand, exonic sequences can be also back-spliced from mRNA precursors to form stable circular RNAs (circRNAs) with 3′,5′-phosphodiester bond. With the advent of specific biochemical and computational approaches, a large number of circRNAs have been identified in various cell lines and across different species. Recent studies have uncovered that back-splicing requires canonical spliceosomal machinery and can be facilitated by both complementary sequences and specific protein factors. The competition of putative RNA pairs by complementary sequences across different sets of introns leads to previously under-appreciated alternative back-splicing selection. Together, these findings not only expand the ever-growing repertoire of ncRNAs that originate from different genomic regions, but also reveal the unexpected trancriptomic complexity and functional capacity of eukaryotic genomes.
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