The article by Chen and Yang (2015) provides a comprehensive review of the regulation of circular RNA (circRNA) biogenesis. Unlike linear RNAs, circRNAs are characterized by their covalently closed loop structures, lacking 5' caps and 3' tails. This unique structure has led to the underestimation of their existence in previous transcriptome analyses. Recent advancements in biochemical and computational methods have revealed a large number of circRNAs from back-spliced exons (circRNAs) across various cell lines and species. The review highlights the importance of canonical spliceosomal machinery and the role of complementary sequences and specific protein factors in back-splicing. It discusses the competition between splicing and back-splicing, emphasizing that both processes are essential for circRNA formation. The article also explores the regulatory mechanisms that govern this competition, including cis-elements and trans-factors. Key points include: - The coupling of canonical splicing and back-splicing, with both processes being necessary for circRNA formation. - The role of RNA pairing across flanking introns and protein factors in promoting back-splicing. - The discovery of multiple circRNAs from a single gene locus, a phenomenon known as alternative circularization. - The involvement of circRNAs in gene regulation, such as sponge effects on microRNAs and regulation of RNA Pol II transcription. The authors conclude by noting the complex and dynamic nature of circRNA biogenesis, suggesting that further research is needed to fully understand the functions of these molecules in physiological and pathological conditions.The article by Chen and Yang (2015) provides a comprehensive review of the regulation of circular RNA (circRNA) biogenesis. Unlike linear RNAs, circRNAs are characterized by their covalently closed loop structures, lacking 5' caps and 3' tails. This unique structure has led to the underestimation of their existence in previous transcriptome analyses. Recent advancements in biochemical and computational methods have revealed a large number of circRNAs from back-spliced exons (circRNAs) across various cell lines and species. The review highlights the importance of canonical spliceosomal machinery and the role of complementary sequences and specific protein factors in back-splicing. It discusses the competition between splicing and back-splicing, emphasizing that both processes are essential for circRNA formation. The article also explores the regulatory mechanisms that govern this competition, including cis-elements and trans-factors. Key points include: - The coupling of canonical splicing and back-splicing, with both processes being necessary for circRNA formation. - The role of RNA pairing across flanking introns and protein factors in promoting back-splicing. - The discovery of multiple circRNAs from a single gene locus, a phenomenon known as alternative circularization. - The involvement of circRNAs in gene regulation, such as sponge effects on microRNAs and regulation of RNA Pol II transcription. The authors conclude by noting the complex and dynamic nature of circRNA biogenesis, suggesting that further research is needed to fully understand the functions of these molecules in physiological and pathological conditions.