Circular RNAs in human and vertebrate neural retinas

Circular RNAs (circRNAs) belong to an endogenous class of RNA molecules with both ends covalently linked in a circle. Although their expression pattern in the mammalian brain has been well studied, the characteristics and functions of circRNAs in retinas remain unknown. To reveal the whole expression profiles of circRNAs in the neural retina, we investigated retinal RNAs of human, monkey, mouse, pig, zebrafish and tree shrew and detected thousands of circRNAs showing conservation and variation in the retinas across different vertebrate species. We further investigated one of the abundant circRNAs, circPDE4B, identified in human retina. Silencing of circPDE4B significantly inhibited the proliferation of human A549 cells. Functional assays demonstrated that circPDE4B could sponge miR-181C, thereby altering the cell phenotype. We have explored the retinal circRNA repertoires across human and different vertebrates, which provide new insights into the important role of circRNAs in the vertebrate retinas, as well as in related human diseases.

环状RNA（circular RNAs，circRNAs）是一类内源性RNA分子，其两端以共价键结合形成环状结构。尽管学界已对环状RNA在哺乳动物脑组织中的表达模式开展了充分研究，但视网膜内环状RNA的特性与功能仍未明确。为解析神经视网膜内环状RNA的完整表达谱，本研究对人、猴、小鼠、猪、斑马鱼及树鼩的视网膜RNA进行了系统分析，鉴定到数千条在不同脊椎动物视网膜中兼具保守性与差异性的环状RNA。本研究进一步针对在人视网膜中鉴定出的高丰度环状RNA之一circPDE4B展开了深入研究。沉默circPDE4B可显著抑制人A549细胞的增殖。功能实验证实，circPDE4B可通过海绵吸附miR-181C，进而改变细胞表型。本研究解析了人类及不同脊椎动物的视网膜环状RNA组库，为阐明环状RNA在脊椎动物视网膜及相关人类疾病中的重要作用提供了全新的研究视角。