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Noncoding RNAs have been found to play important roles in DNA damage repair, whereas the participation of circRNA remains undisclosed. Here, we characterized ciRS-7, a circRNA containing over 70 putative miR-7-binding sites, as an enhancer of miRISC condensation and DNA repair. Both in vivo and in vitro experiments confirmed the condensation of TNRC6B and AGO2, two core protein components of human miRISC. Moreover, overexpressing ciRS-7 largely increased the condensate number of TNRC6B and AGO2 in cells, while silencing ciRS-7 reduced it. Additionally, miR-7 overexpression also promoted miRISC condensation. Consistent with the previous report that AGO2 participated in RAD51-mediated DNA damage repair, the overexpression of ciRS-7 significantly promoted irradiation-induced DNA damage repair by enhancing RAD51 recruitment. Our results uncover a new role of circRNA in liquid-liquid phase separation and provide new insight into the regulatory mechanism of ciRS-7 on miRISC function and DNA repair. [ABSTRACT FROM AUTHOR]

Iodine efficiently catalyzes the one-pot, three-component reaction of aryl aldehyde, 2-naphthol, and cyclic 1,3-dicarbonyl compound under solvent-free conventional heating conditions to afford the corresponding 12-aryl-8,9,10,12-tetrahydro-benzo[a]xanthen-11-one derivatives. The present approach offers several advantages such as shorter reaction times, good yields, low cost, and mild reaction conditions. [ABSTRACT FROM AUTHOR]