Fig. 4

circERBB2 promotes rDNA transcription in the nucleolus. a FISH + IF double staining showed nucleolar localization of circERBB2. Scale bar: 20 μm. b circERBB2 accumulated to the nucleoli. Total RNA from SGC-996 cells was separated into cytoplasmic, nuclear, and nucleolar fractions and analyzed by semi-quantitative PCR. c qPCR determined relative abundance of rRNAs after silencing of circERBB2, and steady level of 45S pre-rRNA decreased significantly (n = 3). d Luciferase reporter assay showed that silencing of circERBB2 decreased rDNA promoter activity (n = 3). e qPCR assay showed that relative steady level of 45S increased significantly with OE of circERBB2 (n = 3). f Luciferase reporter assay showed that OE of circERBB2 increased rDNA promoter activity (n = 3). Quantitative data from three independent experiments was presented as mean ± SD (error bars). P-values were determined by paired, two-tailed two sample t-test. *: p < 0.05; **: p < 0.01