Fig. 1

Upregulation of circular RNA METTL9 (circMETTL9) in rat cerebral cortex following traumatic brain injury (TBI). A Clustered heat map showing circRNAs differentially expressed in the cortex of TBI model rats compared to sham controls according to microarray analysis. B Volcano map showing the 74 circRNAs significantly upregulated and 68 circRNAs significantly downregulated by TBI. C KEGG pathway analysis suggesting that these differentially expressed circRNAs may regulate secondary injury following TBI via multiple signaling pathways. D GO analysis showing the possible functions of these differentially expressed circRNAs. E Sequencing results of seven selected circRNAs with differential expression. F qPCR validation of these seven selected circRNAs. *P < 0.05, **P < 0.01, ***P < 0.001 by Student’s t-test. G Four human circRNAs originating from the METTL9 gene with high homology to rat circMETTL9 according to BLAST searching of circBase. H Flowchart of circRNA screening for possible regulation by TBI