Fig. 1. circIgfbp2 is up-regulated in the TBI mice and H₂O₂-treated cells. Also, hsa_circ_0058195 is elevated in acute TBI patients and is involved in anxiety-like behaviors after TBI.

A, B The network map of the differential circRNAs-miRNAs-mRNAs genes regulatory network screening by DEG algorithm, showing the top 5 up-regulated circRNAs (sham group vs. TBI group) (|fold-change| > 2, Q < 0.01). Red: circRNAs; Green: miRNAs; Black: mRNAs. C Relative circIgfbp2 levels were measured by qRT-PCR in the sham and injured brain tissue 3 days after TBI. n = 5 mice per group. ****p < 0.0001, two-tailed t-test. D Relative circIgfbp2 levels in the H₂O₂-treated HT22 cells and control group. n = 3 replications, ***p < 0.001, two-tailed t-test. E Homology analysis between mice circIgfbp2 and human circRNAs. F The relative expression level of hsa_circ_0058195 in the serum of acute TBI patients, which was highly homologous to circIgfbp2, and up-regulated after TBI. n = 50 TBI patients, n = 20 volunteers as control, ****p < 0.0001, two-tailed t-test. G The anxiety-like behaviors were analyzed using the Self-Rating Anxiety Scale in patients 3 months after TBI. The scale score had a positive linear relationship with the expression of hsa_circ_0058195. n = 50 TBI patients, n = 20 volunteers as control, p = 0.0051. H The depression-like behaviors were analyzed using the Self-Rating Depression Scale in patients 3 months after TBI. The scale score had no linear relationship with the expression of hsa_circ_0058195. n = 50 TBI patients, n = 20 volunteers as control, p = 0.7519. I ROC curve in the evaluation of the diagnostic value of serum hsa_circ_0058195 for anxiety after TBI. Area under curve (AUC) = 0.7883; p = 0.0006. J Schematic representation of the circularization of Igfbp2 1-2 exons to form circIgfbp2. The results of Sanger sequencing of the spliced junction resulting from the divergent primers are shown. K The presence of circIgfbp2 was validated in HT22 cells by PCR and agarose gel electrophoresis (AGE). Divergent primers amplified circIgfbp2 from cDNA but not from gDNA. L CircIgfbp2, linear Igfbp, and GAPDH levels were detected by PCR and AGE treated with RNase R for 0 to 120 min. All data were represented as mean ± SEM.