Fig. 1

CircFTO is up-regulated in exosomes derived from RA-FLSs. (A) Representative images of exosomes derived from RA-FLSs and H-FLSs. (B) The particle size distribution of exosomes derived from RA-FLSs and H-FLSs was analyzed. (C) Western blot analysis was conducted to ascertain the expression levels of TSG101 and CD63, which are surface markers specific to exosomes. (D) A heatmap illustrating the top 10 differentially expressed circRNAs in exosomes was generated. (E) The expression levels of hsa_circ_0069492, hsa_circ_0005941, and hsa_circ_0001900 in exosomes were validated using qRT-PCR. (F) Sanger sequencing was employed to confirm the back-splicing structure of hsa_circ_0005941. (G) Following treatment with RNase R, qRT-PCR analysis aimed at determining circFTO and FTO expressions within RA-FSL cells was carried out. (H) The stability of circFTO and FTO mRNA at specified time points was assessed using an Actinomycin D assay. (I) The subcellular localization of circFTO in RA-FLSs and H-FLSs was determined using FISH assay. (J) The expression level of circFTO in both RA-FLSs and H-FSLs was quantified through qRT-PCR analysis. (K) qRT-PCR analysis detected the expression level of circFTO in synovial tissues from patients with RA as well as normal individuals. Data are presented as mean ± SD, n = 3, ***p < 0.001