Fig. 6
circBIRC6 augments SUMOylation of XRCC4 at K115 residue. (A) Western blot analysis illustrating cytoplasmic and nuclear distribution of XRCC4 in Panc-1 cells treated with EVs isolated from CAFs and the SUMOylation inhibitor (2-D08). (B) Co-immunoprecipitation (Co-IP) study presenting the SUMO1 binding on XRCC4 in Panc-1 cells treated with EVs from CAFs transfected with lenti-circBIRC6-shRNA or lenti-NC-shRNA. (C) Co-IP assays elucidating the interaction between XRCC4 and SAE1 in Panc-1 cells treated with EVs from CAFs transduced with lenti-circBIRC6-shRNA or lenti-NC-shRNA. (D) Co-IP analysis of SUMO1 binding on XRCC4 in Panc-1 cells transfected with SAE1 siRNA and treated with EVs from CAFs. (E) Western blot analysis of cytoplasmic and nuclear distribution of XRCC4 in Panc-1 cells transfected with SAE1 siRNA and treated with EVs from CAFs. (F) Schematic depiction of the predicted SUMO1 binding sites on XRCC4 obtained via GST-SUMO. (G) Sequence alignment of XRCC4 homologs across various species. (H) Sequencing evaluation of the XRCC4K115R and XRCC4K210R mutations. (I) Co-IP assays assessing the SUMO1 binding sites on XRCC4. (J) Western blot analysis of cytoplasmic and nuclear distribution of XRCC4 in Panc-1 cells transfected with XRCC4 K115R or XRCC4K210R mutations and treated with EVs from CAFs. (K) Representative image and quantification of apoptosis in Panc-1 cells transfected with XRCC4K115R mutations and treated with EVs from CAFs using flow cytometry. n.s., not significant. Data are expressed as mean ± SD. **p < 0.01