Inhibition of Pathological Mitochondrial Fission Restores DSS Associated Respiratory Impairments in an Intestinal Epithelial Cell Line

Abstract

SignificanceRecent evidence has shown that mitochondrial dynamics and more specifically, mitochondrial fission, play an important role in numerous disease of energy intensive tissues. In particular, mitochondrial fission mediated by the enzyme dynamin related protein‐1 (DRP1) and the receptor fission protein‐1 (Fis1) is associated with reduced ATP production, ROS generation and inflammation. Examination of this interaction and corresponding pathological mitochondrial fission has yet to be examined in the colon in the context of inflammatory bowel disease.ObjectiveTo identify if a common murine colitis agent, dextran sodium sulfate (DSS), induces mitochondrial respiration dysfunction and if the novel peptide (P110), can restore these deficiencies by inhibiting DRP1 and Fis1 mediated fission.DesignThe murine intestinal epithelial cell line, IEC4.1, was separated into control, P110, DSS and DSS + P110. Cell were seeded and allowed to incubate for 24 hrs before receiving their respective treatments and further incubation for another 24hrs.MethodsOptimization of both DSS (1–2w./v.%) and P110 (0.5–1.5 uM) dosage and exposure time was performed with the AlamarBlue cell proliferation assay. Basal, mitochondrial complex and maximal respiratory activity were assessed using the Oxygraph‐2k (OROBOROS Instruments, Austria). Respiratory function of cells under various substrate pathways was also examined.ResultsDSS (2%) significantly reduced cell proliferation compared to control and P110 groups (p<0.05). Administration of P110 in 2% DSS cells dose dependently increased cell proliferation, with 1.5 uM P110 exhibiting cell proliferation similar to control. Analysis of mitochondrial complexes revealed that DSS reduced basal, complex I, II, IV and maximal activity (p<0.05). P110 was found to restore DSS associated respiratory deficiencies in complex I, II and IV (p<0.05).ConclusionThis study highlights novel findings regarding the role of mitochondrial fission in a model system of epithelial dysfunction. Importantly, we show i) evidence that DRP1 and Fis1 mediated fission hold potential; pathological consequences in energetically demanding tissues like the colon and ii) P110 treatment reduces DSS induced damage and its associated respiratory deficiencies. These results suggest mitochondrial dysfunction could be intricately involved in gut barrier deterioration seen in inflammatory bowel disease.Support or Funding InformationCrohn's and Colitis Canada. The authors wish to thank Daria Mochly‐Rosen for donating P110.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.