RNF138 deficiency led to exacerbated colitis severity and metabolic vulnerability in intestinal epithelial cells, correlating with reduced RNF138 expression in UC patients.
RNF138 protects intestinal epithelial cells from metabolic and inflammatory stress, suggesting it as a potential early interventional target for ulcerative colitis.
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Abstract Background The pathogenesis of ulcerative colitis (UC) involves complex interactions between dietary metabolites and inflammatory mediators. Increased intake of unsaturated fatty acids is considered a critical stressor. Although current UC therapies primarily target inflammatory responses, effective interventions preventing initial epithelial injury remain elusive. Methods An E3 siRNA library was screened in cells stimulated with arachidonic acid (AA) and interferon-γ (IFN-γ) to identify stress-responsive regulators. Results were integrated with UC transcriptomic datasets. RNF138-knockout (RNF138-/-) HCT116 cells and intestinal epithelial specific Rnf138-deficient mice (Rnf138ΔIEC) were generated. Responses to lipid and inflammatory stress were assessed in vivo using AA gavage and DSS-induced colitis. Cell death, oxidative stress, and mitochondrial activity were evaluated via CCK-8 assay, flow cytometry, ROS/MDA assays, and Seahorse XF analysis. Metabolic alterations were defined through transcriptomic and metabolomic profiling. Results Functional screening identified a synergistic cytotoxic effect of IFN-γ and AA on intestinal epithelial cells (IECs), revealing RNF138 as a key protective factor. RNF138 deficiency markedly sensitized HCT116 cells to IFN-γ and AA treatment. Furthermore, epithelial specific Rnf138 deletion exacerbated colitis severity in AA-gavaged DSS-colitis models, confirming its essential role in epithelial resilience. Transcriptomic and ultrastructural analyses revealed profound mitochondrial dysfunction in RNF138-/- cells, characterized by reduced KEGG enrichment of mitochondrial complexes, shrunken mitochondria, fragmented cristae, and elevated ROS/MDA levels. Seahorse XF analysis demonstrated diminished oxygen consumption alongside a compensatory increase in glycolysis, indicating a metabolic shift from oxidative phosphorylation to anaerobic metabolism. Upregulation of PTGS2 and SLC7A11 reflected heightened inflammatory signaling and redox imbalance, potentially increasing susceptibility to disulfidptosis. RNF138-/- cells exhibited significant vulnerability to glucose deprivation, which was reversed by exogenous glucose supplementation. Non-targeted metabolomics revealed global suppression of the pentose phosphate pathway, highlighting impaired metabolic buffering as a critical vulnerability. Notably, RNF138 expression was significantly reduced in tissues from UC patients and negatively correlated with disease activity, underscoring its translational relevance. Conclusion RNF138 was identified as a key regulator of intestinal epithelial metabolic homeostasis during combined lipid and inflammatory stress, highlighting its substantial potential as an early interventional target for UC. References: 1 Liu X, Olszewski K, Zhang Y, et al. Cystine transporter regulation of pentose phosphate pathway dependency and disulfide stress exposes a targetable metabolic vulnerability in cancer. Nat Cell Biol. 2020;22(4):476-486. doi:10.1038/s41556-020-0496-x 2 de Silva PS, Olsen A, Christensen J, et al. An association between dietary arachidonic acid, measured in adipose tissue, and ulcerative colitis. Gastroenterology. 2010;139(6):1912-1917. doi:10.1053/j.gastro.2010.07.065 3 Liao P, Wang W, Wang W, et al. CD8+ T cells and fatty acids orchestrate tumor ferroptosis and immunity via ACSL4. Cancer Cell. 2022;40(4):365-378.e6. doi:10.1016/j.ccell.2022.02.003 4 Lu Y, Huang R, Ying J, et al. RING finger 138 deregulation distorts NF-кB signaling and facilities colitis switch to aggressive malignancy. Signal Transduct Target Ther. 2022;7(1):185. Published 2022 Jun 13. doi:10.1038/s41392-022-00985-1 Conflict of interest: Ms. Zhang, Yiyao: No conflict of interest Zhu, Yalong: No conflict of interest Yu, Si: No conflict of interest Huang, Jingyi: No conflict of interest Yun, Longxi: No conflict of interest Liu, Changzheng: No conflict of interest Li, Yue: No conflict of interest
Zhang et al. (Thu,) reported a other. RNF138 deficiency led to exacerbated colitis severity and metabolic vulnerability in intestinal epithelial cells, correlating with reduced RNF138 expression in UC patients.