Pharmacoproteomics reveals the mechanism of Chinese dragon's blood in regulating the RSK/TSC2/mTOR/ribosome pathway in alleviation of DSS-induced acute ulcerative colitis.

Chinese dragon's blood (CDB), a crude drug extracted from Dracaena cochinchinensis (Lour.) S.C. Chen, has been historically applied for the treatment of various diseases, including ulcerative colitis (UC). Unfortunately, the underlying molecular mechanism remains unclear. In this paper, the effects of CDB treatment on a mouse model of acute UC and proteomic variation in colonic tissue were investigated. The acute UC model in Balb/c mice was induced by administration of 2.5% (wt/vol) dextran sulfate sodium (DSS) in drinking water for 8 days. After the mice with UC were intragastrically administered CDB and intraperitoneally injected with rapamycin (RAPA, a specific inhibitor of mTORC1), the disease activity index (DAI) and histopathological score were recorded. An isobaric tags for relative and absolute quantification (iTRAQ) based LC-MS/MS proteomic technique was adopted to identify the differentially expressed proteins (DEPs) in colonic tissue. Bioinformatics analysis was used to discover the molecular functions and pathways of the DEPs. Finally, Western blot analysis and immunohistochemistry were used to verify the protein expression. The results showed that CDB treatment significantly ameliorated the symptoms and intestinal damage in acute UC, while RAPA treatment led to severe symptoms and intestinal damage. A total of 489 DEPs were reversed in the control check (CK) group and the CDB group. Most DEPs were enriched in the structural constituents of ribosomes and the ribosome pathway. CDB treatment significantly upregulated the expression of the mTOR, p-mTOR and p70S6K proteins and downregulated the expression of the Akt, p-Akt, and p4EBP1 proteins. However, RAPA treatment, unlike CDB, did not return the levels of mTOR, Akt, and their phosphorylated forms to nearly normal. In conclusion, the dysfunction of the mTOR/ribosome pathway resulting in the inhibition of ribosome synthesis played an important role in the development of acute UC in mice, and CDB, but not RAPA, was an alternative drug for the treatment of acute UC by enhancing ribosome synthesis via the mTOR/ribosome pathway and further promoting protein synthesis.