: A drug repurposing approach to target candidate deubiquitinases in chronic inflammation.

Abstract

Inflammation is a process that is triggered by encountering various antigens such as abnormal cells, bacteria, and viruses. However, unresolved inflammation might lead to chronic diseases and tissue damage. The molecular mechanism through which chronic inflammation, particularly mechanical injury-induced inflammation, lead to tissue damage remain undefined. Previous evidence from our group found that injury to the connective tissue, triggers strong inflammatory response. Our group identified the ubiquitin system and DUBs enzymes as strong upstream regulators of these inflammatory signaling pathways. Using pulldown assay and mass spectrometric analysis, our groups identified USP14, USP5, UCHL1, UCHL3 and YOD1 as highly active DUBs in damaged cartilage. Therefore, I hypothesized that USP5, USP14, UCHL1, UCHL3 and YOD1 DUBs are playing a significant role in injury-induced inflammation and tissue damage as well as NFKB activity in the zebrafish larvae. The inhibition of these DUBs might provide new treatment strategy for inflammation. Previous report in the literature repurposed a list of FDA- approved drugs and found that they possess anti-inflammatory activity by inhibiting neutrophil migration to the injury site. Based on this finding, I tested the same drug list on these recombinant DUBs using DUB activity assays and on the NFKB activity in the zebrafish larvae model, and I found that niflumic acid and alfuzosinHCl are strong inhibitors toward UCHL1. Acetohexamide and methyldopa were extremely potent inhibitors for UCHL3 while. Amodiaquin was the top inhibitor against USP5. This project also found that acetohexamide and methyldopa are very strong inhibitors for injury induced NFKB activity in the zebrafish larvae. I concluded that acetohexamide and methyldopa might reduce the inflammation through inhibition of the DUBs activity.