YO-03 - Acute pancreatitis and cystinosis as experimental models of disulfide stress characterized by protein cysteinylation

Abstract

Disulfide stress is a specific type of oxidative stress that is associated with protein cysteinylation. The aim of this research was to characterize experimental models of disulphide stress. Thus, the redox status of free thiols and protein cysteinylation was studied in acute pancreatitis as an in vivo model of inflammation and in cystinosis an in vitro model of cystine accumulation due to its dysfunctional lysosomal transport. Cystine and homocystine levels, and protein cysteinylation rose after taurocholate-induced acute pancreatitis. Oxidation of cysteines in mitochondrial sulfide quinone oxidoreductase and 60S ribosomal protein L7a was observed. Cysteinylated albumin was also detected. Serine/threonine protein phosphatase PP2Ac, and Keap-1 were identified as targets of disulfide stress in acute pancreatitis. PP2Ac exhibited an intramolecular disulfide that was detected by diagonal electrophoresis. Silencing of PP2Ac in 266 pancreatic cells triggered up-regulation of IL-6 under basal conditions and enhanced TNF-a-induced expression of Cxcl1 and Tnf-a. Silencing of lysosomal transporter, cystinosin, triggered an increase in cystine levels and cysteinylation in PANC-1 cells. In conclusion, disulfide stress triggers protein cysteinylation associated with oxidation of the cysteine/cysteine pair in acute pancreatitis and cystinosis. PP2A is a major target in acute inflammation.