Redox modifications of cysteine in the liver of type 2 diabetes mellitus — ASN Events
  1. Schedule
  2. Lunch & Poster Session One
  3. Redox modifications of cysteine in the liver of type 2 diabetes mellitus

Redox modifications of cysteine in the liver of type 2 diabetes mellitus (#131)

Desmond K Li 1 , Lauren E Smith 2 , Joel A Cain 1 , Jana Paulech 1 , Stuart J Cordwell 1 2 , Melanie Y White 1 2
  1. School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
  2. Discipline of Pathology, School of Medical Sciences, The University of Sydney, Sydney, NSW, Australia

Reactive oxygen species (ROS) and associated redox modifications have normal physiological roles in signalling but are also implicated in a number of pathologies. Oxidative stress associated with type 2 diabetes mellitus (T2DM) has been attributed to increased generation/reduced clearance of ROS in insulin sensitive tissues including the liver1. During oxidative stress, proteins undergo redox modifications through the thiols of cysteine, which may alter structure, functionality and signalling pathways. To determine proteins of the liver which undergo redox modifications with T2DM, we investigated a number of associated metabolic disorders using redox proteomics. Rats were subjected to a high fat diet (HFD) to induce peripheral insulin resistance, as well as streptozotocin (STZ) to create β cell dysfunction, thereby generating the T2DM pathology. Rats treated with only HFD or STZ were utilised to analyse the pre-diabetic state. To enrich low abundance redox modified peptides, thiol disulfide exchange was utilised for reversibly modified cysteines2 with quantitation by iTRAQ. Strong cation exchange was used to select for irreversibly modified cysteines3, combined with label-free quantitation. Enriched and non-captured fractions were subjected to 2D-LC to increase depth of coverage before identification by tandem mass spectrometry. Using this approach, the TripleTOF 5600 (AB Sciex) identified 8038 redox-modified sites in the liver proteome, with over 2223 sites quantified in response to T2DM (HFD+STZ). Oxidative modifications to proteins which maintain redox balance suggests dysregulation, contributing to oxidative stress in T2DM. Observed changes in enzymes involved in glucose metabolism suggest a role of redox modifications in glucose utilisation/production. Modifications to enzymes in fatty acid metabolism correlate with the hyperlipidemia associated with T2DM. Many proteins showed increased levels of irreversible oxidative modifications contributing to protein damage. Changes in the redox status of these proteins could be indicative of these protein species prone to oxidative damage, contributing to pathogenesis or a level of cellular regulation in response to the metabolic disturbance.

  1. Hoffman, A. (2009) Insulin action mechanism for redox signaling in the cell cycle: Its alterations in diabetes. Free Radical Biology and Medicine 47, 1093-1097
  2. Paulech, J., Solis, N., Edwards, A. V., Puckeridge, M., White, M. Y., and Cordwell, S. J. (2013) Large-scale capture of peptides containing reversibly oxidized cysteines by thiol-disulfide exchange applied to the myocardial redox proteome. Analytical Chemistry 85, 3774-3780
  3. Paulech, J., Liddy, K. A., Engholm-Keller, K., White, M. Y., and Cordwell, S. J. Global analysis of myocardial peptides containing cysteines with irreversible sulfinic and sulfonic acid post-translational modifications. In review