Weitao Cong1,2, Weide Ma1,3,2, Ting Zhao1,2, Zhongxin Zhu1,2, Yuehui Wang4, Yi Tan1,5, Xiaokun Li1,2, Litai Jin1,2, Lu Cai1,5
1Chinese-American Research Institute for Diabetic Complications, Wenzhou Medical College, Zhejiang, China;
2School of Pharmaceutical Science, Wenzhou Medical College, Wenzhou, China
3Laboratory of Gynecology and Obstetrics, People's Hospital of Wenzhou, Zhejiang, China;
4Department of Cardiovascular Disorders, the Second Hospital of Jilin University, Changchun, China; and
5Kosair Children's Hospital Research Institute, Department of Pediatrics, University of Louisville School of Medicine, Louisville, Kentucky
Tóm tắt
We previously demonstrated that metallothionein (MT)-mediated protection from diabetes-induced pathological changes in cardiac tissues is related to suppression of superoxide generation and protein nitration. The present study investigated which diabetes-nitrated protein(s) mediate the development of these pathological changes by identifying the panel of nitrated proteins present in diabetic hearts of wild-type (WT) mice and not in those of cardiac-specific MT-overexpressing transgenic (MT-TG) mice. At 2, 4, 8, and 16 wk after streptozotocin induction of diabetes, histopathological examination of the WT and MT-TG diabetic hearts revealed cardiac structure derangement and remodeling, significantly increased superoxide generation, and 3-nitrotyrosine accumulation. A nitrated protein of 58 kDa, succinyl-CoA:3-ketoacid CoA transferase-1 (SCOT), was identified by mass spectrometry. Although total SCOT expression was not significantly different between the two types of mice, the diabetic WT hearts showed significantly increased nitration content and dramatically decreased catalyzing activity of SCOT. Although SCOT nitration sites were identified at Tyr76, Tyr117, Tyr135, Tyr226, Tyr368, and Trp374, only Tyr76and Trp374were found to be located in the active site by three-dimensional structure modeling. However, only Trp374showed a significantly different nitration level between the WT and MT-TG diabetic hearts. These results suggest that MT prevention of diabetes-induced pathological changes in cardiac tissues is most likely mediated by suppression of SCOT nitration at Trp374.
