Metallothionein prevents diabetes-induced cardiac pathological changes, likely via the inhibition of succinyl-CoA:3-ketoacid coenzyme A transferase-1 nitration at Trp³⁷⁴

Abstract

L. Metallothionein prevents diabetes-induced cardiac pathological changes, likely via the inhibition of succinyl-CoA:3-ketoacid coenzyme A transferase-1 nitration at Trp 374 . Am J Physiol Endocrinol Metab 304: E826 -E835, 2013. First published February 26, 2013 doi:10.1152/ajpendo.00570.2012.-We previously demonstrated that metallothionein (MT)-mediated protection from diabetesinduced 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 diabetes; cardiac pathological changes; metallothionein; SCOT; 3-nitrotyrosine DIABETES HAS BECOME one of the most prolific public health issues worldwide (25). Mechanistic studies have revealed that oxidative and nitrosative stress are major causes of diabetes and its complications (4, 13). Overproduced superoxide has been shown in diabetic individuals to interact with nitric oxide, forming the peroxynitrite (ONOO Ϫ ) free radical that mediates biomacromolecule nitration and can ultimately lead to organ dysfunction. The covalent product of tyrosine nitration, 3-nitrotyrosine (3-NT), serves as an index of peroxynitrite-induced protein damage and is used in clinic as a convenient quantitative biomarker of cardiovascular risk (measured in free and protein-bound forms in human plasma) (23). Moreover, overproduction of superoxide and associated peroxynitrite has been implicated in the development of diabetic cardiomyopathy (4, 20, 28). Therefore, a promising approach to prevent the development of diabetic complications will include the prevention of oxidative and nitrosative stress (2).The well-established and widely used animal model of type 1 diabetes induced by streptozotocin (STZ) has several nitrated molecules in the cardiac tissue. The majority of these nitrated molecules are mitochondrial proteins with known functions in cellular energy metabolism and oxygen oxidation (26,27,29). However, whether the nitration of these mitochondrial proteins contributes to the development of diabetic cardiomyopathy remains largely unknown.The cysteine-rich protein metallothionein (MT) is a ubiquito...

Diabetic cardiomyopathy and its mechanisms: Role of oxidative stress and damage

“…However, only Trp 374 showed 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 Trp 374 ; In another study, using LC/MS analysis we showed that diabetes increased tyrosine nitration of the ATP synthase α subunit at Tyr271, Tyr311 and Tyr476, and the β subunit at Tyr269 and Tyr508, and also significantly reduced ATP synthase activity by ~32% (Figure ). These changes were not observed in MT‐TG diabetic mice.…”

“…3‐Ketoacid CoA transferase‐1 ( SCOT ) protein expression, nitration, and activity in the hearts of diabetic wild‐type ( WT ) and cardiac‐specific metallothionein‐overexpressing transgenic ( MT ‐ TG ) mice. Type 1 diabetes was induced with a single dose of streptozotocin ( STZ ) in Friend virus B‐type (wild‐type) and cardiac‐specific overexpression of MT ‐ TG mice used for the study. (a) Cardiac tissues collected at the indicated post‐induction times were examined by western blot to show changes in SCOT expression.…”

“…* P < 0.05, ** P < 0.01, *** P < 0.001. This work by the authors has been published. CON , control; GAPDH , glyceraldehyde‐3‐phosphate dehydrogenase.…”

High-Glucose Inhibits Human Fibroblast Cell Migration in Wound Healing via Repression of bFGF-Regulating JNK Phosphorylation

“…The bFGF supply eliminated HG-induced ROS accumulation, but bFGF with PD173074 diminished efficacy of bFGF to eliminate ROS buildup. Protein nitrations are associated with oxidative stress and lead to complications of diabetes [21], [23]. However, diabetes-induced specific protein nitrosative modifications in fibroblast cells have not been reported.…”

“…Mechanistic studies on DM effects have revealed that major causes and complications of DM are oxidative stress and nitrations of its mediated protein [21]–[23]. However, the events of protein nitration in fibroblasts under diabetic conditions have not been reported.…”