Recent evidence suggested muscular free fatty acids (FFA) accumulation might be responsible for mitochondrial dysfunction in type 2 diabetes mellitus (T2DM). Reactive oxygen species (ROS) and/or reactive nitrogen species (RNS) directly oxidize and damage DNA, proteins, and lipids and play a key role in the pathogenesis of T2DM. ROS/RNS may cause various types of oxidative modifications on specific proteins;such modifications, if irreversible, may lead to severe failure of biological functions, accumulation of damaged proteins and cell death. Identification of oxidatively modified proteins in mitochondria is important for understanding the relationship between protein oxidation, protein aggregation and development of T2DM. Recently, we have reported that targeting the DNA repair protein hOGG1 in mitochondria augments mitochondrial DNA (mtDNA) repair and enhances cellular survival following oxidative stress. The hypothesis to be tested is that mtDNA damage is involved in mitochondrial dysfunction and insulin resistance (IR) following FFA exposure in skeletal muscle. Improving mtDNA repair by expressing hOGG1 in mitochondria in skeletal muscle will diminish the generation of secondary ROS and thus reduce the proportion of oxidative modifications of specific mitochondrial proteins. This will increase mitochondrial protein function, and ultimately lead to enhanced mitochondrial function, increased insulin sensitivity, and cellular survival following exposure to FFA. This hypothesis will be tested through the pursuit of three specific aims. The first is to test using rat L6 skeletal muscle cells that FFA induced mtDNA damage, and consequently caused mitochondrial dysfunction, IR and apoptosis. Additionally, evaluate mtDNA damage and mitochondrial dysfunction in skeletal muscles isolated from a mouse model of T2DM (C57BL6 mice fed a high fat diet). The second is to determine whether targeting of hOGG1 into rat L6 skeletal cell mitochondria will decrease FFA- induced mtDNA damage and thus lead to enhanced insulin sensitivity, cellular survival and proliferation.
The third aim i s to determine the effect of reducing FFA-induced mtDNA damage through the overexpression of hOGG1 in mitochondria on ROS production and on subsequent oxidation of mitochondrial proteins following FFA-exposure to these cells. To complete this study we propose to make use of a new liquid chromatography tandem mass spectrometry (LC-MS/MS) approach.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
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Integrative Physiology of Obesity and Diabetes Study Section (IPOD)
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Laughlin, Maren R
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University of South Alabama
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Yuzefovych, Larysa V; LeDoux, Susan P; Wilson, Glenn L et al. (2013) Mitochondrial DNA damage via augmented oxidative stress regulates endoplasmic reticulum stress and autophagy: crosstalk, links and signaling. PLoS One 8:e83349
Yuzefovych, Larysa V; Musiyenko, Sergiy I; Wilson, Glenn L et al. (2013) Mitochondrial DNA damage and dysfunction, and oxidative stress are associated with endoplasmic reticulum stress, protein degradation and apoptosis in high fat diet-induced insulin resistance mice. PLoS One 8:e54059
Yuzefovych, Larysa V; Schuler, A Michele; Chen, Jemimah et al. (2013) Alteration of mitochondrial function and insulin sensitivity in primary mouse skeletal muscle cells isolated from transgenic and knockout mice: role of ogg1. Endocrinology 154:2640-9
Yuzefovych, Larysa V; Solodushko, Viktoriya A; Wilson, Glenn L et al. (2012) Protection from palmitate-induced mitochondrial DNA damage prevents from mitochondrial oxidative stress, mitochondrial dysfunction, apoptosis, and impaired insulin signaling in rat L6 skeletal muscle cells. Endocrinology 153:92-100
Yuzefovych, Larysa; Wilson, Glenn; Rachek, Lyudmila (2010) Different effects of oleate vs. palmitate on mitochondrial function, apoptosis, and insulin signaling in L6 skeletal muscle cells: role of oxidative stress. Am J Physiol Endocrinol Metab 299:E1096-105
Rachek, Lyudmila I; Yuzefovych, Larysa V; Ledoux, Susan P et al. (2009) Troglitazone, but not rosiglitazone, damages mitochondrial DNA and induces mitochondrial dysfunction and cell death in human hepatocytes. Toxicol Appl Pharmacol 240:348-54