[Novel role of intracellular ATP in obesity pathology]

ATP is an important energy source for cells. Traditionally, intracellular ATP levels are believed to be relatively stable and will not rise consistently in the physiological conditions. However, new studies suggest that ATP levels may rise in multiple tissues under the condition of energy surplus contributing to the metabolic disorders in obesity. However, the molecular mechanism of ATP elevation remains unknown in obesity except the increase in energy supply. Based on our experimental results and the findings reported in the literature, we discuss the cellular and molecular mechanisms by which ATP levels are regulated in cells by multiple factors, including superoxide ions, mitochondrial flash, antioxidants, anti-apoptotic molecule Bcl-xL, AMP-activated protein kinase (AMPK) and metformin. Contribution of these factors to the alteration of ATP set-point will be discussed together with their impact on insulin resistance in type 2 diabetes mellitus. With a focus on the energy surplus in obesity, we explore the mechanism of insulin resistance induced by ATP elevation and provide an answer to the contradiction between the new experimental results and the traditional viewpoint of intracellular ATP. We propose that elevation of intracellular ATP may lead to metabolic disorder in obesity through activation of a feedback mechanism that inhibits mitochondrial function.