Pyruvate dehydrogenase has a major role in mast cell function and its activity is regulated by mitochondrial MITF

Abstract

Abstract Background We have recently observed that OXPHOS mediated ATP production is essential for mast cell function. Pyruvate dehydrogenase (PDH) is the main regulator of the Krebs cycle and is located upstream to the electron transport chain. However, the role of PDH in mast cell function has not been described. Microphthalmia transcription factor (MITF) regulates the development, number and function of mast cells. The localization of MITF to the mitochondria and its interaction with mitochondrial proteins has not been explored. Objective To explore the role played by PDH in mast cell exocytosis and to determine whether MITF is localized in the mitochondria and is involved in the regulation of PDH activity. Methods Experiments were performed in vitro using human and mouse mast cells and RBL cells and in vivo in mice. The effect of PDH inhibition on mast cell function was examined. PDH interaction with MITF was measured before and after immunological activation. Furthermore, mitochondrial localization of MITF and its effect on PDH activity were determined. Results PDH is essential for immunologically mediated degranulation of mast cells. Following activation PDH is serine dephosphorylated. In addition, we show for the first time that MITF is partially located in the mitochondria and interacts with PDH. This interaction is dependent on the phosphorylation state of PDH. Furthermore, mitochondrial MITF regulates PDH activity. Conclusion The association of mitochondrial MITF with PDH emerges as an important regulator of mast cell function. Our findings indicate that PDH could arise as a new target for the manipulation of allergic diseases.