Mitochonic Acid 5 (MA-5) Facilitates ATP Synthase Oligomerization and Cell Survival in Various Mitochondrial Diseases

Mitochondrial dysfunction increases oxidative stress and depletes ATP in a variety of disorders. Several antioxidant therapies and drugs affecting mitochondrial biogenesis are undergoing investigation, although not all of them have demonstrated favorable effects in the clinic. We recently reported a therapeutic mitochondrial drug mitochonic acid MA-5 (Tohoku J. Exp. Med., 2015). MA-5 increased ATP, rescued mitochondrial disease fibroblasts and prolonged the life span of the disease model “Mitomouse” (JASN, 2016). To investigate the potential of MA-5 on various mitochondrial diseases, we collected 25 cases of fibroblasts from various genetic mutations and cell protective effect of MA-5 and the ATP producing mechanism was examined. 24 out of the 25 patient fibroblasts (96%) were responded to MA-5. Under oxidative stress condition, the GDF-15 was increased and this increase was significantly abrogated by MA-5. The serum GDF-15 elevated in Mitomouse was likewise reduced by MA-5. MA-5 facilitates mitochondrial ATP production and reduces ROS independent of ETC by facilitating ATP synthase oligomerization and supercomplex formation with mitofilin/Mic60. MA-5 reduced mitochondria fragmentation, restores crista shape and dynamics. MA-5 has potential as a drug for the treatment of various mitochondrial diseases. The diagnostic use of GDF-15 will be also useful in a forthcoming MA-5 clinical trial

Dynamic measurement of oxidase activity based on oxygen consumption in open systems

Oxidases catalyze the oxidation of a variety of substrateswith the concomitant reduction of molecular oxygen as a final electron acceptor. UV-visible spectrophotometry is a simple and high-throughput method commonly used to measure oxidase activities. However, drawbacks such as light scattering exist especially concerning the activity assessment of enzymes immobilized on supports. Monitoring of the universal cosubstrate O2 circumvents these drawbacks. This study aimed at developing a methodology that allows activity measurement of many types of oxidases based on O2 consumption applicable to various open systems. Dissolved oxygen in the reaction medium was monitored by an O2 sensor and the reaction rate was deducedfrom the O2 mass balance equation correcting for atmospheric diffusion. Common activity units (μMproduct min−1 or U/L) could be subsequently derived using calibration curves. The sensitivity of the method toward temperature, atmospheric pressure, and ionic strength variations was evaluated, and made it possible to define operating windows for the simplification of the proposed methodology