Evaluation of intramitochondrial ATP levels identifies G0/G1 switch gene 2 as a positive regulator of oxidative phosphorylation

• Published in: Proceedings of the National Academy of Sciences - PNAS 2014-01, Vol.111 (1), p.273-278
• Main Authors: Kioka, Hidetaka, Kato, Hisakazu, Fujikawa, Makoto, Tsukamoto, Osamu, Suzuki, Toshiharu, Imamura, Hiromi, Nakano, Atsushi, Higo, Shuichiro, Yamazaki, Satoru, Matsuzaki, Takashi, Takafuji, Kazuaki, Asanuma, Hiroshi, Asakura, Masanori, Minamino, Tetsuo, Shintani, Yasunori, Yoshida, Masasuke, Noji, Hiroyuki, Kitakaze, Masafumi, Komuro, Issei, Asano, Yoshihiro, Takashima, Seiji
• Format: Article
• Language: English
• Subjects: Adenosine triphosphatase; Adenosine Triphosphate - chemistry; Anaerobic conditions; Animals; Bioassays; Biological Sciences; Biosensing Techniques; Biosensors; Cattle; Cell Cycle Proteins - metabolism; Cell lines; Cell Survival; Cells; Fluorescence; G1 Phase; Gene expression; Genes, Switch; HEK293 Cells; HeLa Cells; Humans; Hypoxia; Mice; Microscopy, Confocal; Mitochondria; Mitochondria - metabolism; Myocardium; Myocytes, Cardiac - cytology; Oligomycins; Oligomycins - chemistry; Oligonucleotide Array Sequence Analysis; Oxidative Phosphorylation; Oxygen Consumption; Phosphorylation; Rats; Rats, Wistar; Recombinant Proteins - metabolism; Resting Phase, Cell Cycle; Stem cells; Switch genes; Time Factors
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1318547111

The oxidative phosphorylation (OXPHOS) system generates most of the ATP in respiring cells. ATP-depleting conditions, such as hypoxia, trigger responses that promote ATP production. However, how OXPHOS is regulated during hypoxia has yet to be elucidated. In this study, selective measurement of intramitochondrial ATP levels identified the hypoxia-inducible protein G0/G1 switch gene 2 (G0s2) as a positive regulator of OXPHOS. A mitochondria-targeted, FRET-based ATP biosensor enabled us to assess OXPHOS activity in living cells. Mitochondria-targeted, FRET-based ATP biosensor and ATP production assay in a semiintact cell system revealed that G0s2 increases mitochondrial ATP production. The expression of G0s2 was rapidly and transiently induced by hypoxic stimuli, and G0s2 interacts with OXPHOS complex V (F ₒF ₁-ATP synthase). Furthermore, physiological enhancement of G0s2 expression prevented cells from ATP depletion and induced a cellular tolerance for hypoxic stress. These results show that G0s2 positively regulates OXPHOS activity by interacting with F ₒF ₁-ATP synthase, which causes an increase in ATP production in response to hypoxic stress and protects cells from a critical energy crisis. These findings contribute to the understanding of a unique stress response to energy depletion. Additionally, this study shows the importance of assessing intramitochondrial ATP levels to evaluate OXPHOS activity in living cells.