Cyclic AMP Produced inside Mitochondria Regulates Oxidative Phosphorylation

• Published in: Cell metabolism Vol. 9; no. 3; pp. 265 - 276
• Main Authors: Acin-Perez, Rebeca, Salazar, Eric, Kamenetsky, Margarita, Buck, Jochen, Levin, Lonny R., Manfredi, Giovanni
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2009
• Subjects: Adenylyl Cyclases - genetics; Adenylyl Cyclases - metabolism; Animals; Carbon Dioxide - metabolism; Cyclic AMP - metabolism; Cyclic AMP-Dependent Protein Kinases - metabolism; HeLa Cells; Humans; Membrane Potential, Mitochondrial - physiology; Mice; Mice, Transgenic; Mitochondria - metabolism; Mitochondrial Proteins - metabolism; Oxidation-Reduction; Oxidative Phosphorylation; Reactive Oxygen Species - metabolism; Signal Transduction - physiology
• ISSN: 1550-4131; 1932-7420
• DOI: 10.1016/j.cmet.2009.01.012

Mitochondria constantly respond to changes in substrate availability and energy utilization to maintain cellular ATP supplies, and at the same time control reactive oxygen radical (ROS) production. Reversible phosphorylation of mitochondrial proteins has been proposed to play a fundamental role in metabolic homeostasis, but very little is known about the signaling pathways involved. We show here that protein kinase A (PKA) regulates ATP production by phosphorylation of mitochondrial proteins, including subunits of cytochrome c oxidase. The cyclic AMP (cAMP), which activates mitochondrial PKA, does not originate from cytoplasmic sources but is generated within mitochondria by the carbon dioxide/bicarbonate-regulated soluble adenylyl cyclase (sAC) in response to metabolically generated carbon dioxide. We demonstrate for the first time the existence of a CO 2-HCO 3 −-sAC-cAMP-PKA (mito-sAC) signaling cascade wholly contained within mitochondria, which serves as a metabolic sensor modulating ATP generation and ROS production in response to nutrient availability.