As a whole, mitochondrial diseases are among the most common hereditary diseases. They can arise from mutations of nuclear or mitochondrial (mtDNA) genes that encode for components of the oxidative phosphorylation (OXPHOS) machinery. It is clear that mitochondria have to constantly adapt to changes in substrate availability and energy utilization by modulating OXPHOS to maintain cellular ATP supplies. However, very little is known on how cells with mitochondrial genetic defects regulate OXPHOS or how they attempt to compensate for their biochemical defects. Short-term OXPHOS regulation is modulated by reversible phosphorylation of mitochondrial enzymes. A mitochondrial cAMP-Protein kinase A (cAMP-PKA) pathway has been hypothesized, but the source of cAMP in mitochondria has remained elusive. We have recently found that the mitochondrial cAMP pool is generated by a soluble adenylyl cyclase (sAC) in response to metabolically generated CO2. This novel CO2-sAC-cAMP-PKA signaling cascade is entirely contained within mitochondria and operates as a metabolic sensor modulating ATP production in response to nutrients availability. We showed that OXPHOS defective cells have a different regulation of the sAC-cAMP-PKA pathway as compared to wild type cells, suggesting that the pathway may participate to the adaptive responses to OXPHOS defects. Thus, this pathway could become a novel target for therapeutic intervention in mitochondrial diseases. To test these hypotheses we propose to search for specific protein targets of the CO2-sAC-cAMP-PKA signaling pathway in mitochondria focusing on enzymes of the Krebs cycle and the electron transfer chain. Then, once these targets are identified, we will assess the differences in protein phosphorylation between wild type and mutant cells. The goals of this application are: 1) To identify sAC-cAMP-PKA targets implicated in OXPHOS regulation and 2) to investigate the molecular mechanisms underlying OXPHOS regulation by the mitochondrial sAC-cAMP-PKA pathway in OXPHOS deficient cells.

Public Health Relevance

Genetic mutations in the mitochondrial oxidative phosphorylation (OXPHOS) machinery cause metabolic diseases. How mutant cells attempt to compensate for these metabolic defects is largely unknown. Phosphorylation of mitochondrial enzymes is one mechanism of regulation of metabolic activity, and we have identified a protein phosphorylation pathway within mitochondria that may participate to the compensatory responses to OXPHOS mutations. In this project, we will investigate the mechanisms of OXPHOS regulation by this pathway in health and disease, to assess if it can become a target for therapy aimed at improving metabolic diseases. Health relevance of the proposed research (25 words) Mitochondrial disorders are severe, often fatal, metabolic diseases. The proposal will identify new targets for therapeutic intervention by exploring mechanisms whereby cells regulate mitochondrial metabolism.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM088999-01
Application #
7751683
Study Section
Special Emphasis Panel (ZRG1-GTIE-A (01))
Program Officer
Anderson, Vernon
Project Start
2009-09-01
Project End
2011-08-31
Budget Start
2009-09-01
Budget End
2010-08-31
Support Year
1
Fiscal Year
2009
Total Cost
$354,900
Indirect Cost
Name
Weill Medical College of Cornell University
Department
Neurology
Type
Schools of Medicine
DUNS #
060217502
City
New York
State
NY
Country
United States
Zip Code
10065
Chen, Qiuying; Kirk, Kathryne; Shurubor, Yevgeniya I et al. (2018) Rewiring of Glutamine Metabolism Is a Bioenergetic Adaptation of Human Cells with Mitochondrial DNA Mutations. Cell Metab 27:1007-1025.e5
Valsecchi, Federica; Konrad, Csaba; D'Aurelio, Marilena et al. (2017) Distinct intracellular sAC-cAMP domains regulate ER Ca2+ signaling and OXPHOS function. J Cell Sci 130:3713-3727
Cloonan, Suzanne M; Glass, Kimberly; Laucho-Contreras, Maria E et al. (2016) Mitochondrial iron chelation ameliorates cigarette smoke-induced bronchitis and emphysema in mice. Nat Med 22:163-74
Ramos-Espiritu, Lavoisier; Kleinboelting, Silke; Navarrete, Felipe A et al. (2016) Discovery of LRE1 as a specific and allosteric inhibitor of soluble adenylyl cyclase. Nat Chem Biol 12:838-44
Hess, Kenneth C; Liu, Jingjing; Manfredi, Giovanni et al. (2014) A mitochondrial CO2-adenylyl cyclase-cAMP signalosome controls yeast normoxic cytochrome c oxidase activity. FASEB J 28:4369-80
Valsecchi, Federica; Konrad, Csaba; Manfredi, Giovanni (2014) Role of soluble adenylyl cyclase in mitochondria. Biochim Biophys Acta 1842:2555-60
Kiss, Gergely; Konrad, Csaba; Doczi, Judit et al. (2013) The negative impact of ?-ketoglutarate dehydrogenase complex deficiency on matrix substrate-level phosphorylation. FASEB J 27:2392-406
Valsecchi, Federica; Ramos-Espiritu, Lavoisier S; Buck, Jochen et al. (2013) cAMP and mitochondria. Physiology (Bethesda) 28:199-209
Gong, Jianli; Hoyos, Beatrice; Acin-Perez, Rebeca et al. (2012) Two protein kinase C isoforms, ýý and ýý, regulate energy homeostasis in mitochondria by transmitting opposing signals to the pyruvate dehydrogenase complex. FASEB J 26:3537-49
Acin-Perez, Rebeca; Gatti, Domenico L; Bai, Yidong et al. (2011) Protein phosphorylation and prevention of cytochrome oxidase inhibition by ATP: coupled mechanisms of energy metabolism regulation. Cell Metab 13:712-9

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