Modulation of Oxidative phosphorylation by mitochondrial soluble adenylyl cyclase

总的来说，线粒体疾病是最常见的遗传性疾病之一。 疾病它们可以由核或线粒体（mtDNA）基因突变引起， 编码氧化磷酸化（OXPHOS）机制的组成部分。是 很明显，线粒体必须不断适应底物可用性的变化， 通过调节OXPHOS以维持细胞ATP供应来利用能量。然而，在这方面， 关于具有线粒体遗传缺陷的细胞如何调节OXPHOS或 他们如何试图弥补自己的生化缺陷。短期OXPHOS 通过线粒体酶的可逆磷酸化调节。一 线粒体cAMP-蛋白激酶A（cAMP-PKA）途径已被假设，但 线粒体中cAMP的来源仍然难以捉摸。我们最近发现， 线粒体cAMP库由可溶性腺苷酸环化酶（sAC）产生， 对代谢产生的二氧化碳的反应。这种新型的CO2-sAC-cAMP-PKA信号转导 级联完全包含在线粒体内，并作为代谢传感器工作 调节ATP的产生以响应养分的可用性。我们发现 OXPHOS缺陷细胞对sAC-cAMP-PKA途径的调节与 与野生型细胞相比，这表明该途径可能参与了适应性 对OXPHOS缺陷的响应。因此，这一途径可能成为一个新的目标， 线粒体疾病的治疗干预。为了验证这些假设，我们提出 寻找CO2-sAC-cAMP-PKA信号通路的特异性蛋白靶点， 线粒体专注于克雷布斯循环和电子传递链的酶。 然后，一旦这些目标被确定，我们将评估蛋白质的差异， 野生型和突变型细胞之间的磷酸化。该应用程序的目标是：1） 鉴定涉及OXPHOS调节的sAC-cAMP-PKA靶点和2） 研究OXPHOS调控的分子机制， 线粒体sAC-cAMP-PKA途径。

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.