Regulation of mitochondrial biogenesis by heme oxygenase-1

描述（由申请人提供）：这是一份修订申请，旨在研究催化血红素降解的诱导酶血红素加氧酶-1（HO-1）在线粒体生物合成调节中的新功能。所提出的机制是基于CO的HO（HO/CO）的内源性生产。一氧化碳，像一氧化氮（NO）一样，越来越多地被认为是一种气体信号分子，在健康和疾病中起着调节作用。我们已经发现，在生理浓度的CO上调核转录因子，核呼吸因子（NRF）-1和-2，和中央辅激活剂，PGC-11，调节，线粒体生物合成。我们的初步数据表明，CO促进线粒体DNA复制和增加线粒体DNA拷贝数在小鼠心脏线粒体生物合成。后者是在核控制下的一个重要过程，需要线粒体融合、分裂和呼吸蛋白合成，以满足器官对有氧ATP合成的持续需求，从而实现收缩功能。HO/CO促进生物合成的途径尚未明确，但我们有新的初步数据表明CO-细胞色素c氧化酶α 3-血红素在线粒体中的结合机制，导致H2 O2介导的促生存激酶，Akt/PKB和氧化还原敏感的Nrf 2转录因子的核转位的激活。我们的假设是由HO产生的生理（内源）CO通过线粒体生物发生的氧化还原活化以产生抗氧化剂和抗凋亡线粒体表型来提供细胞存活功能。我们提出了三个具体的目的：目的1：测试的假设，外源性和内源性CO激活心脏线粒体生物合成通过Akt依赖磷酸化的PGC-11。目标二：检验以下假设：HO/CO的线粒体H2 O2信号传导及其通过Nrf 2转录因子的相互作用调节HO-1和NRF-1基因表达，从而对线粒体生物发生进行转录调节。目标3：在多柔比星心肌病中，检测一氧化碳的心肌保护作用依赖于内源性HO-1活性和抗凋亡线粒体表型的产生这一假设。这些目标的完成将扩大和发展我们对CO作为线粒体健康和疾病中的细胞信号分子的作用的理解。这意味着HO/CO调节的线粒体生物合成是维持正常心血管功能以及适应氧化应激和致病性炎症的基础。这将为HO- 1的保护作用提供一种统一的机制，这种机制可能适合于通过一系列独特和新颖的策略进行治疗干预。公共卫生相关性：这是一个新的建议，以研究血红素加氧酶-1（HO-1）的一个新的功能，其中的两个主要异构体的酶，血红素转化为胆绿素，铁，和一氧化碳（CO）。我们的初步数据暗示HO-1，通过CO的生产，作为线粒体生物合成的调节剂。我们在小鼠心脏和心肌细胞中的工作表明，HO/CO调节的线粒体生物合成是适应氧化和炎症应激的基础。对我们假设的成功检验将为HO-1在健康和疾病中的多种保护作用建立统一的机制。

DESCRIPTION (provided by applicant): This is an amended application to study a novel function for the inducible enzyme that catalyzes heme degradation, heme oxygenase-1 (HO-1), in the regulation of mitochondrial biogenesis. The proposed mechanism is based on the endogenous production of CO by HO (HO/CO). CO, like nitric oxide (NO), is increasingly recognized as a gaseous signaling molecule serving regulatory roles in health and disease. We have discovered that CO at physiological concentrations up-regulates the nuclear transcription factors, nuclear respiratory factors (NRF) -1 and -2, and the central co-activator, PGC-11, which regulate , mitochondrial biogenesis. Our preliminary data show that CO promotes mtDNA replication and increases mtDNA copy number in the mouse heart during mitochondrial biogenesis. The latter is an essential process under nuclear control that requires mitochondrial fusion, fission, and respiratory protein synthesis in order to meet the organ's continuous demand for aerobic ATP synthesis for contractile function. The pathways by which HO/CO promotes biogenesis are not yet well defined but we have new preliminary data implicating CO-cytochrome c oxidase a3-heme binding in mitochondria in the mechanism, leading to H2O2-mediated activation of the pro-survival kinase, Akt/PKB and nuclear translocation of the redox-sensitive Nrf2 transcription factor. Our hypothesis is that physiological (endogenous) CO produced by HO serves a cell survival function by redox activation of mitochondrial biogenesis to produce an anti-oxidant and anti- apoptotic mitochondrial phenotype. We propose three Specific Aims: Aim 1: Test the hypothesis that exogenous and endogenous CO activates cardiac mitochondrial biogenesis through Akt-dependent phosphorylation of PGC-11. Aim 2: Test the hypothesis that mitochondrial H2O2 signaling by HO/CO and its interplay through the Nrf2 transcription factor regulate HO-1 and NRF-1 gene expression for the transcriptional regulation of mitochondrial biogenesis. Aim 3: Test the hypothesis that the myocardial protective effect of CO depends on endogenous HO-1 activity and the generation of an apoptosis-resistent mitochondrial phenotype in doxorubicin cardiomyopathy. The completion of these Aims will expand and develop our understanding of the role of CO as a cell-signaling molecule in mitochondrial health and disease. The implication is that HO/CO-regulated mitochondrial biogenesis is fundamental to the maintenance of normal cardiovascular function as well as to adaptation to oxidative stress and pathogenic inflammation. This would provide a unifying mechanism for the protective role of HO- 1 that may be amenable to therapeutic intervention by a range of unique and novel strategies. PUBLIC HEALTH RELEVANCE: This is new proposal to study a novel function for heme oxygenase-1 (HO-1), one of two main isoforms of the enzyme that converts heme into biliverdin, Fe, and carbon monoxide (CO). Our preliminary data implicate HO-1, through the production of CO, as a regulator of mitochondrial biogenesis. Our work in the mouse heart and in cardiomyocytes suggests the hypothesis that HO/CO-regulated mitochondrial biogenesis is fundamental for adaptation to oxidative and inflammatory stress. A successful test of our hypothesis would establish a unifying mechanism for the diverse protective roles of HO-1 in health and disease.