Nanoelectrode arrays for study of the molecular mechanisms, triggers, and inhibit

描述(申请人提供)：线粒体是细胞凋亡的中心调节器，这一过程由线粒体通透性转换孔(MtPTP)激活启动，mtPTP是几种线粒体蛋白质的聚合体。当这个孔打开时，线粒体内膜的临界膜极化消失，离子在基质和胞浆之间平衡，导致线粒体肿胀。这导致线粒体膜间间隙的内容释放到细胞胞浆中，包括一些促进细胞死亡的因子杀死细胞。线粒体PTP可通过摄取过量的钙离子、增加氧化应激、降低线粒体膜电位、降低ADP和ATP来激活。人们普遍认为，抑制细胞凋亡是肿瘤发生的基本步骤之一。癌细胞对促进凋亡的信号没有反应，因此能够不受控制地增殖。因此，诱导细胞凋亡是化疗化合物的作用方式之一。为了进一步高通量研究细胞凋亡的生化促进剂和抑制物，并确定单个线粒体膜电位P的变化是否对细胞代谢重要，我们需要开发一个系统来监测单个线粒体中的P。为了实现这一目标，我们建议扩展使用线粒体附着的平行电极阵列来监测神经元动作电位的研究。我们的论文是开发一种纳米电极技术，可以在不实际穿透膜的情况下，通过线粒体内膜磷脂双层电容式测量膜电位。我们建议开发具有足够高空间和时间分辨率的纳米电传感器阵列，以监测线粒体大小的脂泡和单个有丝分裂体表面的电荷变化。利用这项技术，我们将询问正常细胞和癌细胞中P的调节。目前认为线粒体代谢的几个关键特征对癌细胞线粒体功能的改变很重要：Akt信号转导通路的改变，己糖激酶II的诱导，腺核苷酸转运体(ANT)亚型表达的改变，SOC2细胞色素c氧化酶(Complex IV，COX)组装因子的下调，线粒体DNA(MtDNA)基因的突变，以及线粒体通透性转换孔(MtPTP)的调节及其与促凋亡和抗凋亡的bcl2家族蛋白的相互作用。虽然所有这些都是癌细胞代谢变化的重要因素，但它们仍然不能解释在癌细胞中观察到的线粒体功能几乎普遍的变化。监测线粒体中磷的高通量技术将使癌症生物学中对这些问题的进一步研究成为可能。

DESCRIPTION (provided by applicant): Mitochondria are the central regulator of apoptosis, a process initiated by the activation of the mitochondrial permeability transition pore (mtPTP), an aggregate of several mitochondrial proteins. When this pore opens, the critical membrane polarization of the mitochondrial inner membrane disappears and ions equilibrate between the matrix and cytosol resulting in mitochondrial swelling. This leads to release of the contents of the mitochondrial intermembrane space into the cell cytosol, including a number of cell death promoting factors killing the cell. The mtPTP can be activated by uptake of excessive Ca++; increased oxidative stress; decreased mitochondrial membrane potential, and reduced ADP and ATP. It is generally agreed upon that repression of apoptosis is one of the fundamental steps in tumorigenesis. Cancer cells acquire unresponsiveness to apoptosis facilitating signals, thus enabling uncontrolled proliferation. For this reason, the induction of apoptosis is one of the modes of actions of chemotherapeutic compounds. In order to allow further high throughput studies of the biochemical facilitators and inhibitors, of apoptosis, and to determine if changes in individual mitochondrial membrane potential P are important to cellular metabolism, we need to develop a system to monitor P in individual mitochondria. To accomplish this objective, we propose to extend studies that have monitored the action potentials in neurons using an array of parallel electrodes to which the mitochondria are adhered. Our thesis is that a nanoelectrode technology can be developed to capacitively measure membrane potential across the mitochondrial inner membrane phospholipid bilayer without actually penetrating the membrane. We propose to develop nano-electrical transduction sensor arrays with sufficiently high spatial and temporal resolution to monitor the charge changes on the surface of a mitochondrion sized lipid vesicle and the individual mitoplast. With this technology, we will then interrogate the regulation of P in normal and cancer cells. Several key features on mitochondrial metabolism are now recognized as important to the alteration of cancer cell mitochondrial function: changes in the Akt signal transduction pathway, induction of hexokinase II, alteration an adenine nucleotide translocator (ANT) isoform expression, down regulation of the SOC2 cytochrome c oxidase (complex IV, COX) assembly factor, mutation in mitochondrial DNA (mtDNA) genes, and modulation of the mitochondrial permeability transition pore (mtPTP) and its interaction with the pro- and anti- apoptotic Bcl2 family proteins. While all of these are important factors in the alteration of cancer cell metabolism, they still fall short of explaining the near universal alterations in mitochondrial function observed in cancer cells. A high throughput technology to monitor P in mitochondria will allow further studies of these issues in cancer biology.