Basic Research Division, Department of Medical Research, Microscopy Service Laboratory, Taipei Veterans General Hospital, Taipei, Taiwan, ROC.
Institute of Biophotonics, School of Medical Technology and Engineering, National Yang-Ming University, Taipei, Taiwan, ROC.
J Chin Med Assoc. 2020 Apr;83(4):357-366. doi: 10.1097/JCMA.0000000000000280.
Nitric oxide (NO), which possesses both protective and toxic properties, has been observed to have a complicated biphasic character within various types of tissues, including neuronal cells. NO was also found to cause the increase of another important signaling molecular Zn (termed as NZR). The molecular mechanism of NZR has been extensively investigated, but the source of Zn is present of a major candidate that is yet to be answered. The NO-protein kinase G (PKG) pathway, mitochondria, and metallothioneins (MTs), are all proposed to be the individual source of NZR. However, this hypothesis remains inconclusive. In this study, we examined the function of PKG signaling cascades, the mitochondria storage, and MT-1 during NZR of living PC12 cells.
We applied live-cell imaging in combination with pharmacological inhibitors and activators as well as in vitro Zn assay to dissect the functions of the above candidates in NZR.
Two mechanisms, namely, mitochondria as the only Zn source and the opening of NO-PKG-dependent mitochondrial ATP-sensitive potassium channels (mKATP) as the key to releasing NO-induced increase in mitochondrial Zn, were proven to be the two critical paths of NZR in neuronal-related cells.
This new finding provides a reasonable explanation to previously existing and contradictory conclusions regarding the function of mitochondria/mKATP and PKG signaling on the molecular mechanism of NZR.
一氧化氮（NO）具有保护和毒性双重特性，在包括神经元细胞在内的各种组织中表现出复杂的双相特征。NO 还被发现会导致另一种重要信号分子 Zn（称为 NZR）的增加。NZR 的分子机制已得到广泛研究，但 Zn 的来源是一个尚未得到解答的主要候选者。NO-蛋白激酶 G（PKG）途径、线粒体和金属硫蛋白（MTs）都被认为是 NZR 的单独来源。然而，这一假说仍存在争议。在这项研究中，我们研究了 PKG 信号级联、线粒体储存和 MT-1 在活 PC12 细胞中 NZR 过程中的功能。
我们应用活细胞成像技术，结合药理学抑制剂和激活剂以及体外 Zn 测定法，来剖析上述候选物在 NZR 中的作用。
证明了两种机制，即线粒体是唯一的 Zn 来源，以及 NO-PKG 依赖性线粒体 ATP 敏感性钾通道（mKATP）的开放是释放 NO 诱导的线粒体 Zn 增加的关键，这两种机制是神经元相关细胞中 NZR 的两个关键途径。
这一新发现为先前存在的关于线粒体/mKATP 和 PKG 信号在 NZR 分子机制上的功能的相互矛盾的结论提供了合理的解释。
