Formation of ion chyannels by amyloidogenic proteins and screening for protective substances

阿尔茨海默病β-淀粉样蛋白（a - β p）的构象改变增强了其神经毒性，最终导致阿尔茨海默病的发病。最近的研究表明，一个共同的机制是基于被称为“构象疾病”的多种疾病，包括其他神经退行性疾病，如朊病毒疾病、帕金森病和亨廷顿病。这些疾病在朊蛋白、a-synuclein、聚谷氨酰胺等疾病相关蛋白形成含有淀粉样蛋白原纤维的β-薄片和引入凋亡变性方面具有相似性。虽然这些构象疾病相关蛋白诱导神经退行性变的分子机制尚不清楚，但这些蛋白具有直接结合到膜上并形成钙透性离子通道的能力。在本研究中，我们利用Ca成像系统研究了淀粉样蛋白形成通道的详细特征，包括β -淀粉样蛋白、朊蛋白片段肽、α -突触核蛋白片段肽。我们发现这些蛋白导致细胞内钙水平的快速增加。由d -氨基酸残基组成的淀粉样肽也引起类似的钙增加。没有已知的递质抑制剂或通道阻滞剂能抑制钙离子的变化。因此，我们得出结论，这些淀粉样蛋白肽引起的Ca增加是基于“淀粉样蛋白通道”。此外，我们寻找防止淀粉样蛋白诱导的Ca增加的物质，以筛选这些神经退行性疾病的可能治疗方法。几种神经类固醇明显抑制钙的增加。此外，我们还研究了微量金属对淀粉样蛋白构象变化的影响。

The conformational changes of Alzheimer's β-amyloid protein (AβP) enhance its neurotoxicity, and finally lead to Alzheimer's pathogenesis. Recent studies have suggested that a common mechanism is based on the diverse diseases termed "conformational diseases" including other neurodegenerative diseases such as prion diseases, Parkinson's disease, and Huntington's disease. These diseases share similarity in the formation of β-sheet containing amyloid fibrils by disease-related proteins such including prion protein, a-synuclein, polyglutamine and the introduction of apoptotic degeneration. Although the molecular mechanism of neurodegeneration induced by these conformational disease-related proteins remains elusive, these proteins have the ability to directly incorporate into membranes and to form calcium-permeable ion channels. In this research, we have investigated the detailed characteristics of channel formation by amyloidogenic proteins including beta-amyloid protein, prion protein fragment peptides, alpha-synuclein fragment peptides using Ca imaging system. We found that these proteins cause rapid increase of intracellular Ca levels. Amyloid peptides composed by D-amino acid residues also cause similar Ca increase. No known transmitter inhibitors or channel blockers inhibit the Ca changes. Therefore, we conclude that Ca increase caused by these amyloidogenic peptides are based on the "amyloid channels". Furthermore, we searched substances which prevent Ca increase induced by amyloid proteins for the aim of screening possible treatment for theses neurodegenerative diseases. Several neurosteroids marked inhibit the Ca increase. Moreover, we investigated the effects of trace metals which effect the conformational changes of amyloidogenic proteins.