Browsing by Author "Lin, Ming-Yi"

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    Oxidative stress promotes autophagic cell death in human neuroblastoma cells with ectopic transfer of mitochondrial PPP2R2B (Bβ2)
    (2009-12-18) Cheng, Wan-Ting; Guo, Zhi-Xuan; Lin, Chia-An; Lin, Ming-Yi; Tung, Li-Chu; Fang, Kang
    Abstract Background The multifunctional protein phosphatase 2A (PP2A) is a heterotrimeric serine/threonine protein phosphatase composed of a scaffolding, catalytic and regulatory subunits. By modifying various downstream signal transducers, the aberrant expression of the brain-targeted regulatory subunit PPP2R2B is associated with the onset of a panel of neuronal disorders. The alternatively splicing of PPP2R2B encodes two regulatory subunit isoforms that determine cellular distribution of the neuron-specific holoenzyme to mitochondria (Bβ2) and cytoplasm (Bβ1), respectively. Results Human neuroblastoma cells were transfected with PPP2R2B constructs encoding the complete sequences of Bβ2 and Bβ1, respectively. The colonies with antibiotic resistance were selected as stable cell lines. Both ectopic Bβ1 and Bβ2 clones exhibited characteristics of autophagy. To test how cells respond to reactive oxygen species generators, the cells were treated with either hydrogen peroxide or t-butyl hydroperoxide and Bβ2 clones induced cell death. Suppression of autophagy using either RNA interference of the essential autophagy gene or pharmacological inhibitor rescued cell death caused by oxidative stress. Conclusions Cells with ectopically expressed mitochondria-targeted regulatory subunit PPP2R2B of the holoenzyme PP2A were shown predisposed to autophagy and oxidative stress induced cell death that is related to apoptosis. The results promised a model for studying the mechanism and function of aberrant PPP2R2B expression in neuronal cells. The work provided a new target for understanding and prevention of neuropathogenesis.
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    紅外線明亮星系的活躍星系核特性
    (2013) 林明儀; Lin, Ming-Yi
    為了了解活躍星系核活動與恆星形成在星系演化中的相互影響，我們研究142個星系樣品，來自宇宙演化勘測視野(Cosmic Evolution Survey field)，並且擁有X-ray與遠紅外線70μm觀測資料。我們的資料來自已公開之網路資料庫，X-ray來自錢德拉太空望遠鏡(Chandra)與XMM-牛頓太空望遠鏡(XMM-Newton); 遠紅外線70μm的資料則來自史匹哲太空望遠鏡(Spitzer)之多波段成像光度計(MIPS)觀測。儘管近紅外光測指數(color indexes)指出有恆星形成的存在，2-10 keV與全波段紅外光線(total infrared luminosity)的比值顯示，當固定全波段紅外光線能量時，2-10 keV的能量高出許多，暗示活躍星系核活動可能大於恆星形成活動。我們利用X-ray的硬指數(Hardness ratio)來當作”掩蔽活躍星系核”之指示標準，我們發現我們特殊的樣品選擇相對於單一X-ray的星系選擇有多餘的硬指數高值，可能與不同物理尺度的雲氣與灰塵有關。我們同時發現我們的樣品之冷灰塵溫度並不受X-ray有無的影響，灰塵溫度與活躍星系核活動之間可能沒有直接的關連。