PS1功能缺失对线粒体凋亡通路和内质网应激相互作用的影响

发布时间：2018-04-17 04:02

本文选题：AD + PS1　；参考：《华东师范大学》2016年硕士论文

【摘要】：阿尔兹海默症(Alzheimer disease, AD)是临床上常见的神经退行性疾病之一,认知能力的逐步丧失是其主要的临床特征,且伴随大脑中神经元胞外神经炎斑块Ap的大量累积和Tau蛋白的过度磷酸化导致的神经元纤维缠结,这些病理学变化被认为是大脑神经细胞大量凋亡及发生认知障碍的主要原因。近年来研究显示神经元凋亡还与线粒体和内质网功能异常有关。我们前期在PS1/PS2条件性双敲(PS1/2 conditional double knock out, PS1/2cDKO)小鼠大脑中发现神经元线粒体出现功能和形态异常；在PS1干扰(即PS功能缺失)的SH-SY5Y细胞模型上,我们则发现PS1功能缺失诱导的神经元凋亡受线粒体PS1-PARL-OPA1信号途径调控,即在PS1瞬时干扰细胞模型中过表达PARL后,下降的OPA1便上调到正常水平,凋亡现象出现减弱。本研究中,我们进一步发现PS1/2 cDKO小鼠大脑抗凋亡蛋白PARL与其调控的线粒体融合蛋白OPA1在RNA水平和蛋白水平均表达下调,与PS1干扰的SH-SY5Y细胞模型上观察到的研究结果一致。本研究围绕线粒体PS1-PARL-OPA1凋亡途径,发现在PS1瞬时干扰细胞模型中过表达OPA1后并不改变PS1和PARL的低表达,凋亡现象未出现显著的改变,说明OPA1虽过表达但缺少PARL对其的剪切,仍无法行使其正常生理功能。线粒体和内质网(Endoplasmic Reticulum, ER)作为两个独立的细胞器,虽有不同的分工但在细胞稳态和生理功能的调节上紧密相关。PS1除了影响线粒体的结构和功能,也参与内质网的功能调节。我们前期也发现在PS1干扰的SH-SY5Y细胞模型上PS1缺失能够引起内质网应激,虽然应激的强度较弱。然而,在PS1缺失情况下,我们对线粒体与内质网之间存在怎样的作用关系,以及这种相互作用对细胞命运的影响并未了解很多。本研究发现PS1缺失引起的轻微内质网应激对线粒体PARL-OPA1凋亡通路并不产生显著影响,可当我们使用内质网应激诱导剂在PS1干扰的SH-SY5Y细胞模型上诱导内质网轻度应激时,线粒体PArL表达水平升高,线粒体内细胞色素C (Cytochrome C)表达上升,但是在正常细胞上诱导轻度内质网应激并没有检测出两种蛋白的上调,这提示我们,轻度内质网应激可能激活了内质网调控细胞平衡的保护机制,使细胞更趋向于存活方向,由此抵消了PSl功能缺失所诱导的线粒体PARL-OPA1凋亡通路；同时,我们还发现这种保护作用不仅与内质网的应激程度有关,可能还具有PS1缺失的依赖性。因此,内质网应激与线粒体之间相互作用的适度调节可能会成为抑制神经细胞PS-PARL-OPA1凋亡通路激活的新途径。在今后的研究中,不仅需要在PS 1/2 cDKO小、鼠上进一步验证细胞模型上的结果,还需要深入探究“PS功能缺失”情况下线粒体与内质网的相互作用的确切分子调控机制。
[Abstract]:Alzheimer disease (ADD) is one of the most common neurodegenerative diseases.The neuronal fibrillary tangles caused by the accumulation of AP and the excessive phosphorylation of Tau protein were associated with the neuronal extracellular neuritis plaques in the brain. These pathological changes were considered to be the main reasons for the large number of apoptosis and cognitive impairment of neurocytes in the brain.Recent studies have shown that neuronal apoptosis is also associated with mitochondrial and endoplasmic reticulum dysfunction.We found functional and morphological abnormalities of neuronal mitochondria in the brain of PS1/PS2 conditioned double knockout PS1 / 2 conditional double knock out2 (PS1 / 2cDKO) mice, and in the SH-SY5Y cell model with PS1 interference (PS absence).We found that neuronal apoptosis induced by loss of PS1 function was regulated by mitochondrial PS1-PARL-OPA1 signaling pathway, that is, after over-expression of PARL in PS1 transient interference cell model, decreased OPA1 was up-regulated to normal level, and apoptosis was weakened.In this study, we further found that the expression of anti-apoptotic protein PARL and its regulated mitochondrial fusion protein OPA1 in PS1/2 cDKO mice were down-regulated at both RNA and protein levels, which was consistent with the results observed on SH-SY5Y cell model interfered with PS1.This study focused on the mitochondrial PS1-PARL-OPA1 apoptosis pathway. It was found that the overexpression of OPA1 did not change the low expression of PS1 and PARL after overexpression of OPA1 in the PS1 cell model, and the phenomenon of apoptosis did not change significantly, indicating that OPA1 was overexpressed but not shearing by PARL.Still unable to exercise its normal physiological function.As two independent organelles, mitochondria and endoplasmic reticulum Endoplasmic Reticulum.PS1 is closely related to the regulation of cellular homeostasis and physiological function. PS1 not only affects the structure and function of mitochondria, but also participates in the regulation of endoplasmic reticulum function.We also found that PS1 deletion induced endoplasmic reticulum stress in SH-SY5Y cell models with PS1 interference, although the stress intensity was weak.However, in the absence of PS1, we do not know much about the relationship between mitochondria and endoplasmic reticulum and the effect of this interaction on the fate of cells.In this study, we found that mild endoplasmic reticulum stress induced by PS1 deletion had no significant effect on mitochondrial PARL-OPA1 apoptosis pathway, but when we used endoplasmic reticulum stress inducer to induce mild endoplasmic reticulum stress on SH-SY5Y cell model with PS1 interference,Mitochondrial PArL expression increased, cytochrome C (cytochrome C) expression increased in mitochondria, but mild endoplasmic reticulum stress induced by mild endoplasmic reticulum stress in normal cells did not detect the up-regulation of two proteins.Mild endoplasmic reticulum stress may activate the protective mechanism of endoplasmic reticulum (ER) regulation of cell balance and make cells more likely to survive, thus counteracting the mitochondrial PARL-OPA1 apoptosis pathway induced by PSl dysfunction.We also found that this protective effect is not only related to the stress of endoplasmic reticulum, but also may be dependent on PS1 deletion.Therefore, the moderate regulation of the interaction between endoplasmic reticulum stress and mitochondria may be a new way to inhibit the activation of neuronal PS-PARL-OPA1 apoptosis pathway.In future studies, we need not only to further verify the results of the cell model in PS 1 / 2 cDKO mice, but also to explore the exact molecular regulation mechanism of the interaction between mitochondria and endoplasmic reticulum in the case of "PS functional deficiency".
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：R749.16

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