Investigating the relationship between mitochondrial dysfunction and apoptosis, autophagy and cellular senescence

除了产生能量外，线粒体在细胞凋亡、自噬和衰老中起着至关重要的作用。氧化还原信号、自噬、衰老和线粒体功能障碍之间的关系/串扰尚不清楚。据推测，有毒蛋白质（氧化或亚硝基化）的积累和线粒体的故障导致进一步的氧化应激，可能导致上述任何现象。自噬是对这种应激的反应，以消除功能失调的蛋白质和细胞器。然而，如果自噬被抑制，细胞死亡（在神经元系统中）或衰老（在成纤维细胞中）被激活。以野生型和早老素-1突变的正常人成纤维细胞为模型，研究细胞开关触发衰老、凋亡和自噬的机制以及线粒体在这些过程中的作用。***与本项目相关，我们建立了具有野生型早老素-1 （PS-1）和具有突变型PS-1的原代人皮肤成纤维细胞（NHFs）的优良细胞模型，用于研究这三种现象1。我们已经确定，PS-1突变的NHFs具有：a)活性氧（ROS）的产生增加；b) MnSOD、p21、p16、Rb表达上调，导致早衰，增殖细胞核抗原（PCNA）表达下调；C)自噬水平降低；D)抵抗外部氧化应激引起的细胞凋亡。此外，我们发现水溶性辅酶q10 （WS CoQ10）抑制PS-1突变细胞的过早衰老，并导致这些细胞恢复自噬1。然而，由于PS-1突变导致的线粒体功能的确切缺陷仍不清楚，诱导衰老或自噬的生化开关以响应ROS的增加仍不清楚。WS CoQ10如何恢复PS-1突变成纤维细胞的自噬诱导仍然是一个非常重要和有趣的问题，尚未得到回答。为了解决上述知识缺口，本项目提出以下研究目标：***1)PS-1突变成纤维细胞（PSMF）线粒体功能障碍的研究。表征信号级联从线粒体氧化应激到衰老，自噬，或凋亡。***本项目的成功完成将使我们进一步了解衰老、自噬和凋亡的机制以及这些基本细胞过程之间的复杂关系。**

In addition to energy production, the mitochondria play a crucial role in apoptosis, autophagy and senescence. The relationship/crosstalk between redox signaling, autophagy, senescence and mitochondrial dysfunction is not well understood. It is hypothesized that accumulation of toxic proteins (oxidized or nitrosylated) and malfunctioning of mitochondrion lead to further oxidative stress that could lead to any of the aforementioned phenomena. Autophagy is induced in response to such stress in order to eliminate dysfunctional proteins and organelles. However, if autophagy is inhibited, cell death (in the neuronal system) or senescence (in fibroblasts) is activated. Using normal human fibroblasts with wild type and Presenilin-1 mutations as models, the research program is set to investigate the mechanism of cellular switches that trigger senescence, apoptosis and autophagy and role of mitochondria in these processes.***Relevant to the proposed program, we have developed an excellent cellular model of primary human skin fibroblasts (NHFs) with wild type presenilin-1 (PS-1) and those with mutated PS-1 for the study of the three phenomenons1. We have established that the NHFs with PS-1 mutation have: a) increased production of reactive oxygen species (ROS); b) upregulation of MnSOD, p21, p16, and Rb, leading to premature senescence and downregulation of proliferating cell nuclear antigen (PCNA); c) decreased levels of autophagy; d) resistance to apoptosis caused by external oxidative stress. Furthermore, we discovered that water-soluble CoQ10 (WS CoQ10) inhibits premature senescence in PS-1 mutant cells and causes resumption of autophagy in these cells1. However, the exact deficiency in the mitochondrial function due to the PS-1 mutation is still not understood, the biochemical switch for the induction of either senescence or autophagy in response to increased generation of ROS remains unknown. How does WS CoQ10 restore autophagic induction in PS-1 mutated fibroblasts remains a very important and interesting question, yet to be answered. In order to address the aforementioned knowledge gap, this program proposes the following research aims: ***1) Investigation of mitochondrial dysfunction in PS-1 mutated fibroblasts (PSMF).***2. Characterization of signalling cascades from mitochondrial oxidative stress to senescence, autophagy, or apoptosis.***Successful completion of this program will lead to our advancement of understanding of the mechanism of senescence, autophagy, and apoptosis and the intricate relationship between these fundamental cellular processes.  **