Role of autophagy and other downstream effectors in lifespan extension by teh GCN4/ATF4 pahtway

点击翻译按钮获取中文摘要

We now know multiple pathways that delay aging, and have extended the lifespan of some animals by as much as 10-fold, yet we do not fully understand the final mechanistic effectors of delayed aging in any example to date. Thus we do not know the underlying changes involved in natural aging, presumably offset or delayed by our interventions. The long-term goal is to is to understand the most downstream changes in delayed aging. This will allow a rational approach to developing interventions to broadly delay the onset of multiple human diseases of aging such as Alzheimer’s disease and cancer. The overall objective in this application, the next step in pursuit of that long-term goal, is to understand downstream effectors of delayed aging specifically in the novel Gcn4 pathway. The central hypothesis is that targets of conserved transcription factor Gcn4 are the likely effectors, that the most relevant of these will be shared by multiple distinct Gcn4-dependent interventions, and that autophagy and increased protein turnover are likely to play a key role. The rationale for the proposed research is two-fold: 1) once we know the effectors of Gcn4-mediated delayed aging, they can be directly manipulated, giving approaches for prevention and treatment of human diseases of aging; 2) A functionally validated set of effectors allows us to ask if these are shared by other pathways, and will also shed light on the changes that underly natural aging. Guided by our preliminary data, this will be tested by pursuing three specific aims: 1) Determine the Gcn4-dependence of mitochondrial translational deletions; 2) Determine the role of autophagy in Gcn4-mediated delayed aging; and 3) Identify and validate the most functionally relevant transcriptional targets of Gcn4 / ATF-5. In part of the second aim we will use the UNM AIM CoBRE Core Amnis Imagestream to simultaneously measure the age, autophagy level, and Gcn4 protein level of thousands of yeast. The approach is innovative, in the applicant’s opinion, because it represents a new and substantive departure from the status quo byassaying transcriptional output following multiple distinct interventions dependent on the same transcription factor, using a novel block design RNAseq-ANOVA model of changes in transcript levels, in order to focus specifically on those transcriptional changes tied to our phenotype of delayed aging while excluding others. It also uses validation through lifespan measurements experiments in two distantly related model organisms, to ask which changes are most conserved, and thus most likely to be relevant to human biology. The proposed research is significant, because a fuller understanding of the downstream effectors of delayed aging will identify drug targets with translational importance in the prevention and treatment of multiple human diseases of aging. The potential impact of these findings is underscored by the fact that we cannot now preclude the possibility that multiple known pathways that delay aging, such as caloric restriction, Insulin / IGF1 signaling, and TOR, all effect their phenotype largely through changes in autophagy, nor can we rule out that all of these pathways do this in some part by converging on Gcn4.