MicroRNA mediators of stress, dietary restriction and aging

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DESCRIPTION (provided by applicant): Aging and stress responses are tightly linked~ indeed, most interventions that extend lifespan appear to do so at least in part through potentiation of stress responses. Nevertheless, the genetic and mechanistic basis of this central relationship remains poorly understood. Here we will test the hypothesis that microRNAs (miRNAs) coordinate stress-responsive pathways in response to lifespan-prolonging interventions. We propose the following: To identify critical new miRNAs that link stress responses to aging in C. elegans, we profiled expression of small RNAs during development, aging and in stressed conditions (heat shock, starvation, hypoxia and oxidative stress). Since miRNAs that are differentially regulated during stress are likely to be mechanistic regulators of the stress response, we propose to characterize ten of the most differentially expressed miRNAs and determine their position in the gene-regulatory architecture of stress responses. We will also integrate our previous profiling and functional analyses of aging-associated miRNAs with these results to identify miRNAs that are associated with both stress and aging and test whether these genes provide mechanistic links between these conditions. To investigate "network-level" roles of microRNAs in regulation of stress and aging, we propose to elucidate the underlying regulatory network of genes and miRNAs involved in aging and stress. In order to identify critical new sets of miRNAs and pathways that link these processes, we have integrated transcription-factor binding site information, with miRNA target predictions to build a preliminary interaction network of the known regulatory relationships between transcription factors, aging- associated miRNAs, and miRNA biogenesis genes. We also propose to determine targets of key miRNAs biochemically via CLIP-seq and RNA-seq in the presence and absence of the miRNA. These data will allow us to improve the known miRNA-mRNA regulatory interaction network. Then, using this network, we will find miRNAs that comprise feedback loops and highly connected interaction nodes. We will test whether these highly connected miRNAs play critical roles in aging, stress responses, or in integrating the two. To identify miRNA mediators of lifespan extension due to dietary restriction. Our preliminary data point to miR-71 and miR-228 as key network nodes connected to pha-4 and skn-1, transcription factors critical for the response to dietary restriction and other stressors. We will characterize the roles of thes miRNAs and use our gene- regulatory network to identify other such candidate miRNAs. We also propose to identify miRNAs differentially expressed in dietary restriction via deep sequencing and include these in our network analysis above. We are uniquely well situated to carry out this work, as the Slack lab combines extensive experience in miRNAs and aging biology with leading expertise in genome-wide small-RNA characterization. MiRNA analogues and antagonists are pharmacologically tractable~ thus identifying critical aging and stress responsive miRNAs in C. elegans may lead directly to lifespan and healthspan-prolonging interventions in humans.