A major goal of current geroscience is to increase healthspan by preserving physiological function into older age, and as emphasized in NIA PA-17-089, there is considerable potential in using secondary analyses of existing biospecimens and data to test new hypotheses in this area. Next-generation sequencing approaches such as transcriptomics hold great promise in this context, but most sequencing data on aging are based on known proteins/genes, while the role of non-coding genetic material (the majority of the genome) is often overlooked. To address this, we used existing samples from human subjects to perform a preliminary study of total transcriptome changes with aging and exercise?one of the few proven strategies for preserving physiological function with age. We found age-related increases in gene transcription related to inflammation, a central hallmark of aging that reduces healthspan, and major changes in non-coding RNA (ncRNA). In particular, we observed: 1) an age-related increase in repetitive element (RE) transcripts, commonly overlooked ncRNA derived from repeat sequences that make up > 50% of the genome; 2) strong correlations between RE transcript levels and both inflammation and physiological function; and 3) a marked reversal of these events with exercise. These novel observations suggest that dysregulation of RE transcripts may reflect a previously unrecognized, clinically relevant mechanism of aging. Therefore, we propose to extend this preliminary study to a larger set of existing samples and data, and we hypothesize that: Aging will be associated with an increase in RE/other ncRNAs and gene expression changes consistent with hallmarks of aging (e.g., inflammation), which will be reversed with exercise. To test this, we will isolate RNA from peripheral blood cells that we have already collected from carefully matched groups (10 subjects per group) of young, older, and older exercising adults, as well as older adults who participated in an exercise intervention, and we will characterize the transcriptome by total RNA-seq. RE/other ncRNAs will be related to differences in inflammation and physiological function with aging, and may, therefore, provide insight into novel mechanisms of healthspan. We will relate RE/ncRNA and gene expression to circulating markers of inflammation and a battery of physiological function measurements (vascular, motor/physical, cognitive and metabolic) in a larger group of older adults (n = 110). Changes in RE/ncRNA/gene expression with aging and exercise may be explained by differences in chromatin structure, which could provide insight into novel targets for future studies and interventions. To test this, we will profile global chromatin accessibility in samples described above using ATAC-seq. This will be the first research of its kind to profile total transcriptome changes with aging and exercise and to relate them to inflammation and multiple domains of physiological function, and the first research of any kind to characterize genome-wide chromatin changes with aging/exercise in human subjects.
Aging leads to inflammation and physiological dysfunction that increase the risk for developing chronic disease, but exercise has the potential to prevent or delay these events. The purpose of the proposed research is to use inclusive transcriptomics (sequencing of total RNA) to characterize the effects of aging and exercise on both coding (genes) and non-coding RNAs, including repetitive sequences that are often ignored. This may provide clues to previously unrecognized causes of age-related inflammation and physiological dysfunction, as well as potential biomarkers and targets for future interventions.
