Sex-dimorphic and age-dependent organization of 24 hour gene expression rhythms in human

Abstract

The circadian clock modulates most of human physiology. However, the organization of tissue-specific gene expression rhythms is still poorly known, as well as age and sex dependencies. We leveraged the Genotype-Tissue Expression project (GTEx) using a novel algorithm to assign a unique circadian phase to 914 individuals and transfer time information from stronger to weaker clocks. These donor internal phases allowed us to identify and compare programs of rhythmic gene expression in 46 tissues. Clock transcripts showed highly conserved phase and amplitude relationships across tissues, and were tightly synchronized across the body. Tissue rhythmic gene expression programs differed in breadth, covering global and tissue-specific functions, including metabolic pathways and systemic responses such as heat shock. The circadian clock structure and amplitude was indistinguishable across sexes and age groups. However, overall gene expression rhythms were highly sex-dimorphic and more sustained in females. Moreover, rhythmic programs dampened with age across the body. Together, our stratified analysis unveiled a rich organization of sex- and age-specific circadian gene expression rhythms in humans. One sentence summaryCircadian phase inference of 914 GTEx donors reveals sex- and age-dependent rhythmic gene expression programs across 46 human tissues.