Circadian regulation in aging: Implications for spaceflight and life on earth

Abstract

Alterations in the circadian system are characteristic of aging on Earth. With the decline in physiological processes due to aging, several health concerns including vision loss, cardiovascular disorders, cognitive impairments, and muscle mass loss arise in elderly populations. Similar health risks are reported as “red flag” risks among astronauts during and after a long‐term Space exploration journey. However, little is known about the common molecular alterations underlying terrestrial aging and space‐related aging in astronauts, and controversial conclusions have been recently reported. In light of the regulatory role of the circadian clock in the maintenance of human health, we review here the overlapping role of the circadian clock both on aging on Earth and spaceflight with a focus on the four most affected systems: visual, cardiovascular, central nervous, and musculoskeletal systems. In this review, we briefly introduce the regulatory role of the circadian clock in specific cellular processes followed by alterations in those processes due to aging. We next summarize the known molecular alterations associated with spaceflight, highlighting involved clock‐regulated genes in space flown Drosophila, nematodes, small mammals, and astronauts. Finally, we discuss common genes that are altered in terms of their expression due to aging on Earth and spaceflight. Altogether, the data elaborated in this review strengthen our hypothesis regarding the timely need to include circadian dysregulation as an emerging hallmark of aging on Earth and beyond.

“Time Is out of Joint” in Pluripotent Stem Cells: How and Why

“…Among the many physiological alterations occurring during aging, the exhaustion of the adult stem cell reservoir and dysregulation of circadian rhythms are emerging [132][133][134]. Prospectively, deepening the currently appearing complex interplay between the cellular biology of stem cells and rhythmic time-keeping mechanisms may offer new opportunities for healthy and longer life.…”

Sex and age-dependent characterization of the circadian clock as a potential biomarker for physical performance: A prospective study protocol

“…Females tend to exhibit an earlier circadian peak phase as compared to males, and previous reports showed a different therapeutic impact among females and males in colorectal cancer patients treated under chrono-modulated therapy regimes [17,18]. Aging may also influence the CR resulting in dampening of the circadian amplitude, an advance of circadian phase, or result in gain or loss of rhythmic circadian expression [19][20][21][22][23][24]. Recent transcriptomics studies further revealed differential regulation of circadian gene expression between middle/older aged individuals, and younger adults [23,25].…”