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Updated: May 10, 2026
06:53
Parallel Measurement of Circadian Clock Gene Expression and Hormone Secretion in Human Primary Cell Cultures
Published on: November 11, 2016
Comparative circadian transcriptome analysis reveals dampened and phase-advanced rhythms in sun-exposed human skin
Michael M Saint-Antoine1, Zeyad El-Houni2, Victoria L Newton3
1Chronobiology and Sleep Institute, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Journal of Investigative Dermatology
|May 8, 2026
Summary
Chronic sun exposure disrupts daily molecular rhythms in human skin, altering gene expression patterns and potentially impacting skin health. This study reveals significant differences in rhythmic gene activity between protected and sun-exposed skin.
Area of Science:
- Chronobiology
- Dermatology
- Molecular Biology
Background:
- Daily molecular rhythms influence skin functions.
- The impact of chronic sun exposure on skin's molecular rhythms is largely unknown.
- Understanding these effects is crucial for skin health and aging research.
Purpose of the Study:
- To identify and compare rhythmic genes and pathways in photoprotected versus chronically photoexposed human skin.
- To investigate how chronic UV exposure alters the circadian output in skin.
- To provide insights into the molecular mechanisms underlying sun-induced skin changes.
Main Methods:
- Collected skin biopsies from photoprotected and photoexposed sites of 20 subjects at four time points over 24 hours.
- Utilized RNA sequencing to quantify gene expression.
- Applied Cosinor analysis to identify cycling genes, their amplitudes, and peak times.
Main Results:
- Fewer genes exhibited cycling in photoexposed skin compared to photoprotected skin.
- Cycling genes in photoexposed skin showed lower amplitudes and advanced peak times.
- Identified 480 genes with distinct rhythmic properties between the two skin sites.
- Enriched pathways in photoprotected skin included DNA repair and cell cycle checkpoints, while photoexposed skin showed enrichment in epithelial mesenchymal transition and apical junction pathways.
Conclusions:
- Chronic UV exposure significantly disrupts circadian output rhythms in human skin.
- These disruptions may involve reprogramming of molecular rhythms, affecting skin physiology.
- Findings suggest a link between altered skin rhythms and the detrimental effects of sun exposure.
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