Resetting Skeletal Circadian Clocks: The Role of Mechanical Loading and Hyperosmolarity
Mechanical loading and hyperosmolarity, associated with daily rest/activity patterns and changes in osmotic pressure, respectively, have been found to reset circadian clocks in skeletal tissues such as cartilage and intervertebral discs. The study showed that mechanical loading during the resting phase and hyperosmotic challenge can synchronize and enhance the circadian rhythms of these tissues. The response to hyperosmolarity was found to be cell-type specific, with chondrocytes and annulus fibrosus cells showing increased clock amplitudes, while osteosarcoma cells and keratinocytes exhibited disrupted circadian oscillation. These findings provide insights into the mechanisms by which skeletal clocks are entrained and suggest potential therapeutic targets for age-related tissue degeneration.