Muscle cells have their own circadian clocks, and disrupting them through shift work can have significant effects on aging, according to a recent study published in the Proceedings of the National Academy of Sciences. The research conducted by a team at King’s College London shed light on the intrinsic timekeeping mechanism within muscle cells that regulates protein turnover, ultimately impacting muscle growth and function.
The study revealed that at night, the muscle clock activates the breakdown of defective proteins, replenishing muscles while the body rests. Disrupting this intrinsic muscle clock was found to be associated with muscle decline typically seen with age, known as sarcopenia. This suggests that disturbing circadian rhythms, as seen in shift work, can accelerate the aging process.
The researchers used zebrafish in their study, as these organisms are commonly used in biological research due to their genetic similarity to humans. Zebrafish are easy to manipulate in the lab and their transparent bodies allow for easy observation of muscle tissues under a microscope.
Lead author Jeffrey Kelu, a Research Associate at King’s College London, explained that by impairing the muscle clock function in zebrafish, they were able to monitor the fish for two years and compare them to healthy controls. While no significant differences in muscle size were observed at younger ages, fish lacking a functional muscle clock showed signs of premature aging at two years, exhibiting characteristics of sarcopenia and overall decline in mobility.
Further investigations into protein turnover revealed that the muscle clock regulates the degradation of defective muscle proteins during rest at night, a process essential for maintaining muscle mass. The study highlighted the importance of nocturnal clearance in preserving muscle function, indicating that the accumulation of defective proteins may contribute to accelerated muscle decline in aged fish with a dysfunctional muscle clock and in shift workers.
Dr. Kelu emphasized the impact of circadian disruption on shift workers, noting that approximately four million individuals in the UK work shifts to keep businesses and emergency services operational around the clock. Understanding how circadian disruption contributes to sarcopenia is crucial for developing strategies to improve the health and well-being of shift workers. The researchers are currently conducting preclinical studies using drugs to modulate specific clock proteins, with the aim of developing therapies to prevent muscle decline in shift workers.
Co-author Professor Simon Hughes, an expert in developmental cell biology, highlighted the significance of studying muscle growth in zebrafish larvae as a model system, which can provide valuable insights for further research in humans. Overall, the study underscores the importance of circadian biology in understanding muscle health and aging, particularly in populations exposed to shift work.
In conclusion, the findings from this research suggest that circadian clocks play a crucial role in muscle health and accelerated aging in shift workers. By unraveling the mechanisms underlying circadian disruption and its impact on muscle function, future therapies may be developed to mitigate the effects of shift work on aging individuals. This study opens up new possibilities for improving the health and well-being of shift workers through targeted interventions based on circadian biology.
