Michael Young, a distinguished American geneticist, received the 2017 Nobel Prize in Physiology or Medicine. The award recognized his groundbreaking discoveries of the molecular mechanisms governing the circadian rhythm, significantly advancing understanding of how organisms synchronize biological processes with Earth’s daily rotation.
The Body’s Internal Clock
Circadian rhythms are natural, internal processes regulating the sleep-wake cycle and other biological functions, repeating roughly every 24 hours. These internal clocks allow organisms to anticipate and adapt to the regular rhythm of day and night. They influence an array of biological functions, including sleep patterns, feeding behavior, hormone release, blood pressure, and body temperature, ensuring an organism’s physiology and behavior are optimally synchronized with the day’s phases.
Unlocking the Genetic Secrets
Michael Young and his colleagues uncovered the genetic basis of these internal clocks, using fruit flies as a model organism. Their research identified specific genes controlling the daily biological rhythm. In 1984, Young isolated the period gene at Rockefeller University, known to influence circadian rhythms.
Investigations revealed the period gene’s protein, PER, accumulated in cells at night and degraded during the day, creating a 24-hour oscillation. In 1994, Young discovered a second gene, timeless, which produces the TIM protein. He demonstrated that for PER to enter the cell nucleus and inhibit period gene activity, it needed to bind with TIM. This interaction forms an inhibitory feedback loop regulating the internal clock.
Young also identified a third gene, doubletime, encoding the DBT protein. DBT delays PER protein accumulation, fine-tuning the oscillation to a 24-hour cycle. These discoveries established the biological clock’s mechanistic principles, revealing a complex network of reactions involving regulated protein phosphorylation and degradation.
Broadening Our Understanding of Life
Young’s discoveries profoundly impacted understanding of life. These findings established that a similar molecular mechanism controls circadian rhythms in nearly all multicellular organisms, including humans. A large proportion of our genes are regulated by this biological clock, making a well-calibrated circadian rhythm fundamental to physiological adaptation.
This understanding has significant implications for human health, shedding light on sleep disorders, jet lag, and shift work challenges. The field of chronomedicine, which optimizes medical interventions based on natural rhythms, has also benefited. The work laid groundwork for further research into other clockwork components, including light synchronization.
The Shared Nobel Recognition
Michael Young shared the 2017 Nobel Prize in Physiology or Medicine with Jeffrey C. Hall and Michael Rosbash. Hall and Rosbash, at Brandeis University, also isolated and characterized the period gene and demonstrated its protein’s oscillation. Their efforts, including identifying other genes partnering with period, led to the concept of a transcription-translation feedback loop, where gene products repress their own transcription, generating a self-sustaining oscillation.