By Kim Tong-hyung
Staff Reporter
A 25-year-old Korean researcher was among a team of scientists who have made a breakthrough into the mechanisms that regulate the inner workings of the human body. This may open new possibilities in drug development and contribute to identifying the causes of life-threatening illnesses such as cancer and diabetes, according to the Korean.
Choi Yoon-sup, a researcher at the Pohang University of Science and Technology (POSTECH), collaborated with colleagues at Stanford University and co-authored the article ``Robust, Tunable Biological Oscillations from Interlinked Positive and Negative Feedback Loops," which was published on the Internet version of U.S. magazine Science Friday.
It is already known that all chemical messengers in the human body are controlled by negative feedback loops, or a self-regulation process that responds to perturbation. For example, if the body's thyroxin rate rises higher than its regular level, negative feedback will reduce the output of the hormone to reestablish equilibrium. The regulation of body temperature, hormone synthesis and blood pressure are explained by this mechanism.
Scientists have also long known that a negative feedback loop of interacting genes or proteins generate the oscillators that control the biological rhythms of heart rate and cell cycles. What they didn't know was the role of the positive feedback loop, in which the system responds to perturbation in the same direction of the perturbation, found in many biological oscillators.
Now, Choi and his colleagues believe they have found an explanation for what advantages the extra loop imparts. In their study in Science, the researchers conclude the positive feedback loop may play a bigger role in providing the biological oscillators constant frequency and amplitude.
Researchers led by Princeton University's Stanislas Leibler made a breakthrough in 2000 when they successfully developed an artificial oscillatory circuit that was designed to provide negative feedback. However, the circuit failed to achieve the constant frequency and amplitude of the biological version, which controls the consistent rhythm of heart rates and cell cycles.
However, the Science authors, who tested a positive-plus-negative oscillator through their computational studies, achieved a widely tunable frequency and near-constant amplitude.
``In theory, the body could generate sustained oscillations with only negative feedback, but our studies show that a positive feedback has a crucial part in controlling the frequency and amplitude," Choi said.
``As this study may add new clues in defining the process of cell cycles, the knowledge could also add to the understanding of cancer, which is caused by cell expansions," he said.
Choi believes that the study has enormous potential for biotechnology, such as advancing the efforts to produce hydrogen energy through oscillators.