While traditional reductionist molecular biology explains life phenomena as functions of individual elements, systems biology seeks to understand life phenomena by integrally analyzing the complex interactions between these elements. Dennis Noble’s work on the virtual heart demonstrates that the beating of the heart is caused by feedback effects between protein channels and muscle cells, illustrating the limitations of a reductionist approach. Systems biology offers a new research paradigm that explains the complexity of life phenomena through these interactions.
Conventional molecular biology has evolved through a reductionist approach that breaks down components into their individual functions. While this approach has contributed greatly to our understanding of how genes, proteins, and other compounds in cells work, organisms are not just a collection of components. Organisms are made up of many genes, proteins, and compounds that are constantly interacting in complex reactions, so a reductionist approach is not enough to understand the full picture of life. While it is important to identify the function of a single element, it is difficult to grasp the true nature of life phenomena unless we understand how they work in an integrated manner within the whole system.
Systems biology has emerged as an alternative approach to this problem. Systems biology has gained traction in recent years due to the massive accumulation of biological data on almost every organism, from bacteria to humans. The explosion of data has opened up new avenues for interpreting and predicting complex interactions that were previously impossible. It is now important to look beyond the function of individual components and explore how they are organized to function as a system.
Systems biologists seek to explain the high complexity of life phenomena by using accumulated biological data to identify the components involved in a particular life phenomenon and analyze how they interact with each other and with the systems that encompass them. They emphasize that life is not a simple machine, but a complex network. Understanding how small changes within a system affect the entire system is essential for a deeper understanding of life phenomena.
One way to do this is to use computers to create programs that operate on the same principles as living things, and then analyze their mechanisms. These simulation and modeling techniques can be used not only to explain life phenomena, but also to predict future life phenomena and develop new therapies or drugs.
Dennis Noble, the creator of the virtual heart, used this method to explain the feedback effects of heart muscle cells in the beating heart. Until now, the heart’s beating has been explained as a result of the flow of ions through protein channels in the cells, which causes voltage changes in the heart’s muscle cells. This is a classic example of the traditional reductionist approach, which attempts to explain complex phenomena through a single causal chain.
Dennis Noble, however, believed that the heartbeat is not the result of such a single cause-and-effect relationship, but rather the result of an interaction between components called protein channels and their superstructure, the muscle cells. He emphasized that this interaction is not just a physical process, but a complex one that involves the flow of information and reactions, and that this interaction is the main driving force that keeps the heart beating. To demonstrate this, they created a computer model of a living heart, and then ran experiments in which they left all other conditions unchanged and made it perform only those related to the feedback effect. In the process, they looked at changes in the voltage of muscle cells and changes in protein channels-potassium channels, calcium channels, and mixed ion channels.
First, in the first second, there were four oscillations of the cell voltage and corresponding oscillations of the protein channels. After the four oscillations, the cell voltage was held constant to stop the feedback from the cell voltage to the protein channels. If any one of the oscillations of the protein channel could produce an oscillation of the cell voltage, the protein channel would continue its original oscillation, resulting in an oscillation of the cell voltage. However, in the experiment, the protein channel oscillations stopped, and the lines showing the activity levels in each case flattened out. These results demonstrate that the heartbeat cannot be explained by the operation of the protein channels alone, and that feedback from the heart’s muscle cells to the protein channels is essential to generate the heartbeat.
These experiments show that life phenomena do not only occur in an upward causal direction, from genes or proteins to organelles or cells, but that the opposite downward causal direction is also important for life phenomena. Based on these experiments, Dennis Noble argued that it is necessary to move away from a reductionist approach centered on genes and take a holistic and integrative view of the various life phenomena within an organism. This is more than just an academic argument; it has important implications that call for a paradigm shift in life science research.
After all, systems biology seeks to explain life phenomena through a more holistic and integrative approach, based on the fact that all the components that make up life are interacting as a complex. It provides a direction for future life science research and will play an important role in deepening our understanding of various life phenomena.
