SYSTEMS BIOLOGY: EVOLUTION OF A NEW DISCIPLINE

Reductionism has been described as the attempt to explain complex phenomenon by defining the functional properties of the individual components that compose multi-component systems 1 . Most biological and biomedical research has traditionally followed a reductionist approach. While this has undoubtedly helped to reveal great depths of knowledge of biological systems such approaches, however, are limited in their ability to decipher a more global level of understanding of the complexity of biological phenomenon. In contrast to reductionist strategies, systems approaches are those that adopt a more ‘holistic’ perspective towards the resolution of biological phenomena and processes. The core precept of systems biology is that complex biological processes cannot be attributed to individual molecular entities. Rather, information on properties of the individual components needs to be integrated in order to arrive at a comprehensive or systems view. Recent successes achieved through the application of systems-level analysis have emphasized that biomedical research needs to move away from “naive reductionism” or the belief that the complete understanding of living organism and systems can be achieved by this approach 1, 2 . Systems biology is an integrative, and interdisciplinary, approach in biology which aims to understand and predict the behaviour or “emergent” properties of complex, multicomponent biological systems and processes 1 . It is a relatively new approach with the potential of completely transforming how we understand biological problems and tackle disease. The systems approach attempts to integrate information regarding the components of a system (depending on the system under study these could be genes, proteins, organs etc), the component dynamics (how they function and regulate each other), and finally, the manner in which this regulates biological processes. This discipline integrates concepts from mathematics, computer science, engineering and physics to understand biological complexity (Figure 1). Systems approaches are believed to be holistic and not atomistic. They employ hypothesis-driven as well as discovery-driven approaches. They are designed to address the complexity of biological systems, both normal and perturbed, at multiple levels of organization (from molecules, cells and organs to organisms and ecosystems) 3-6 . A hallmark of biological systems is their non-linear behaviour, and an understanding of the basis and consequences of such behaviour can only be approached by using the tools of systems biology. The general systems approach can be explained with the example of any machine, for example a car. The traditional reductionists would limit their study to deciphering the functioning of each part, without an attempt to decipher how they all come together. Though such approaches can help entangle the individual components of a complex machine, they however fail to provide any insights on how these parts must be assembled in the correct manner so as to recreate the car with the properties, as we know it. On the other hand, systems based approaches would attempt to integrate the individual properties of each part within the context of the appropriate structural organization.