The 2016 Physiology or Medicine Nobel Prize has been awarded to Yoshinori Ohsumi for his "discoveries of the mechanisms for autophagy". The Japanese researcher, an emeritus professor at Tokyo Institute of Technology, has worked for more than two decades to improve scientific knowledge about this important cellular process.
Autophagy is a natural physiological process in the body that deals with destruction of certain cells. It is a process by which cells can recycle part of their own content. The term comes from the Greek for "self-eating" and indeed, it mediates the digestion and recycling of non-essential parts of the cell.
Autophagy also has the capacity to clear invading microorganisms and toxic protein aggregates, and thus can play a crucial role during infection, in ageing and in the development of many human illnesses.
While the process was identified in the 1960s, little research was subsequently dedicated to it, meaning the way autophagy worked remained a mystery for years.
Many questions remained until the 1990s, when Ohsumi began pioneering work on the subject, for which he is now rewarded. Until then, it was not clear how the autophagy process was initiated, how important it was for cellular and organismal survival - and its role against diseases was not well understood.
Different autophagy processes
Working with yeast as a model, and then with mammalian animal models, Ohsumi and his team learnt more about the molecular machinery of autophagy in the body and identified genes driving the process. They showed for example that mice lacking a gene known as Atg5 gene were apparently normal at birth, but died during the first day of life.
Different forms of autophagy were also later identified. One of them is macroautophagy, which degrades large portions of the cytoplasm and cellular organelles in the cells. Another, selective autophagy, targets specific protein aggregates, cytoplasmic organelles or invading viruses and bacteria - and is therefore very interesting to study to better understand the body's fight against diseases.
Autophagy is induced in response to different types of stress on the body, and, based on Ohsumi's research, it has been shown to have a protective function and a capacity to counteract cell injury and many diseases associated with ageing.
The discovery of autophagy genes, and the molecular machinery behind this crucial cellular process have led to a new paradigm in the understanding of how the cell recycles its contents. Understanding autophagy's role in fighting off certain diseases and infections has contributed greatly to medical advances.