Yoshinori Ohsumi

Yoshinori Ohsumi was born in Fukuoka,Japan in 1945. He studied autophagy, for which he is receiving the Nobel Prize. The word autophagy means “self eating” and is derived from the Greek language. In the human body, autophagy is a process by which our cells reuse their own components to release energy and to build new functional parts. Yoshinori Ohsumi decided to study the process of autophagy in Baker’s yeast.

Yeast cells contain a single large lysosome known as a vacuole. Ohsumi found a clever way to visualize the accumulation of autophagosomes in the vacuole by making starved cells unable to degrade the content of the vacuole. He then used this method to search among thousands of mutants for yeast cells that had lost the capacity to activate autophagy. This led to the discovery that autophagy is regulated by a large number of genes. As many as 15 essential autophagy genes were identified in the first study, published in 1993. Ohsumi moved onto the next question, which was to understand how the products of these genes work together.

We now have a detailed understanding of the molecular mechanism of autophagy. We now know that autophagy regulates important physiological functions of the cells and that the effects of autophagy are associated with many human diseases. Through the removal of damaged proteins and organelles, autophagy promotes cell renewal. Failure of autophagy is therefore associated with cell aging and with diseases of old age, such as Alzheimer’s disease and type two diabetes.

Finally, too much autophagy might have undesired effects, such as with cancer, where autophagy might promote growth of the tumor cells. It is hopeful that the discoveries of Ohsumi will help with the treatment of many diseases.