Eat Me, We're Starving!

(October 4th, 2016) Congratulations to Yoshinori Ohsumi, who won the Nobel Prize in Physiology or Medicine for his discoveries of the mechanisms of authophagy.

He probably wasn't on many laureate prediction lists, he certainly wasn't on Thomson Reuters nor on ours, but that didn't keep the Nobel committee from awarding this year's Nobel Prize in Physiology or Medicine to Japanese cell biologist, Yoshinori Ohsumi. Born in 1945 in Japan, Ohsumi has dedicated his professional life to the study of autophagy (the degradation and recycling of cellular components) – first in yeast, then in human cells. Throughout his research and through, as the official press release states, “a series of brilliant experiments in the early 1990s”, Ohsumi identified the genes essential for autophagy and later functionally characterised the proteins encoded by the genes. Several experiments later, he and hence the scientific world, knew how the entire authophagy process is regulated and controlled.

In a 2009 interview, Ohsumi revealed what first got him started in autophagy research. “In 1988, I moved to the College of Arts and Sciences at the University of Tokyo as an associate professor. It was a small lab - just me and several instruments. At that time, I decided to study a lytic function of vacuoles as my main research theme. Nothing was known about what and how cellular proteins are degraded in this acidic compartment. It was hard to get a clear strategy from where I should start.

“In the life cycle of yeast, sporulation is a dramatic cell differentiation process, which is triggered by depletion of the nitrogen source from the environment. So, I thought bulk protein degradation must occur to this cell remodelling. At that time, not many people had observed the inside of the yeast cell by light microscope, though now fluorescence microscopic observation is quite popular for yeast researchers. The vacuole in yeast is the only organelle easily detectable under light microscope, so I had always observed them this way. One simple idea struck me. If vacuolar, proteinase-deficient mutant cells are shifted by the condition of nitrogen starvation, I might see some structures inside the vacuole, which had escaped from degradation. In fact, this proved to be the case. I found such clear and impressive morphological changes of the vacuole. Many vesicles, named autophagic bodies, were vigorously moving around in the vacuole. This was the just the starting point of my work on autophagy in yeast. It was quite natural that I started to introduce genetic screening to get autophagy-defective mutants by microscopy again.”

By the way, this is not the first time, autophagy research has been awarded a Nobel Prize. Back in 1974, Belgian scientist, Christian de Duve, who also coined the term “autophagy”, received the award for discovering the lysosome, an organelle containing hydrolytic enzymes and integral part of the autophagy machinery.

This machinery plays important roles in our cells, not only as a response to stresses, such as nutrient starvation, but also a way to get rid of microbial invaders and during cell differentiation. Asked, where Ohsumi sees his field of research going, he said in 2009: “There are so many problems that remain to be solved in membrane dynamics of autophagy, especially formation of autophagosome and various modes of autophagy, which are at present called collectively autophagy, but I think it is necessary to dissect them according to molecular mechanism.”

Once again, a single scientist has been honoured for an entire research field, a practice that has often been criticised. Thus our congratulations go out to all researchers, who, together with their hard-working teams, helped, through surely similarly brilliant experiments, to solve the autophagy puzzle.

Kathleen Gransalke

Photo: Mari Honda

Last Changes: 10.28.2016