Distinguished Lecture

Honorary Professor Yoshinori Ohsumi, Ph.D.
Ohsumi Frontier Science Foundation
The Nobel Prize in Physiology or Medicine 2016

Yoshinori Ohsumi was born in Fukuoka, Japan. He studied at the University of Tokyo where he received his doctoral degree in 1974. After a few years at Rockefeller University, New York, he returned to the University of Tokyo. He started to work on the lytic function of the vacuole, then found yeast autophagy by light and electron microscopy. He performed a genetic screen for autophagy-defective mutants. His group got 18 genes essential for starvation-induced autophagy. However, up to now, Dr. Ohsumi has focused on dissection of the mechanism of the Atg proteins in yeast at a molecular level.
In 2009, he moved to Tokyo Inst. of Tech. and received the Nobel Prize in Physiology or Medicine for the elucidation of mechanisms for autophagy. He continues to elucidate the membrane dynamics and the physiological relevance of autophagy in the same university.

In addition to the research, he established the Ohsumi Frontier Science Foundation in 2016 for the development of basic science and he is working hard to the development of the basic science.

Message from the Scientific Program Committee

The SCCJ as the host society of the 31st IFSCC Congress 2020 Yokohama (The Virtual Congress) is honored to introduce the Distinguished Lecture given by Professor Dr.
Yoshinori Ohsumi. Dr. Ohsumi received “The Nobel Prize in Physiology or Medicine in 2016”, for his discoveries of mechanisms for autophagy.

In his presentation, Dr. Ohsumi presents his work on autophagy, a fundamental process for degrading and recycling cellular components, entitled “Lessons from yeast-autophagy as a cellular recycling system”. During Dr. Ohsumi’s presentation, animal experiments will be introduced to show the importance and diverse physiological role of autophagy in mammals. We emphasize that Dr. Ohsumi’s work is purely based on science, and not related to any cosmetics research.

Please enjoy Dr. Ohsumi’s long and fruitful journey on autophagy!

Abstract

Lessons from Yeast – autophagy as a cellular recycling system

              Since the establishment of the central dogma, biologists’ efforts have been focused on understanding the process of protein synthesis (i.e. gene expression), whereas protein degradation had been thought to be passive and less important. Now it is becoming clear that every cellular activity is maintained by a delicate balance between continuous synthesis and degradation, and that degradation is equally as important as synthesis.
             Autophagy, which is the intracellular degradation of cytoplasmic components in the lysosome, was first observed in the early 1960s, but remained unexamined and poorly understood for many years. Three decades ago I used a simple microscope to discover the massive delivery of cytoplasmic portions to the vacuole in nutrient starved yeast cells. Electron microscopy revealed that the membrane dynamics of this process were similar to known macroautophagy in mammals. Subsequently, we identified many autophagy-defective mutants. We know that 18 ATG genes are essential for starvation-induced autophagy in yeast. Their gene products, the Atg proteins, function in concert to sequester cytoplasmic constituents into autophagosomes. The Atg proteins work together as six functional units, including an Atg1 kinase complex, the PI3 kinase complex and two unique ubiquitin-like conjugation systems. Soon we found that most ATG genes are well conserved from yeast to mammals and plants, indicating that autophagy was acquired at early stage of eukaryotic evolution. The identification of ATG genes completely changed the landscape of autophagy research. Using the Atg proteins as a tool, we could visualize the progress of autophagy in various organisms and tissues, and the genetic manipulation of ATG genes unveiled a truly broad range of physiological functions of autophagy. Autophagy plays critical roles not only in nutrient recycling, but also intracellular clearance through the elimination of harmful proteins and damaged organelles. It is becoming clear that autophagy is relevant to many diseases. Since autophagy is one of the most fundamental functions of cell, it must fulfill various functions depending on the physiological demands of different cell types.
             We have learned much about molecular mechanism of autophagy using the simple yeast system, but many fundamental questions still remained to be answered. The present knowledge of autophagy in yeast and future perspectives on research will be discussed.
Further efforts will be needed to understand the various functions of autophagy in multicellular mammalian systems composed of diverse cell types.