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Japan's Yoshinori Ohsumi wins Nobel Prize in medicine

Yoshinori Ohsumi (Mainichi)

Yoshinori Ohsumi, honorary professor at Tokyo Institute of Technology, has won this year's Nobel Prize in physiology or medicine for clarifying autophagy, the Nobel Assembly at Karolinska Institute in Stockholm said on Oct. 3.

Ohsumi has clarified a phenomenon called autophagy, in which living organisms degrade protein in their cells at a molecular level. He has identified a gene indispensable for this function and thereby clarified the basic function supporting life activities. It has already been confirmed that autophagy is related to human cancer and aging. His medical research that led to clarifying the causes of diseases and treatment methods has been well appreciated.

This is the third consecutive year that a Japanese person has won a Nobel Prize. In 2015, Satoshi Omura, professor emeritus at Kitasato University, won the Nobel Prize in physiology or medicine and Takaaki Kajita, head of the Institute for Cosmic Ray Research at the University of Tokyo, captured the Nobel Prize in physics.

The success of 71-year-old Ohsumi brought the number of Japanese Nobel laureates to 25, including Shuji Nakamura, who was born in Japan and later became an American citizen, and Yoichiro Nambu, a Tokyo-born U.S. scientist.

Of the 25 Nobel laureates, four won the prize in physiology or medicine, 11 in physics and two in literature, while one was given the peace prize.

The award ceremony for Ohsumi is scheduled to be held in Stockholm on Dec. 10, and Ohsumi will receive 8 million Swedish krona, or about 95 million yen, in prize money.

Living organisms try to overcome a state of starvation by reworking their own cells or falling into a dormant state. This has been known for many years from the fact that some mammal species hibernate and slime mold forms spores from an amebic state.

Christian de Duve, a Belgian researcher who won the Nobel Prize in physiology or medicine in 1974, confirmed the function of cells degrading their own protein while analyzing internal organs of mice in the 1960s. He named this function autophagy, but the function had not been clarified at the molecular level.

In 1988 when he was associate professor at the University of Tokyo, Ohsumi found through observations using a microscope that when yeast cells, a kind of microorganism, are placed in a state of malnutrition and starvation, small particles accumulate in small organs called vacuoles. In the process of autophagy, yeast brings protein and other substances in their cells into their vacuoles and degrades these substances using various kinds of enzyme.

Moreover in 1993, Ohsumi discovered 14 types of yeast that never cause autophagy even if they are put in a state of starvation. After comparing these yeast cells with normal yeast, he identified the gene that triggers autophagy. This gene has also been found in the cells of various animals and plants. As such, his achievements served as a major breakthrough in research into this field.

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Yoshinori Ohsumi was born in 1945 in Fukuoka. He received a Ph.D. from the University of Tokyo in 1974, and became a researcher at the Rockefeller University in New York. In 1988 he was appointed as assistant professor at the University of Tokyo and two months later he encountered autophagy. Ohsumi received the title of honorary professor from Tokyo Institute of Technology in 2014. He received a Thomson Reuters Citation Laureates prize in 2013. In 2015 Ohsumi received a Gairdner Foundation International Award, the International Prize for Biology and the Keio Medical Science Prize.

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