NEW YORK (AP) " Like a busy city, a cell works better if it can dispose of and recycle its garbage. Now a Japanese scientist has won the Nobel Prize in medicine for showing how that happens.
The research may pay off in treatments for diseases such as cancer, Parkinson's and Type 2 diabetes.
Yoshinori Ohsumi, 71, of the Tokyo Institute of Technology, was cited Monday for "brilliant experiments" that illuminated autophagy, in which cells gobble up damaged or worn-out pieces of themselves. Autophagy means "self-eating."
That process helps keep cells healthy by producing nutrients and building blocks for renewal, making way for new cellular structures and clearing out invading germs and clumps of proteins that could cause disease.
Abnormalities in autophagy (aw-TAH'-fuh-jee) occur in several diseases, including Parkinson's, Alzheimer's, diabetes and cancer, and more than 40 studies in humans are under way to test drugs to boost or depress the process, Nobel officials said.
Cancer cells, for example, take advantage of autophagy to promote their own survival. Many research groups are exploring a strategy of fighting the disease by reducing these cells' use of the cleanup process, said Eileen White, a researcher at the Rutgers Cancer Institute in New Brunswick, New Jersey.
Ohsumi said he never thought he would win a Nobel for his work, which involved studying yeast under the microscope day after day for decades.
"As a boy, the Nobel Prize was a dream, but after starting my research, it was out of my picture," he told reporters in Tokyo.
"I don't feel comfortable competing with many people, and instead I find it more enjoyable doing something nobody else is doing," Ohsumi added. "In a way, that's what science is all about, and the joy of finding something inspires me."
The prize is worth 8 million kronor, or $930,000.
Ohsumi was honored for work he did in the 1990s. Nobel judges often award discoveries made decades ago, to make sure they have stood the test of time.
Working in yeast, Ohsumi developed a way to identify key genes involved in autophagy and went on to discover the first genes known to play a role. He then showed how autophagy is controlled by specific proteins and complexes of proteins.
"He actually unraveled which are the components which actually perform this whole process," said Rune Toftgard, chairman of the Nobel Assembly.
Scientists were aware of autophagy before Ohsumi's work, but they "didn't know what it did, they didn't know how it was controlled and they didn't know what it was relevant for," said David Rubinsztein, deputy director of the Institute for Medical Research at the University of Cambridge.
Ohsumi's work "opened the door to a field," he said. "It provided tools to the whole world to start trying to understand how autophagy is important" in mammals. Now "we know that autophagy is important for a host of important mammalian functions."
For example, scientists said, it springs into action to provide energy when the body is running short on nutrients, such as when a person skips meals or a newborn has not yet begun breastfeeding.
Autophagy also removes proteins that clump together abnormally in brain cells, which is what happens in conditions like Huntington's and Parkinson's diseases and some forms of dementia. Animal studies suggest that boosting autophagy can ease and delay such diseases, said Rubinsztein, whose lab is pursuing that approach.
"As time goes on, people are finding connections with more and more diseases," he said.
In Tokyo, Ohsumi said many details of autophagy are yet to be understood and he hopes younger scientists join him in looking for the answers.
"There is no finish line for science. When I find an answer to one question, another question comes up. I have never thought I have solved all the questions," he said. "So I have to keep asking questions to yeast."
It was the 107th award in the medicine category since the first Nobel Prizes were handed out in 1905.
Last year's prize was shared by three scientists who developed treatments for malaria and other tropical diseases.
The announcements continue with physics on Tuesday, chemistry on Wednesday and the Nobel Peace Prize on Friday. The economics and literature awards will be announced next week.
The awards will be handed out at ceremonies in Stockholm and Oslo on Dec. 10, the anniversary of prize founder Alfred Nobel's death in 1896.
Karl Ritter reported from Stockholm. Associated Press writers Keith Moore in Stockholm and Mari Yamaguchi in Tokyo contributed to this report.
This story has been automatically published from the Associated Press wire which uses US spellings