Aging is an inevitable process associated with an overall decline of organs, tissues, and cells. But what aging looks like on a cellular level may depend on what organ you’re talking about, a new study suggests.
The finding, published this month in the journal Cell Systems, could help us better understand age-related diseases tied to specific organs, such as heart disease or dementia.
“We were surprised by these very different networks” driving aging in different organs, says study coauthor Martin Hetzer, co-director of the Glenn Center for Aging Research at the Salk Institute in California. “It gives us a new angle, a new perspective on age-related diseases.”
Many age-related diseases are associated with abnormalities in proteins, such as the buildup of amyloid protein in the brains of patients with Alzheimer’s disease. So Hetzer and colleagues decided to take a close look at protein changes during the aging process.
They compared the livers and brains of 6-month-old mice — the equivalent of a young human adult’s organs — with those of 24-month-old mice, similar to a senior citizen’s.
In a string of experiments analyzing those organs, the researchers sought out molecular changes affecting the abundance of proteins in cells, and also looked for where proteins were located in cells. They identified over 450 differences in the abundance of proteins between the young and old organs, and 130 proteins that changed locations in the cells from young to old.
But perhaps the most striking finding was that the age-related changes weren’t the same in the liver and brain: Each organ aged in a different way. In the liver, for example, the scientists detected significant changes in proteins involved in metabolic processes, pathways by which cells use and produce energy. In the brain, on the other hand, aging primarily affected proteins associated with cell organization.
The researchers haven’t yet determined if one organ is aging faster than another, but they are now doing additional studies — on both rodent and human tissue — to find out. They are also taking a peek at other organs, including the heart and pancreas.
“We really want to get a sense of what are the problems that occur for each organ during aging,” says Hetzer, “and then put everything together to understand how aging affects the entire organism.”