Recent scientific studies have found new information about parts of the cell, which may be related to longevity. For example, the researchers discovered that the size of the nucleolus (located inside of the cell’s nucleus) is associated with how long the cell—and subsequently how long the organism [a person]—will live.
Function of the Nucleolus
Unlike the nucleus, the nucleolus is an organelle that is NOT surrounded by a membrane. The primary function of the nucleolus is to make rRNA (ribosomal subunits from protein). Ribosomes make proteins; therefore, the nucleolus plays an important role in protein synthesis in the body. The nucleolus also helps to build other important substances, called “ribonucleoprotein particles” that impact all levels of information processing. Recent studies discovered that the nucleolus plays a major role in several functions in the body, including:
• The stress response
In a May 2018 review, published in the journal Trends in Cell Biology, Scientists reported their discovery of a connection between aging and the cell’s ribosome factory—aka, the nucleolus. The new study explains the link between age related pathways, such as in progeria, (a rare syndrome in children characterized by physical signs and symptoms suggestive of premature old age) and the nucleolus.
“The nucleolus is perceived as a basic housekeeper: It’s responsible for producing ribosomal RNA, which is important for the synthesis of proteins that are essential to the vitality of the cell,” says Adam Antebi, director of the Max Planck Institute for Biology of Aging in Germany, “But our work and other people’s work shows that the nucleolus plays many different roles, including lifespan control.”
Aging studies are oftentimes conducted on worms, because the average lifespan of a worm is just 30 days. This makes it relatively simple for the scientists to modify the genomes and wait to find out if the lifespan duration is affected. Antebi has noted that pathways related to aging, affect nucleolar size. For example, those organisms with enlarged nucleoli have shorter lifespans, compared to those with smaller nucleoli—having longer lifespans.
Scientists are not completely clear about exactly why a smaller nucleolus translates to a longer lifespan, but they hypothesize that it may have something to do with cell renewal and repair.
“Within an organism, within different tissues, it’s for sure that nucleolar size can vary quite a bit depending on the metabolic activities of the cells, so for example, in C. elegans, neurons have very small nucleoli whereas they are quite big in skin cells or muscle cells,” Antebi says. “It turns out that neurons in C. elegans maintain their structure well into old age, whereas muscle cells and skin cells tend to deteriorate more rapidly in the organism. Thus, even within an organism different tissues have different nucleolar size and it may reflect different rates of aging.”
The Nucleolus and Cell Growth
Interestingly, Antebi hypothesizes that the nucleolus, may be the area that controls the growth of the cell. When the cell doesn’t grow enough, it results in an inability to efficiently repair tissue. On the other hand, too rapid cell growth, results in cancer.
“The nucleolus is such an important organelle, it’s what has been selected to coordinate all of the different informational processes in the cell that bring protein and RNA together,” he says. “What is life but the proper processing of information and responding to environments in ways that are healthful for the cell and organism?”
Future Research Goals
Antebi says he plans to continue doing research to find out whether the nucleolus acts on a specific age-related pathway. He also aims to discover if the nucleolus is a biomarker (a sign in the body indicating disease). Future studies could help medical scientists estimate the level of health and longevity in people.
Trends in Cell Biology