You likely know someone who seems to age slowly, appearing years younger than their birth date suggests. And you likely have seen the opposite – someone whose body and mind seem much more ravaged by time than others. Why do some people seem to glide though their golden years and others physiologically struggle in midlife?
I have worked in the field of aging for all of my scientific career, and I teach the cellular and molecular biology of aging at the University of Michigan. Aging research doesn’t tend to be about finding the one cure that fixes all that may ail you in old age. Instead, the last decade or two of work points to aging as a multi-factoral process – and no single intervention can stop it all.
What is aging?
There are many different definitions of aging, but scientists generally agree upon some common features: Aging is a time-dependent process that results in increased vulnerability to disease, injury and death. This process is both intrinsic, when your own body causes new problems, and extrinsic, when environmental insults damage your tissues.
Your body is comprised of trillions of cells, and each one is not only responsible for one or more functions specific to the tissue it resides in, but must also do all the work of keeping itself alive. This includes metabolizing nutrients, getting rid of waste, exchanging signals with other cells and adapting to stress.
Aging results from a number of physiological factors.
The trouble is that every single process and component in each of your cells can be interrupted or damaged. So your cells spend a lot of energy each day preventing, recognizing and fixing those problems.
Aging can be thought of as a gradual loss of the ability to maintain homeostasis – a state of balance among body systems – either by not being able to prevent or recognize damage and poor function, or by not adequately or rapidly fixing problems as they occur. Aging results from a combination of these issues. Decades of research has shown that nearly every cellular process becomes more impaired with age.
Repairing DNA and recycling proteins
Most research on cellular aging focuses on studying how DNA and proteins change with age. Scientists are also beginning to address the potential roles many other important biomolecules in the cell play in aging as well.
One of the cell’s chief jobs is to maintain its DNA – the instruction manual a cell’s machinery reads to produce specific proteins. DNA maintenance involves protecting against, and accurately repairing, damage to genetic material and the molecules binding to it.
Proteins are the workers of the cell. They perform chemical reactions, provide structural support, send and receive messages, hold and release energy, and much more. If the protein is damaged, the cell uses mechanisms involving special proteins that either attempt to fix the broken protein or send it off for…
