You know how many birthdays you’ve had, but that doesn’t mean all your organs are aging at the same rate.
Why should you care?
Because as organs age, they start to deteriorate.
If we can figure out how different organs age, we may learn how to prevent age-related conditions such as Alzheimer’s disease.
New research reveals how cellular proteins in the livers and brains of rats age differently. Details of the study are published in the journal Cell Systems.
“Changes that occur in aging can be diverse and difficult to pin down, and looking simply at one parameter might result in not seeing the whole picture,” said co-first author Brandon Toyama, Ph.D., of the Salk Institute for Biological Studies.
A team of researchers set out to see that whole picture.
One of the study’s senior authors, Martin Beck, Ph.D., of the European Molecular Biology Laboratory, told Healthline that different tissues have a different capacity for self-renewal.
A good example of that is the difference between the liver and the brain.
“Liver cells divide throughout life. Brain cells do not and they do contain molecules that are essentially there for life,” said Beck. “We were thus interested to determine how differentially affected these two organs are by aging. We were also interested in which types of molecules are most affected — RNAs or proteins.”
What the Research Showed
State-of-the-art technology helped the team see age-dependent changes for the first time.
The researchers used genomics and proteomics. That’s how they were able to simultaneously analyze changes in transcription, translation, protein levels, alternative splicing, and protein phosphorylation.
“We compared the content of RNA (gene expression) and protein of young and old tissues,” said Beck. “We also measured protein synthesis rates and so-called post-translational modifications [the latter is chemical modifications of proteins].”
This helped them gain a complete view of protein differences in livers and brains of young and old rats.
The team found 468 differences in protein abundance between the two groups. These were mostly due to changes in protein synthesis.
Another set of 130 proteins showed age-related changes in their location within cells, phosphorylation state, or splice form. These changes may affect the activity level or function of the proteins.
Most of the age-related protein differences were specific to one organ.
In the liver, cells are regularly replenished. So are its proteins.
It’s a different story in the brain. There, most neurons must last for a lifetime. Older proteins make the brain more susceptible to loss of function over time.
“The major technical innovation here is that it determines the effect of aging on multiple levels,” said Beck.
Why We Need to Study Aging
The study of aging is about more than gray hair and wrinkles.
Researchers want to learn if one organ can affect the aging of another. The answers could help us understand aging and age-related diseases.
They’ll also study the role of genetic variability in aging.
“Such studies will be broadened beyond the population level,” said Beck. “The influence of individual lifestyles and genetic backgrounds have to be determined.”
This study provided a large blueprint of molecules affected by age. The researchers hope it will lead others to further investigate the mechanism of aging.
“We found that the molecular content of brain and liver is mostly affected in an organ-specific way by age, e.g., molecular factors involved in cell communication are specifically affected in brain,” said Beck. “There are, however, exceptions, molecules that are similarly affected in both organs. Those systemic effects might be promising starting points to develop treatments.”
Understanding how different organs age could someday help prevent or treat age-related diseases.
“Of course, one wants to better understand aging in order to identify new targets for drugs,” said Beck.
Beck said this particular study didn’t take lifestyle factors, such as diet, into account. He does believe such studies are technically feasible and are likely to happen in the near future.
We’re living longer than ever. Research into aging might be able to help us live better.