A Colorado State University study published today in the Annals of Medicine shows that most genes of living things – mammals and plants – are expressed in rhythm. The discovery lends new clues to genetic changes during aging and disease.
The study shows that genes are actually expressed much like two cogs in a wheel, working together to create a normally functioning gene. Historically, scientists have believed that most genes are expressed constantly. This new information helps scientists to better understand how genes interact to maintain life.
“This study reviews data from multiple authors and sources and shows that life is structured in time dimension. Genes are expressed in rhythm naturally. When a special function requires constant activity of a gene, two versions can be produced, working in waves opposite each other to create what looks like a constant expression,” said Andrey Ptitsyn, a researcher in the Department of Microbiology, Immunology and Pathology at Colorado State University. The department is part of the College of Veterinary Medicine and Biomedical Sciences. “This is important in understanding what can go wrong with gene expression. If the mechanisms that expresses genes are rhythmic, what happens if they become out of sync? This new understanding gives you knowledge to discover and untangle the complex network of genes.”
Ptitsyn and his research partner, Jeffrey Gimble from Pennington Biomedical Research Center at Louisiana State University System, believe that mechanisms that fall out of sync cause illnesses, leading to complications. For example, slow, subtle changes in rhythmic genetic expression may cause illnesses associated with aging or diseases.
"We hope that this review article prompts other investigators in the field to test the hypothesis that a majority of transcripts oscillate in any given tissue,” said Gimble, a professor in the Stem Cell Biology Lab at Pennington Biomedical Research Center. “Reproduction of this work by independent labs will go a long way to determining how circadian biology has an impact on metabolism."
The researchers have reviewed data from government, academic and private sources, including genetic function of humans, rats, mice, fruit flies, plants and mosquitoes.
The researchers believe that the expression of some groups of genes is tied closely to circadian rhythms. Circadian rhythms are biological rhythms that cycle over a period of about 24 hours and regulate timing for most physiological functions and behaviors such as sleeping, eating and activity. Circadian rhythm is closely interlinked with metabolic rhythms, driven by the biochemical processes that power up all biological functions. Gene activity oscillates in an orchestrated system and gene expression can be impacted by daylight, meals and sleeping – or a lack of such. Functionally related groups of genes can work in an orchestrated manner: some fire in succession, some peak at the same time. Shifting daily activities in time can synchronize patterns on a molecular level.
“Most biology text books do not provide enough information about how gene expression patterns are orchestrated in time. New studies in this area provide keys to decipher the complexity of thousands of genes working in symphony – or going out of tune to cause a disease,” Ptitsyn said.