The so-called junk DNA was long thought to have no important role in heredity or disease because it does not code for proteins.
However, emerging research in recent years has revealed that many of these sections of the genome produce RNA molecules that, despite not being proteins, still have important functions in the body. RNA is a close chemical cousin to DNA.
Molecules now associated with these sections of the genome are called noncoding RNAs. Of these, about 90 per cent are called long noncoding RNAs.
In a recent issue of the journal Circulation, researchers from Washington University School of Medicine in St Louis, have reported results from the first comprehensive analysis of all RNA molecules expressed in the human heart.
The researchers studied nonfailing hearts and failing hearts before and after patients received pump support from left ventricular assist devices (LVAD).
The LVADs increased each heart's pumping capacity while patients waited for heart transplants.
"We took an unbiased approach to investigating which types of RNA might be linked to heart failure," said senior author Jeanne M Nerbonne, the Alumni Endowed Professor of Molecular Biology and Pharmacology.
"We were surprised to find that long noncoding RNAs stood out. In fact, the field is evolving so rapidly that when we did a slightly earlier, similar investigation in mice, we didn't even think to include long noncoding RNAs in the analysis," Nerbonne said.
Heart failure refers to a gradual loss of heart function. The left ventricle, the heart's main pumping chamber, becomes less efficient. Blood flow diminishes, and the body no longer receives the oxygen needed to go about daily tasks.
Sometimes the condition develops after an obvious trigger such as a heart attack or infection, but other times the causes are less clear.
In the new study, the investigators found that unlike other RNA molecules, expression patterns of long noncoding RNAs could distinguish between two major types of heart failure and between failing hearts before and after they received LVAD support.
"We don't know whether these changes in long noncoding RNAs are a cause or an effect of heart failure. But it seems likely they play some role in coordinating the regulation of multiple genes involved in heart function," Nerbonne said.


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