Scientists shed new light on workings of genetic regulation

January 25, 2016
The "life cycle" of an mRNA in a eukaryotic cell. RNA is transcribed in the nucleus; processing, it is transported to the cytoplasm and translated by the ribosome. Finally, the mRNA is degraded. Credit: Public Domain

A team of scientists has uncovered greater intricacy in protein signaling than was previously understood, shedding new light on the nature of genetic production.

Christine Vogel, an assistant professor in New York University's Department of Biology and one of the study's senior authors, explains that "to make a protein, we need to make a messenger RNA molecule from the gene encoded in the DNA, and then, in a second process, make proteins from these RNA molecules. Both processes are highly regulated and coupled."

This coupling is similar to the coupling between a moving escalator and a person walking on it at the same time.

The research, which appears in the journal Molecular Systems Biology, takes a closer look at how the two coupled processes change in the cell responding to an outside stimulus.

"Until recently, it has been very difficult to study these systems and researchers have thought that the movement of the escalator is most important during the cellular response," Vogel explains. "We now show that is not necessarily the case, and under some circumstances, the person's walking determines the overall outcome."

In biology, this means that both of the processes—to make RNAs and proteins—play important roles, but with different patterns.

In their study, the scientists, who also included researchers from National University Singapore and Berlin's Max-Delbruck-Center, took a closer look at how the two processes exactly respond over time.

Their results showed notable distinctions between DNA and mRNA in the nature of their signaling. Notably, the process of making RNA from DNA was pulse-like—a brief messaging over the studied period that returned to the normal levels by the end of the measurements. By contrast, the process of making a protein from RNA was akin to an on/off switch: once started, levels remained constant for consistent periods before reverting back to long stretches of dormancy.

While the reasons for these differences in cell behavior remain unknown, the researchers believe the answer may lie in the nature of the two tasks.

"It is very costly for the cell to make proteins, but making RNA messages from DNA is a relatively low-energy and simple process, so it makes sense that we see frequent, or pulsating, signaling at this stage," observes Vogel. "By contrast, creating proteins is an intricate undertaking, requiring a great deal of time and energy. This may be why, once you decided to stop production of proteins, you do not turn it back on that easily—and the other way around."

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