Scientists shed light on braking mechanisms in cellular signaling

Jun 05, 2014

A team of researchers studying a flowering plant has zeroed in on the way cells manage external signals about prevailing conditions, a capability that is essential for cells to survive in a fluctuating environment.

Researchers at UC Berkeley, the Plant Gene Expression Center, UC San Francisco, and the Carnegie Institution for Science identified a novel mechanism by which the strength of such an external signal is reduced, or attenuated. Their work focuses on the tiny mustard plant Arabidopsis, which is frequently used by scientists as an experimental model. Their findings are published in Science June 6.

Attenuation of signaling is analogous to the brakes on a car. While acceleration is desirable, acceleration without restraint can be disastrous. In this research, Arabidopsis seedlings were taken from subterranean darkness into sunlight, which triggered a response leading to "rapid and extensive" redirection of , ultimately resulting in familiar green seedlings.

But a brake on this acceleration of new gene expression is also necessary to restabilize the cells at a new equilibrium. The research team discovered a nuclear-localized, bimolecular signaling configuration by which the braking mechanism is directly linked to the accelerator, thereby providing simultaneous acceleration and restraint. By identifying the mechanism involved in this attenuation process, the team's discovery has potential implications ranging from agricultural to cancer research.

Cellular signaling triggered by external cues such as sunlight enables organisms to adapt to the prevailing conditions. When the organism perceives something that requires a response, a series of chemical signals is activated. This signaling is generally very robust at first. But at some point it is necessary to dial it back or turn it off entirely—a restraint that falls to different, less-understood signaling pathways. These types of restraint functions are of great importance but poorly understood, as scientists have focused mostly on how the cells get stimulated in the first place.

Light-signaling in Arabidopsis involves the binding of an activated photoreceptor molecule (called phytochrome) to a transcription factor (gene-switch) called PIF. This binding destroys PIF, switching off its target genes. However, the researchers found that in imposing PIF's destruction, phytochrome signs its own death warrant and is simultaneously executed, thus reducing the incoming light-signaling intensity.

"Understanding such molecular mechanisms underlying the light response kinetics is important for engineering crops that can better adapt to environmental fluctuations," said Carnegie's Zhiyong Wang, one of the co-authors.

This bimolecular mutually assured destruction (MAD) mechanism of signaling attenuation appears to represent a new configuration, thus broadening our understanding of the range of mechanisms nature has evolved for this critical function.

Explore further: Membrane proteins: Communicating with the world across the border

More information: "A mutually assured destruction mechanism attenuates light signaling in Arabidopsis" www.sciencemag.org/lookup/doi/… 1126/science.1250778

Related Stories

Internal clock, external light regulate plant growth

Jul 09, 2007

Most plants and animals show changes in activity over a 24-hour cycle. Now, for the first time, researchers have shown how a plant combines signals from its internal clock with those from the environment to show a daily rhythm ...

A tiny RNA with a big role in melanoma

Feb 18, 2014

A Yale-led study has identified a key mechanism in the regulation of gene expression that promotes the proliferation of melanoma cells. The finding opens a possible avenue for development of treatments that ...

Plants on Steroids: Key Missing Link Discovered

Sep 08, 2009

(PhysOrg.com) -- Researchers at the Carnegie Institution's Department of Plant Biology have discovered a key missing link in the so-called signaling pathway for plant steroid hormones (brassinosteroids). Many important signaling ...

Recommended for you

Compound from soil microbe inhibits biofilm formation

7 hours ago

Researchers have shown that a known antibiotic and antifungal compound produced by a soil microbe can inhibit another species of microbe from forming biofilms—microbial mats that frequently are medically harmful—without ...

Researcher among best in protein modeling contests

11 hours ago

A Purdue University researcher ranks among the best in the world in bioinformatics competitions to predict protein structure, docking and function, making him a triple threat in the world of protein modeling.

Survey of salmonella species in Staten Island Zoo's snakes

12 hours ago

For humans, Salmonella is always bad news. The bacterial pathogen causes paratyphoid fever, gastroenteritis and typhoid. But for snakes, the bacteria aren't always bad news. Certain species of Salmonella are a natural part ...

A long-standing mystery in membrane traffic solved

Mar 27, 2015

In 2013, James E. Rothman, Randy W. Schekman, and Thomas C. Südhof won the Nobel Prize in Physiology or Medicine for their discoveries of molecular machineries for vesicle trafficking, a major transport ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.