Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Cellular dumping site is not garbage after all


Cells can reuse the chemical messengers that carry genetic information to the machinery that makes proteins. Sometimes cells shuttle the messengers to storage and later reactivate them to make proteins, according to new research.

This image shows P-bodies, in red, surrounding the nucleus of a human tumor cell. The red color indicates that the P-bodies contain the protein RCK. Photo credit: John Bloom.

Learning how cells regulate the newly discovered "mRNA cycle" may provide insights into how the cellular machinery runs amok in diseases like cancer.

Scientists had previously thought the messenger molecules, known as mRNAs, were manufactured, used, decommissioned and then sent on a one-way journey to the garbage dump.

These cellular garbage dumps, called P-bodies, turn out to be storage depots, not landfills. After use, mRNA molecules are temporarily deactivated for storage purposes. The cell can then either destroy the mRNA or recondition pre-used mRNA so it can be put back into service if needed.

P-bodies are also involved in determining whether specific mRNAs are used to make proteins, a process called translation.

"We were surprised to find that the P-bodies were involved in regulating translation," said research team leader Roy Parker, a Regents’ Professor of molecular and cellular biology at The University of Arizona in Tucson and an Investigator with the Howard Hughes Medical Institute. In 2003, his lab was the first to name and describe a function for P-bodies.

Parker said of the new finding, "It suggests P-bodies have a much broader role in controlling the activities of the cell than we realized."

Parker and first author Jeff Coller report P-bodies’ role in the control of translation in the Sept. 23 issue of the journal Cell. Coller, who did the research while at UA as a postdoctoral fellow with the Howard Hughes Medical Institute, is now an assistant professor in the Center for RNA Molecular Biology at Case Western Reserve University in Cleveland, Ohio.

The Parker lab’s findings about P-bodies serving as storage depots was released online Sept. 1, 2005 and will be published in an upcoming issue of Science. Complete citations for the two papers can be found at the end of this release. The Howard Hughes Medical Institute and the National Institutes of Health funded the research.

To live and grow, cells convert the genetic instructions stored in DNA into proteins. However, only some of the myriad instructions stored in genes are useful at any one time. Researchers want to figure out how cells switch from manufacturing one type of protein to another. mRNA molecules are key in the manufacturing process because they carry the protein-assembly instructions from the DNA to the assembly plant.

Although P-bodies were initially identified as just garbage dumps for used mRNA, Parker and his colleagues suspected P-bodies played a more important role in determining which proteins a cell makes.

The researchers investigated whether two proteins known to decommission mRNA, Dhh1p and Pat1p, were involved in regulating the translation of mRNA’s instructions into proteins. The scientists did their experiments with common baker’s yeast, a one-celled organism known to scientists as Saccharomyces cerevisiae.

To see what happened if the cellular machinery didn’t work right, the researchers compared the behavior of mutant yeast cells to normal yeast cells.

Coller and Parker tested mutant cells that lacked one or both proteins to see how they compared with normal cells. Under the microscope, only 10 percent of the mutant cells that lacked both proteins had P-bodies, whereas almost all the normal cells had P-bodies. In addition, the mutant cells could no longer turn off the use of mRNAs under the appropriate conditions. Parker said, "Cells missing these proteins could no longer turn off mRNAs and could no longer make P-bodies."

The team then engineered yeast cells to produce an overabundance of the proteins and repeated the experiments with those cells. Those cells stopped growing. Parker said, "The mRNAs are all driven away from the assembly factories. When you look through the microscope, the cells have huge P-bodies. It’s very dramatic."

Overabundance of a human protein similar to Dhh1p occurs in many tumors, but the function of the protein is unknown, Parker said. In another experiment, the team put some mRNA, some protein-assembly plants and some of the human protein, referred to as RCK, into test tubes.

When RCK was added, mRNAs did not enter the assembly plants, suggesting that the human protein prevents cells from translating mRNA’s instructions into the proteins that cells need to thrive. "Adding this protein would screw it up," Parker said. "The protein suppresses the translation process."

People initially thought that switching from making one protein to another happened solely by blocking the assembly of the protein-making machinery. Coller and Parker’s Cell paper shows that the regulation occurs by determining whether or not mRNA will enter the assembly plant or be shipped to a storage depot. Contrary to previous beliefs, the team suspects the cell can bypass the assembly plant altogether and send unneeded mRNAs straight to P-bodies to be degraded or eventually recycled.

Parker said his lab’s next step is examining the potential role of P-bodies in memory and in viral infections.

Mari N. Jensen | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>