Featured Research

from universities, journals, and other organizations

Cells have early-warning system for intruders

Date:
October 17, 2011
Source:
European Molecular Biology Laboratory (EMBL)
Summary:
When a thief breaks into a bank vault, sensors are activated and the alarm is raised. Cells have their own early-warning system for intruders, and scientists have discovered how a particular protein sounds that alarm when it detects invading viruses. The study is a key development in our understanding of the innate immune response, shedding light on how cells rapidly respond to a wide range of viruses including influenza, rabies and hepatitis.

Scientists have discovered how a particular protein sounds that alarm when it detects invading viruses.
Credit: EMBL/Cusack

When a thief breaks into a bank vault, sensors are activated and the alarm is raised. Cells have their own early-warning system for intruders, and scientists at the European Molecular Biology Laboratory (EMBL) in Grenoble, France, have discovered how a particular protein sounds that alarm when it detects invading viruses. The study, published October 14 in Cell, is a key development in our understanding of the innate immune response, shedding light on how cells rapidly respond to a wide range of viruses including influenza, rabies and hepatitis.

To sense invading agents, cells use proteins called pattern recognition receptors, which recognise and bind to molecular signatures carried only by the intruder. This binding causes the receptors to change shape, starting a chain-reaction that ultimately alerts the surrounding cells to the invasion. How these two processes - sensing and signalling -- are connected, has until now remained unclear. The EMBL scientists have now discovered the precise structural mechanism by which one of these receptors, RIG-I, converts a change of shape into a signal.

"For a structural biologist this is a classic question: how does ligand binding to a receptor induce signalling?" says Stephen Cusack, who led the work. "We were particularly interested in answering it for RIG-I, as it targets practically all RNA viruses, including influenza, measles and hepatitis C."

In response to a viral infection, RIG-I recognises viral genetic material -- specifically, viral RNA -- and primes the cell to produce the key anti-viral molecule, interferon. Interferon is secreted and picked up by surrounding cells, causing them to turn on hundreds of genes that act to combat the infection. To understand how RIG-I senses only viral RNA, and not the cell's own RNA, and sounds the alarm, the scientists used intense X-ray beams generated at the European Synchrotron Radiation Facility (ESRF) to determine the three-dimensional atomic structure of RIG-I in the presence and absence of viral RNA, in a technique called X-ray crystallography. They found that in the absence of a viral infection, the receptor is 'sleeping with one eye open': the part of RIG-I that senses viral RNA is exposed, whilst the domains responsible for signalling are hidden, out of reach of the signalling machinery. When RIG-I detects viral RNA, it changes shape, 'waking up' the signalling domains, which become accessible to trigger interferon production. Although the EMBL scientists used RIG-I from the mallard duck, this receptor's behaviour is identical to that of its human counterpart.

"RIG-I is activated in response to viral RNA, but a similar mechanism is likely to be used by a number of other immune receptors, whether they are specific to viruses or bacteria," says PhD student Eva Kowalinski, who carried out most of the work.

Thus, these findings contribute to a broader understanding of the workings of the innate immune system -- our first line of defence against intruders, and the subject of this year's Nobel Prize in Physiology or Medicine.


Story Source:

The above story is based on materials provided by European Molecular Biology Laboratory (EMBL). Note: Materials may be edited for content and length.


Journal Reference:

  1. Kowalinski, E., Lunardi, T., McCarthy, A.A., Louber, J., Brunel, J., Grigorov, B., Gerlier, D. & Cusack, S. Structural basis for the activation of innate immune pattern recognition receptor RIG-I by viral RNA. Cell, 14 October 2011 DOI: 10.1016/j.cell.2011.09.039

Cite This Page:

European Molecular Biology Laboratory (EMBL). "Cells have early-warning system for intruders." ScienceDaily. ScienceDaily, 17 October 2011. <www.sciencedaily.com/releases/2011/10/111014080026.htm>.
European Molecular Biology Laboratory (EMBL). (2011, October 17). Cells have early-warning system for intruders. ScienceDaily. Retrieved August 2, 2014 from www.sciencedaily.com/releases/2011/10/111014080026.htm
European Molecular Biology Laboratory (EMBL). "Cells have early-warning system for intruders." ScienceDaily. www.sciencedaily.com/releases/2011/10/111014080026.htm (accessed August 2, 2014).

Share This




More Plants & Animals News

Saturday, August 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Pyrenees Orphan Bear Cub Gets Brand New Home

Pyrenees Orphan Bear Cub Gets Brand New Home

AFP (Aug. 1, 2014) The discovery of a bear cub in the Pyrenees mountains made headlines in April 2014. Despire several attempts to find the animal's mother, the cub remained alone. Now, the Pyrenees Conservation Foundation has constructed an enclosure. Duration: 00:31 Video provided by AFP
Powered by NewsLook.com
Ebola Vaccine Might Be Coming, But Where's It Been?

Ebola Vaccine Might Be Coming, But Where's It Been?

Newsy (Aug. 1, 2014) Health officials are working to fast-track a vaccine — the West-African Ebola outbreak has killed more than 700. But why didn't we already have one? Video provided by Newsy
Powered by NewsLook.com
Study Links Certain Birth Control Pills To Breast Cancer

Study Links Certain Birth Control Pills To Breast Cancer

Newsy (Aug. 1, 2014) Previous studies have made the link between birth control and breast cancer, but the latest makes the link to high-estrogen oral contraceptives. Video provided by Newsy
Powered by NewsLook.com
Rare Whale Fossil Pulled from Calif. Backyard

Rare Whale Fossil Pulled from Calif. Backyard

AP (Aug. 1, 2014) A rare whale fossil has been pulled from a Southern California backyard. The 16- to 17-million-year-old baleen whale fossil is one of about 20 baleen whale fossils known to exist. (Aug. 1) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins