Corporate Banner
Satellite Banner
Scientific Communities
Become a Member | Sign in
Home>News>This Article

Scientists Discover how Cells Distinguish Friend from Foe

Published: Wednesday, April 03, 2013
Last Updated: Wednesday, April 03, 2013
Bookmark and Share
Researchers at UC Davis have shown how the innate immune system distinguishes between dangerous pathogens and friendly microbes.

Like burglars entering a house, hostile bacteria give themselves away by breaking into cells. However, sensing proteins instantly detect the invasion, triggering an alarm that mobilizes the innate immune response. This new understanding of immunity could ultimately help researchers find new targets to treat inflammatory disorders. The paper was published in Nature on March 31.

The immune system has a number of difficult tasks, including differentiating between cells and microbes. However, the body, particularly the digestive tract, contains trillions of beneficial microbes, which must be distinguished from dangerous pathogens.

"We are colonized by microbes. In fact, there are more bacteria in the body than cells," said senior author Andreas Bäumler, professor and vice chair of research in the UC Davis Department of Medical Microbiogy and Immunology. "The immune system must not overreact to these beneficial microbes. On the other hand it must react viciously when a pathogen invades."

The key to distinguishing between pathogenic and beneficial bacteria are their differing goals. Ordinary digestive bacteria are content to colonize the gut, while their more virulent cousins must break into cells to survive. Salmonella achieves this by activating enzymes that rearrange the actin in a cell's cytoskeleton. Fortunately, cellular proteins sense the active enzymes, leading to a rapid immune response.

In the study, the researchers investigated a strain of Salmonella, in both cell lines and animal models, to determine how the innate immune system singles out the bacteria for attack. Salmonella uses a secretion system, a type of molecular syringe, to inject pathogenic proteins, such as SopE, into the cell. SopE activates human GTPase enzymes RAC1 and CDC42, which break down the surrounding actin, allowing the bacterium inside.

But breaking and entering has consequences. Sensing the active GTPase enzymes, and recognizing their pathogenic nature, a protein called NOD1 sends the alarm, signaling other proteins, such as RIP2, that the cell is in danger. Ultimately, this signaling pathway reaches the protein NF-κB, a transcription factor that instructs the genome to mount an immune response, activating genes associated with inflammation, neutrophils and other immune functions.

Though it had been hypothesized that GTPase activation might trigger an immune response to attacking bacteria, prior to this study, no one had identified the pathway to NF-κB. These results were somewhat surprising, as NOD1had been thoroughly studied; leading many researchers to conclude it had no further mysteries to divulge. No one expected it to play such a significant role in alerting the innate immune system that cells were under attack.

These results could help researchers find new targets to combat inflammatory diseases. For example, NF-κB is known to be involved in a variety of conditions, such as inflammatory bowel disease, arthritis, sepsis and others. By understanding the pathways that activate inflammation, scientists and clinicians can develop ways to inhibit it.

"These pathways might be triggered erroneously because the host thinks there's an infection," said Bäumler. "Knowing the pathways and how they are activated is critical to controlling them."

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,800+ scientific posters on ePosters
  • More Than 4,000+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

RNA-Based Drugs Give More Control Over Gene Editing
CRISPR/Cas9 gene editing technique can be transiently activated and inactivated using RNA-based drugs, giving researchers more precise control in correcting and inactivating genes.
Monday, November 23, 2015
Some 3-D Printed Objects Are Toxic
Researchers at the University of California, Riverside have found parts produced by some commercial 3-D printers are toxic to certain fish embryos.
Monday, November 09, 2015
Artificial Kidney Research Gets A Boost
Development of a surgically implantable, artificial kidney — a promising alternative to kidney transplantation or dialysis for people with end-stage kidney disease — has received a $6 million boost.
Monday, November 09, 2015
Clearest Ever Images of Enzyme that Plays Key Roles in Aging, Cancer
UCLA-led research on telomerase could lead to new strategies for treating disease
Monday, October 19, 2015
Crop Cure
Scientists in new center to use medical research techniques to help food crops withstand drought and climate change.
Friday, October 16, 2015
Rare Childhood Leukemia Reveals Surprising Genetic Secrets
A coalition of leukemia researchers led by scientists from UC San Francisco has discovered surprising genetic diversity in juvenile myelomonocytic leukemia (JMML), a rare but aggressive childhood blood cancer.
Thursday, October 15, 2015
Sustaining Our Salad
Improving lettuce crops is the aim of a new, $4.5 million grant, awarded to University of California, Davis, researchers by the U.S. Department of Agriculture's National Institute of Food and Agriculture.
Thursday, October 15, 2015
Double Enzyme Hit May Explain Common Cancer Drug Side Effect
Mouse study suggests genomic screening before treatment may help prevent anemia.
Wednesday, October 14, 2015
New Autism Genes Are Revealed in Largest-Ever Study
Work draws more detailed picture of genetic risk, sheds light on sex differences in diagnosis.
Wednesday, September 30, 2015
Influenza A Viruses More Likely To Emerge In East Asia Than North America
Novel strains of influenza A are more likely to emerge in East Asia than in North America, according to a global analysis by the One Health Institute at the UC Davis School of Veterinary Medicine and EcoHealth Alliance.
Wednesday, September 30, 2015
Opening the Door to Safer, More Precise Cancer Therapies
New method regulates when, and how strongly, cancer-killing therapeutic T cells are activated.
Tuesday, September 29, 2015
Crunching Numbers to Combat Cancer
UCSF receives $5 million to integrate data from cancer research models.
Wednesday, September 16, 2015
Virus In Cattle Linked To Human Breast Cancer
A new study by UC Berkeley researchers establishes for the first time a link between infection with the bovine leukemia virus and human breast cancer.
Wednesday, September 16, 2015
Ultrafast DNA Diagnostics
New technology developed by UC Berkeley bioengineers promises to make a workhorse lab tool cheaper, more portable and many times faster by accelerating the heating and cooling of genetic samples with the switch of a light.
Monday, August 03, 2015
Scientists Create CRISPR/Cas9 Knock-In Mutations in Human T Cells
In a project spearheaded by investigators at UC San Francisco, scientists have devised a new strategy to precisely modify human T cells using the genome-editing system known as CRISPR/Cas9.
Tuesday, July 28, 2015
Scientific News
High Throughput Mass Spectrometry-Based Screening Assay Trends
Dr John Comley provides an insight into HT MS-based screening with a focus on future user requirements and preferences.
Kitchen Utensils Can Spread Bacteria Between Foods
In a recent study researchers found that produce that contained bacteria would contaminate other produce items through the continued use of knives or graters—the bacteria would latch on to the utensils commonly found in consumers' homes and spread to the next item.
Exploring the Causes of Cancer
Queen's research to understand the regulation of a cell surface protein involved in cancer.
Safer, Faster Way To Remove Pollutants From Water
Using nanoparticles filled with enzymes proves more effective than current methods.
Drug May Prevent Life-Threatening Muscle Loss in Advanced Cancers
New data describes how an experimental drug can stop life-threatening muscle wasting (cachexia) associated with advanced cancers and restore muscle health.
Ancient Viral Molecules Essential for Human Development
Genetic material from ancient viral infections is critical to human development, according to researchers at the Stanford University School of Medicine.
Novel Tumor Treatment
In the first published results from a $386,000 National Cancer Institute grant awarded earlier this year, a paper by Scott Verbridge and Rafael Davalos has been published.
Speeding Up the Process of Making Vaccines
System uses a freeze-dry concept to develop "just-add-water" solution.
Chemical Design Made Easier
Rice University scientists prepare elusive organocatalysts for drug and fine chemical synthesis.
New Analysis Technique for Chiral Activity in Molecules
Professor Hyunwoo Kim of the Chemistry Department and his research team have developed a technique that can easily analyze the optical activity of charged compounds by using nuclear magnetic resonance (NMR) spectroscopy.
Scroll Up
Scroll Down
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,800+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
4,000+ scientific videos