Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

HIV accessory protein disables host immunity via receptor-protein intermediary

31.03.2006
Findings point to possible novel ways to fight AIDS, immune disorders, sepsis

Researchers at the University of Pennsylvania School of Medicine discovered that an HIV-1 accessory protein called Vpr destroys the host cell’s ability to survive by binding to a host receptor. This, in turn, keeps an important enzyme from activating the cell’s immune system. These findings refine an earlier understanding of Vpr HIV pathogenesis and imply new approaches to treating AIDS, inflammatory diseases such as rheumatoid arthritis, and possibly sepsis. This research appears in the February print issue of Nature Cell Biology.

Over a decade ago, Penn’s David Weiner, PhD, Associate Professor of Pathology and Laboratory Medicine, and colleagues reported that Vpr corrupted the glucocorticoid receptor (GR) pathway of the host cell. Vpr helps to usurp host-cell function by regulating cell differentiation, cell death, and suppressing host-cell immune response proteins. Weiner’s group found that Vpr binds to the glucocorticoid receptor, but it remained unclear whether the GR pathway was required for Vpr to commandeer the host cell’s machinery.

"We started to realize a few years ago that no one had asked the real question: Is the glucocorticoid receptor necessary for Vpr’s effects on the host cell?" recalls Weiner. To answer this question, the researchers used an siRNA, a short sequence of RNA used to silence gene expression, to completely destroy expression of the glucocorticoid receptor protein.

When the researchers kept the glucocorticoid receptor protein from being made, Vpr did not kill host cells. "This indicated that glucocorticoid receptor function is not what’s really necessary for Vpr activity," says Weiner. "The glucocorticoid receptor-Vpr complex must be interacting with something else."

The team, led by first author Muthumani Karuppiah, PhD, Senior Research Investigator, looked for molecules with which the glucocorticoid receptor-Vpr complex would bind and identified PARP-1, another protein that controls the action of NF-kB, a major immune regulator in the host cell. To verify their idea, the researchers used a mouse model in which PARP-1 was knocked out and found that their cells were immune to sepsis (pathogens and their toxins in the blood), because the NF-kB molecules did not go into overdrive, kicking up inflammatory molecules called cytokines. This data demonstrate that Vpr attacks PARP-1 activity, so the mice are immune to toxins created by pathogens – one indication that their immune surveillance has been compromised.

Using biochemistry tests, the researchers were able to show that Vpr does interact with PARP-1 through the glucocorticoid receptor. Vpr hitches a ride on the glucocorticoid receptor, driving glucocorticoid to bind to PARP-1– which, in turn, inactivates it. "Ultimately, glucocorticoid is really an intermediary between Vpr and PARP-1," explains Weiner.

Weiner cites several potential clinical implications of this basic research. These findings show an immune function that had not been previously attributed to the glucocorticoid receptor. "With additional study this research may provide approaches for designing new drugs to fight AIDS, as well as for inflammatory disorders," suggests Weiner. "This research also gives us a new way to think about the relationship between immune activation and sepsis, and it may have implications ultimately for our understanding of novel approaches to prevent sepsis."

Karen Kreeger | EurekAlert!
Further information:
http://www.uphs.upenn.edu

More articles from Life Sciences:

nachricht Individual Receptors Caught at Work
19.10.2017 | Julius-Maximilians-Universität Würzburg

nachricht Rapid environmental change makes species more vulnerable to extinction
19.10.2017 | 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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>