Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bursts of waves drive immune system 'soldiers' toward invaders

14.08.2007
Scientists have discovered that torrents of microscopic waves propel white blood cells toward invading microbes. The discovery - recorded on videotape -- holds the potential for better understanding and treatment of cancer and heart disease.

Visible only under a very high-resolution light microscope, the dynamic waves are made of a signaling protein that directs cell movement. This protein and a second key player were already known to trigger cells to move, but their interaction to generate the self-sustaining waves has now been revealed.

"Seeing the wavelike dynamics of this protein, Hem-1, for the first time was easily the most instantly thrilling and illuminating finding in my scientific career," says Orion Weiner, PhD, of the University of California, San Francisco, who led the scientific team. "It immediately suggested how this protein might be organizing cell movement - an idea that our subsequent experiments validated.

"We never expected to see this sort of complex behavior within cells, but in retrospect it is an absolutely ingenious way to organize cell movement. We're getting our first glimpses that take us beyond knowing that this protein is important for cell motility to learning how it might organize the complex choreography of cell movement."

... more about:
»Cycle »Hem-1 »cell movement »circuit »generate »scientists

The videotape of the unsuspected action shows wave upon wave advancing like a series of exploding fireworks. The novel behavior can be viewed at cvri.ucsf.edu/~weiner.

The research findings are reported in the August 13, 2007 online edition of the journal "Public Library of Science (PLoS) Biology." Lead author is Weiner, who is assistant professor of biochemistry at UCSF.

Because the same kind of components scrutinized in the new research also drive cancer cell metastasis, the finding may lead to strategies to block cancer growth. Similarly, faulty regulation of white blood cell movement plays a role in heart attack - another promising target for applying the new insights of the regulation of cell movement, the authors say.

White blood cells, or neutrophils, are the body's first line of defense against potentially harmful microbes, and are one of the swiftest cells in the body. The wave action that speeds them along is generated by the same kind of three-part circuit that fires electrical signals along a neuron or prods the heart to beat, the researchers observe.

Videotaping allowed the scientists to watch as wave upon wave of the Hem-1 protein push neutrophils toward a chemical signal made by invading microbes. The researchers fluorescently tagged Hem-1 to view its dynamic propulsive power under the microscope.

Self-generating waves of Hem-1 control the pattern of assembly of building blocks of a second protein, actin. This protein physically contacts the cell membrane and prods it forward. But actin is not only an output of Hem-1 action; it also appears to eliminate the Hem-1 that has assembled it, the new research shows. The scientists think that this cycle of Hem-1 propulsion and annihilation is likely to produce the series of waves seen under the microscope.

The cell-propelling circuit contains a third component that makes it self-sustaining. The researchers found evidence that before each Hem-1 protein is eliminated, it recruits an additional Hem-1 right "next door." As each Hem-1 succumbs, a new one appears - but only on one side. Weiner thinks the structure of actin physically blocks Hem-1 from recruiting its daughter Hem-1 on one side, so Hem-1 is sequentially added only in one direction. This determines the direction of cell movement.

Weiner likens it to a Lego tower on its side. "If you kept adding blocks to one end and removing them from the other, you would have a moving tower that was the same size but kept adding new material. This is very similar to what is going on in a Hem-1 wave," he says.

The Hem-1 recruitment assures the cycle will continue. The cycle, or circuit, of activation, recruitment and inhibition, as it is called, can continue without "orders" from another part of the cell, the scientists report.

"One of the things that I find fascinating about these waves is how relatively simple patterns of protein interaction can generate very complex behaviors," says Weiner. "Evolution has found the same solution to generating waves again and again even with completely different molecules, and at different scales of space and time -- encouraging for those of us who want to uncover general organizing principles in biology."

Weiner is an investigator in both the UCSF Cardiovascular Research Institute and the California Institute for Quantitative Biosciences, or QB3, headquartered at UCSF.

Weiner initiated the research as a postdoctoral fellow in the lab of Marc Kirschner, PhD, professor and chair of systems biology at Harvard Medical School. Kirschner is a co-author on the paper.

The cycle the scientists studied is very similar in concept to the circuit that generates neuronal conduction, the beating of the heart, and many other waves in biology, according to Weiner.

"All of these use a self-activating signal that plants the seeds for its own destruction, even while it is progressing. This results in a wave that moves undiminished because of the self-activation, and in one direction, because of the inhibition it leaves in its wake," he says.

The scientists observed the Hem-1 activation of actin assembly and actin's inhibition of Hem-1 accumulation. The "recruitment" component was not directly observed, but is consistent with their observations and experiments.

In the research, the team used the fluorescently tagged Hem-1 to determine whether the protein participated in the wave action, or was the wave itself.

Using optical tricks to label specific pools of Hem-1, they found that molecules of Hem-1 don't move, but pass information between molecules to generate a wave.

The research is now focusing on how external signals influence this wave generator to guide the cells. They also want to learn if the wave action they have discovered in neutrophils also controls movement and shapes changes in other cells and organisms.

Wallace Ravven | EurekAlert!
Further information:
http://www.ucsf.edu

Further reports about: Cycle Hem-1 cell movement circuit generate scientists

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>