Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

High-speed images show how cells mobilize for immune response

17.04.2003


New high-speed imaging techniques are allowing scientists to show how a single cell mobilizes its resources to activate its immune response, a news research study shows.



Howard R. Petty, Ph.D., professor and biophysicist at the University of Michigan Health System’s Kellogg Eye Center, has dazzled his colleagues with movies of fluorescent-lit calcium waves that pulse through the cell, issuing an intracellular call-to-arms to attack the pathogens within.

He explains that these high-speed images provide a level of detail about cell signaling that simply wasn’t possible just a few years ago.


In the April 15 issue of the Proceedings of the National Academy of Sciences, Petty provides more detail on cell signaling, depicting what he calls the "molecular machinery" underlying the immune response. He has identified a sequence of amino acids (LTL) that controls the calcium wave pathway and, crucially, the ability of immune cells to destroy targets.

The findings are important because they could eventually lead scientists to design drugs based on the amino acid motif.

"Our clinical goal," explains Petty, "is to characterize the immune cell’s signaling function so that we can interrupt it or somehow intervene when it begins to misfire." The process has implications for treating autoimmune diseases such as arthritis, multiple sclerosis, and the eye disorder uveitis.

Through images of phagocytosis, the process by which a cell engulfs and then destroys its target, Petty is able to track the movement of calcium waves as they send signals to key players in the immune response. The "calcium wave" is a stream of calcium ions coming into the cell, which is detected by the fluorescence emission of a calcium-sensing dye.

As a cell membrane begins to surround its target, two calcium waves begin to circulate. When the target is completely surrounded, one wave traveling around the cell’s perimeter splits in two, with the second wave encircling the phagosome or sac-like compartment. This second wave allows the digestive enzymes to enter the phagosome and finally destroy the target.

When Petty introduced a mutation in the gene (FcyRIIA) that controls phagocytosis, he found that the calcium wave simply circled the cell and bypassed the phagosome altogether. As a result, the immune cell could engulf, but could not carry out the destruction of its target. This led him to conclude that the LTL sequence orchestrates the cell signaling process.

The sequence may also have a role in directing other cell activities, for example signaling the endoplasmic reticulum to form a spindle that connects the phagosome and the outer cell membrane. "The spindle seems to act as an extension cord that signals the calcium wave into the phagosome to finish the attack," suggests Petty.

Petty explains that many of these findings are possible thanks to high-speed imaging techniques that enable him to merge knowledge of physics with cell and molecular biology. He uses high sensitivity fluorescence imaging with shutter speeds 600,000 times faster than video frames.

"Before the advent of high-speed imaging, you could not ask many of these questions because we had no way to see the movement of calcium waves," he says. "With conventional imaging you ended up with a blur of calcium." By contrast, Petty’s images resemble the movement of a comet across the night sky.

In the study reported in PNAS, Petty used leucocytes as a model for the process. The amino acid sequence is in the region of the gene FcyRIIA. He is currently studying the same phenomena in the eye, where phagocytosis disposes of the regularly-shed remnants of photoreceptor cells.


The paper, Signal sequence within FcRIIA controls calcium wave propagation patterns: Apparent role in phagolysosome fusion, also appears on the PNAS internet site at www.pnas.org.

Betsy Nisbet | EurekAlert!
Further information:
http://www.pnas.org

More articles from Life Sciences:

nachricht Topologische Quantenchemie
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

nachricht Topological Quantum Chemistry
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

Ultrathin device harvests electricity from human motion

24.07.2017 | Power and Electrical Engineering

Scientists announce the quest for high-index materials

24.07.2017 | Materials Sciences

ADIR Project: Lasers Recover Valuable Materials

24.07.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>