Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > The forces of attraction: How cells change direction

Abstract:
Many cell types in higher organisms are capable of implementing directed motion in response to the presence of certain chemical attractants in their vicinity. A team led by Dr. Doris Heinrich of the Faculty of Physics and the Center for NanoScience (CeNS) at Ludwig-Maximilians-Universität (LMU) München has developed a novel technique to expose an ensemble of living cells to rapidly varying concentrations of chemoattractants.

The forces of attraction: How cells change direction

Germany | Posted on July 5th, 2011

"Using this novel experimental approach, we investigate with high temporal and spatial resolution how living cells react to rapid changes in concentration gradients of chemoattractants. This gives us a new means of studying how such changes are detected and transduced by the cell's signaling pathways," says Heinrich.

The work is also of clinical significance, since directed migration of cells is essential for embryonic development and for immune responses. The researchers have even used their system to build a chemotactic trap that allows them to immobilize cells by exposing them to rapidly changing patterns of chemoattractants. The term "chemotaxis" refers to the ability of many cell types in higher organisms to detect and respond to concentration gradients of specific compounds by migrating toward or away from the source of the gradient.

"We investigate how cells follow concentration gradients of a chemoattractant and change their migration direction after a change in the external stimulus. We have developed a so-called microfluidic gradient generator, which allows us to rapidly alter the direction of the gradient such that the cells are repeatedly stimulated to reverse their direction of migration," says Börn Meier, who is the first author on the new study.

Each cell migrates along a gradient by crawling in the direction of the source of a chemoattractant. This cell locomotion is in turn based on the ongoing reorganization of the cytoskeleton, a network of fibers made up of the protein actin within the living cell. In response to the presence of a chemoattractant, actin filaments are assembled at the front of the cell, causing the membrane to extend protrusions called pseudopodia in the direction of migration.

Previous studies have shown that this reorganization is controlled by the localized accumulation of signal molecules in response to the binding of the chemoattractant to specific receptors on the cell surface. "It is however very difficult to detect the underlying changes in the spatial and temporal distributions of the biochemical agents involved. In order to achieve this, very precise control over the shape and the direction of the chemoattractant gradient must be obtained," says Heinrich.

The new gradient generator provides this control, and promises to facilitate deeper insight into the signal pathways that control chemotaxis. In the new study, the investigators describe two different ways in which cells can reorient in response to changes in the gradient. Depending on the conditions, cells can either execute a U-turn, or they can go into reverse by disassembling the actin cytoskeleton at the prior leading edge of the cell, and switching the site of filament formation to the opposite end. Such reorganization of the actin cytoskeleton requires the participation of a large number of proteins.

The research team is especially interested in determining the spatio-temporally changing distributions of these factors during the course of the entire process. The new technique even makes it possible to vary the direction of the gradient field at such a high rate that, although the cell can respond to each switch by activating its internal signaling machinery, it does not have time to reorient the actin network appropriately before the gradient changes again. The net result is that the cell remains in its initial position, immobilized in a chemotactic trap.

In a further experiment cells were exposed to varying gradients of chemoattractant in the presence of drugs that are known to affect the chemotactic signal cascades in the cells. The team was able to show that one particular inhibitor has a drastic effect on the pattern of cell motion. As Heinrich emphasizes, "Our experimental setup will give us new insights into complex intracellular signalling pathways of fundamental relevance for many areas of biological research, including cell and developmental biology, biochemistry and medicine."

# Full bibliographic informationChemotactic cell trapping in controlled alternating gradient fields. B. Meier, A. Zielinski, C. Weber, D. Arcizet, S. Youssef, T. Franosch, J. O. Rädler, D. Heinrich. PNAS Early Edition 27 June 2011, doi: 10.1073/pnas.1014853108

####

For more information, please click here

Contacts:
Dr. Doris Heinrich
Faculty of Physics
Phone: +49 89 2180 6760
Fax: + 4989 2180 3182


Börn Meier Faculty of Physics
Phone: +49 89 2180 1453
Fax: +49 89 2180 3182

Copyright © AlphaGalileo

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

The International Space Elevator Consortium (ISEC) is proud to announce the 2014 Space Elevator Conference! This annual event will be held at the Museum of Flight in Seattle, Washington from Friday, August 22nd through Sunday, August 24th August 19th, 2014

KaSAM-2014 International Conference (September 7-10, 2014, Kathmandu, Nepal) August 19th, 2014

Success in Intracellular Imaging of Cesium Distribution in Plants Used for Cesium Absorption August 19th, 2014

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Chemistry

Production of Toxic Ion Nanosorbents with High Sorption Capacity in Iran August 17th, 2014

Scientists fold RNA origami from a single strand: RNA origami is a new method for organizing molecules on the nanoscale. Using just a single strand of RNA, this technique can produce many complicated shapes. August 14th, 2014

Could hemp nanosheets topple graphene for making the ideal supercapacitor? August 12th, 2014

Iranians Find Novel Method for Processing Highly Pure Ceramic Nanoparticles August 12th, 2014

Nanomedicine

Graphene rubber bands could stretch limits of current healthcare, new research finds August 19th, 2014

Interaction between Drug, DNA for Designing Anticancer Drugs Studied in Iran August 17th, 2014

Scientists fold RNA origami from a single strand: RNA origami is a new method for organizing molecules on the nanoscale. Using just a single strand of RNA, this technique can produce many complicated shapes. August 14th, 2014

Iranian Scientists Stabilize Protein on Highly Stable Electrode Surface August 14th, 2014

Discoveries

Success in Intracellular Imaging of Cesium Distribution in Plants Used for Cesium Absorption August 19th, 2014

Сalculations with Nanoscale Smart Particles August 19th, 2014

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Graphene rubber bands could stretch limits of current healthcare, new research finds August 19th, 2014

Announcements

Сalculations with Nanoscale Smart Particles August 19th, 2014

Life on Mars? Implications of a newly discovered mineral-rich structure August 19th, 2014

Harris & Harris Group Letter to Shareholders on Website August 19th, 2014

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE