Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How cells change the pace of their steps

07.08.2007
Scientists at UC San Diego have discovered how cells of higher organisms change the speed at which they move, a basic biological discovery that may help researchers devise ways to prevent cancer cells from spreading throughout the body.

The discovery reported by the UCSD scientists in Proceedings of the National Academy of Sciences (PNAS) and published Aug. 3 on the journal’s Web site describes forces and energy exerted by the cells as they traveled across an elastic substrate. In videos recorded as the cells moved, each looked like an irregularly shaped water balloon attached firmly on two sticky sections while periodically protruding in the forward direction and withdrawing from the trailing end.

In humans and other mammals, cell motility is essential for many physiological processes such as tissue renewal and the function of the immune system. Cell motility also is an essential part of embryonic development as fetal cells undergo an orchestrated migration to form functioning tissues and organs. Poorly regulated cell motility during embryonic development may result in some neurological diseases and birth defects such as cleft palate of the mouth. UCSD’s new findings may eventually be used to better understand and possibly treat such conditions and suggest possible new cancer treatments aimed at inhibiting the metastatic spreading of some cancer tumors.

Cells of all higher, or eukaryotic, species move in response to external stimuli. This movement is made possible by a series of inter-related biochemical reactions, some of which remodel the internal skeleton and others that add and remove adhesion points at strategic positions on the outer membrane. Regardless of their size or shape, cells use what cell biologists call the cell motility cycle to take one step per cycle: first, the cell extends its leading margin over the substratum forming a pseudopod or “foot-like” extension; secondly, the tip of the pseudopod develops an adhesion point that attaches to the substratum; next, the cell uses the new point of anchorage to contract; and finally, the trailing adhesion point detaches and the rear part of the cell retracts forward. The process repeats every 1 to 4 minutes in Dictyostelium cells, but the period of the cycle and the length of each step can be shorter or longer in other types of eukaryotic cells.

... more about:
»Dictyostelium »Lasheras »adhesion »motility

The scientists discovered that the crawling speed of Dictyostelium is not controlled by the sticking strength of the adhesion points, but rather by the frequency of the cell’s motility cycle or how often they take a new step.

“For the first time, we’ve been able to make precise measurements of the repetitive nature of the forces and strain energies exerted by cells, and this has allowed us to better characterize the mechanics of the cell motility cycle,” said Juan C. Lasheras, a co-author of the study and a professor of mechanical and aerospace engineering at UCSD’s Jacobs School of Engineering.

A cell can assume a variety of shapes due to its internal “cytoskeleton,” a network of crisscrossed protein fibers that forms an internal skeleton in a cell. The cytoskeleton is also involved in cell motility through its attachments to discrete adhesion regions on the cell membrane. As the cell moves, individual fibers can elongate at one end and shorten at the other.

“What has been lacking in the field is the ability to effectively measure and quantify the mechanical forces that cells use to move,” said Richard Firtel, a professor of cell and developmental biology in UCSD’s Division of Biological Sciences who co-directed the motility study with Lasheras. “Our study not only makes a major advance in understanding this key concept in biology, but also provides new tools that will allow us to make even more significant advances in the future. By using a model experimental cell such as Dictyostelium, we are able to design mutant strains that will permit us to dissect each component of the cell movement cycle, thus allowing us to understand the function of each biochemical part and how the whole system works in concert.”

As the Dictyostelium cells moved on the elastic substrate the researchers measured strain forces of as much as 1,000 times greater than the weight of the cell. “These forces are truly amazing,” said Lasheras. “It’s comparable to a 200-pound athlete repeatedly lifting a 200,000-pound barbell. These Dictyostelium cells constantly maintain their cytoskeleton under this strong tension, although they periodically increase and decrease the strength as part of the motility cycle. The faster cells could repeat the cycle, the faster they moved.”

The UCSD researchers examined a mutant strain of Dictyostelium that lacked an important cell adhesion protein called Talin, and to their surprise found that cells without Talin moved nearly as fast as wild-type cells. The finding suggests that the rate at which a cell can tighten and relax its cytoskeleton is more important in controlling its speed than how firmly it attaches to the substrate.

“Different cell types in the body can move at different speeds in response to many different stimuli, and while our collaborative study didn’t look at these possibilities per se, we were able for the first time to correlate the mechanical forces related to chemical changes occurring within cells,” said Firtel. “This study will help us understand the basis of a number of human genetics diseases and developmental abnormalities.”

The co-authors include Firtel, Lasheras, Fulbright fellow Juan C. del Alamo, research scientist Ruedi Meili, Ph.D. candidate Baldomero Alonso-Latorre and postdoctoral fellows Javier Rodriguez-Rodriguez and Alberto Aliseda. The research was supported by a grant from the National Institutes of Health.

Rex Graham | EurekAlert!
Further information:
http://www.ucsd.edu

Further reports about: Dictyostelium Lasheras adhesion motility

More articles from Life Sciences:

nachricht When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short
23.03.2017 | Institut für Pflanzenbiochemie

nachricht WPI team grows heart tissue on spinach leaves
23.03.2017 | Worcester Polytechnic Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short

23.03.2017 | Life Sciences

Researchers use light to remotely control curvature of plastics

23.03.2017 | Power and Electrical Engineering

Sea ice extent sinks to record lows at both poles

23.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>