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 The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie

nachricht How protein islands form
15.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>