Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How cells know which way to go

27.10.2014

Amoebas aren't the only cells that crawl: Movement is crucial to development, wound healing and immune response in animals, not to mention cancer metastasis. In two new studies from Johns Hopkins, researchers answer long-standing questions about how complex cells sense the chemical trails that show them where to go — and the role of cells' internal "skeleton" in responding to those cues.

In following these chemical trails, cells steer based on minute differences in concentrations of chemicals between one end of the cell and the other. "Cells can detect differences in concentration as low as 2 percent," says Peter Devreotes, Ph.D., director of the Department of Cell Biology at the Johns Hopkins University School of Medicine. "They're also versatile, detecting small differences whether the background concentration is very high, very low or somewhere in between."


In this video, lab-grown human leukemia cells move toward a pipette tip holding an attractive chemical.

Credit: Yulia Artemenko/Johns Hopkins Medicine

Working with Pablo Iglesias, Ph.D., a professor of electrical and computer engineering at Johns Hopkins, Devreotes' research group members Chuan-Hsiang Huang, Ph.D., a research associate, and postdoctoral fellow Ming Tang, Ph.D., devised a system for watching the response of a cellular control center that directs movement. They then subjected amoebas and human white blood cells to various gradients and analyzed what happened.

"Detecting gradients turns out to be a two-step process," says Huang. "First, the cell tunes out the background noise, and the side of the cell that is getting less of the chemical signal just stops responding to it. Then, the control center inside the cell ramps up its response to the message it's getting from the other side of the cell and starts the cell moving toward that signal." The results appear on the Nature Communications website on Oct. 27.

But to get going, the cell has to have first arranged its innards so that it's not just a uniform blob but has a distinct front and back, according to another study from Devreotes' group. In that work, visiting scientist Mingjie Wang, Ph.D., and postdoctoral fellow Yulia Artemenko, Ph.D., tested the role of so-called polarity — differences in sensitivity to chemicals between the front and back of a cell — in responding to a gradient.

"In previous studies, researchers added a drug that totally dismantled the cells' skeleton and therefore eliminated movement. They found that these cells had also lost polarity," Artemenko says. "We wanted to know whether polarity depended on movement and how polarity itself — independent of the ability to move — helped to detect gradients."

The team used a pharmaceutical cocktail that, rather than dismantling the cells' skeleton, froze it in place. Then, as in Huang's experiments, they watched the response of the cellular control center to chemical gradients. "Even though the cells couldn't remodel their skeleton in order to move, they did pick up signals from the gradients, and the response to the gradient was influenced by the frozen skeleton," Artemenko says. "This doesn't happen if the skeleton is completely gone, so now we know that the skeleton itself, not its ability to remodel, influences the detection of gradients." The results appear in the Nov. 6 issue of Cell Reports.

By fleshing out the details of how cells move, the results may ultimately shed light on the many crucial processes that depend on such movement, including development, immune response, wound healing and organ regeneration, and may provide ways to battle cancer metastasis.

###

Other authors on the Cell Reports paper are Wenjie Cai and Pablo Iglesias of The Johns Hopkins University. The study was funded by the National Institute of General Medical Sciences (grant numbers GM28007 and GM34933) and the National Natural Science Foundation of China (grant numbers 81000045 and 81000939).

Other authors on the Nature Communications paper are Mingjie Wang and Changji Shi of The Johns Hopkins University. The work was supported by the National Institute of General Medical Sciences (grant numbers GM28007, GM34933 and GM71920) and a Harold L. Plotnick Fellowship from the Damon Runyon Cancer Research Foundation.

Related stories:

Peter Devreotes on cell movement: http://www.hopkinsmedicine.org/institute_basic_biomedical_sciences/about_us/scientists/peter_devreotes.html

'Random' Cell Movement Is Directed from Within: http://www.hopkinsmedicine.org/news/media/releases/randon_cell_movement_is_directed_from_within

Shawna Williams | Eurek Alert!
Further information:
http://www.jhmi.edu

More articles from Life Sciences:

nachricht Seeing on the Quick: New Insights into Active Vision in the Brain
15.08.2018 | Eberhard Karls Universität Tübingen

nachricht New Approach to Treating Chronic Itch
15.08.2018 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Unraveling the nature of 'whistlers' from space in the lab

15.08.2018 | Physics and Astronomy

Diving robots find Antarctic winter seas exhale surprising amounts of carbon dioxide

15.08.2018 | Earth Sciences

Early opaque universe linked to galaxy scarcity

15.08.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>