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 'Lipid asymmetry' plays key role in activating immune cells
20.02.2018 | Biophysical Society

nachricht New printing technique uses cells and molecules to recreate biological structures
20.02.2018 | Queen Mary University of London

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

'Lipid asymmetry' plays key role in activating immune cells

20.02.2018 | Life Sciences

MRI technique differentiates benign breast lesions from malignancies

20.02.2018 | Medical Engineering

Major discovery in controlling quantum states of single atoms

20.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>