Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

One taste of growth protein and nerve cells want more

26.07.2004


Johns Hopkins researchers report that once a growing nerve "tastes" a certain protein, it loses its "appetite" for other proteins and follows the tasty crumbs to reach its final destination. The finding in mice, reported in the July 23 issue of Cell, appears to help explain how nerves connect to their targets and stop growing once there, a process important for the normal development of mouse and man.



During prenatal development, a nerve connects to its proper targets in part by obeying protein signals sampled en route. If the signals aren’t right or aren’t found, the growing nerve can connect to the wrong organ or not connect at all.

In experiments on mice, the Hopkins scientists learned that a protein called NT-3 (neurotrophin-3), produced and distributed at the halfway point, and one called NGF (nerve growth factor), which is expressed at the target organ, both attract the growing ends of a certain type of nerve cell. However, the Hopkins team found that only NGF can convince the nerve that it "tastes better," an ability that allows the nerve to leave the halfway point, grow to the source of NGF and then stay put.


"It seems incredible that a nerve finds its target this way during development, but we have a new glimpse into exactly how it happens," says David Ginty, Ph.D., associate professor in the Department of Neuroscience of Hopkins’ Institute for Basic Biomedical Sciences and a Howard Hughes Medical Institute investigator. "We have found that the growth of some nerves is controlled by target-derived cues, which are proteins that chemically change the nerves so that they are enticed to leave intermediate targets for final targets."

Scientists have long known that mammals, including mice and humans, normally grow more nerve cells than are needed during development, and that those that don’t successfully connect die off. Nerve cells have a long way to travel, and they are attracted to a number of intermediate sites along the way. But scientists haven’t understood exactly how the nerve endings move on.

Using mice engineered to lack either NT-3 or NGF, the Hopkins scientists, led by postdoctoral fellow Rejji Kuruvilla, Ph.D., and graduate students Larry Zweifel and Natalia Glebova, examined the nerve connections to a number of internal organs, including the heart, small intestine, salivary glands and fat deposits.

In mice without NT-3, nerves failed to grow to intermediate targets. In contrast, nerves in mice lacking NGF stayed at the intermediate site; they failed to grow into the final targets. Therefore, it appears the nerves need to first taste NT-3 and then NGF to properly connect to their targets, the researchers say.

To discover why nerves prefer NGF even when they can taste NT-3, the scientists compared nerve growth in the genetically engineered mice to growth in normal mice. Through these experiments, the researchers discovered that after they taste NT-3 and follow it to the intermediate site, growing nerves detect and "swallow" a small amount of NGF, wafted from the final target.

The key to the nerves’ preference, however, is what happens next. The NGF then is transported to the nerve cell’s command center, where it causes production of another protein. This protein, p75, moves back to the nerve’s growing tip and makes it impossible for NT-3 to act. Now less sensitive to NT-3, the nerve’s tip snakes through clouds of increasing amounts of NGF toward the organ producing the NGF. Once there, it stops.

"We were pleasantly surprised to discover that the ultimate target expresses a protein that physically changes the approaching nerve cell and makes other growth protein ’competitors’ seem less appealing," says Ginty. "We suspect that other nerve cells may be manipulated in a similar fashion by a different series of proteins. We’ll be studying that next."

Joanna Downer | EurekAlert!
Further information:
http://www.jhmi.edu

More articles from Life Sciences:

nachricht Hidden dynamics detected in neuronal networks
23.07.2019 | Forschungszentrum Juelich

nachricht Towards a light driven molecular assembler
23.07.2019 | Christian-Albrechts-Universität zu Kiel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: MOF@SAW: Nanoquakes and molecular sponges for weighing and separating tiny masses

Augsburg chemists and physicists report how they have succeeded in the extremely difficult separation of hydrogen and deuterium in a gas mixture.

Thanks to the Surface Acoustic Wave (SAW) technology developed here and already widely used, the University of Augsburg is internationally recognized as the...

Im Focus: Better thermal conductivity by adjusting the arrangement of atoms

Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.

In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...

Im Focus: First-ever visualizations of electrical gating effects on electronic structure

Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.

Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...

Im Focus: Megakaryocytes act as „bouncers“ restraining cell migration in the bone marrow

Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.

Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

 
Latest News

Hidden dynamics detected in neuronal networks

23.07.2019 | Life Sciences

Towards a light driven molecular assembler

23.07.2019 | Life Sciences

A torque on conventional magnetic wisdom

23.07.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>