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 Complete skin regeneration system of fish unraveled
24.04.2018 | Tokyo Institute of Technology

nachricht Scientists generate an atlas of the human genome using stem cells
24.04.2018 | The Hebrew University of Jerusalem

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Complete skin regeneration system of fish unraveled

24.04.2018 | Life Sciences

Scientists create innovative new 'green' concrete using graphene

24.04.2018 | Materials Sciences

BAM@Hannover Messe: innovative 3D printing method for space flight

24.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>