Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Derailing inner ear development

25.01.2010
A molecule that regulates expression of two growth factors is critical for inner ear development

During mammalian neural development, cells extend projections to target tissues from which they derive growth factors needed for survival. Initially, neurons of the inner ear require brain-derived neurotrophic factor (Bdnf) and neurotrophin 3 (Ntf3) from the otic placode, the sensory epithelium from which the cells are derived. Later, the cells express these growth factors themselves, which support the neurons that project to them.

Although this process is well known, the underlying molecular mechanisms have been unclear. Slitrk6, a transmembrane protein with structural similarities to the Slit family of axon guidance molecules and to the Ntrk neurotrophic factor receptors, is known to be expressed in the otic placode, and is therefore likely to play a role in inner ear development.

To investigate this, Kei-ichi Katayama of the RIKEN Brain Science Institute and his colleagues generated mice lacking the Slitrk6 gene. They found that the gross structure of the inner appeared normal1. However, they observed a significant reduction in the number of nerve fiber bundles projecting to the cochlea (Fig. 1). These defects were evident during late embryonic stages, and persisted throughout postnatal development. In the vestibular region, the defects were more severe, with nerve fibers bundles completely absent in this region in most mutant animals. In others, they were significantly reduced or had abnormal trajectories.

Next the researchers examined the spiral and vestibular ganglia, which contain neurons that project to the cochlea and vestibular region, respectively. Cell death was significantly higher in the mutants than in wild-type animals, so that the structures were up to 75% smaller than normal by the time of birth.

They also found that cultured sensory neurons from the spiral ganglion of mutant mice could grow projections towards sensory epithelial tissue from normal, but not mutant, mice. Further experiments revealed a mild but significant reduction in levels of Bdnf and Ntf-3 in the developing inner ear of the mutants. The phenotype of the mutant mice is therefore not due to axon guidance defects. Instead, these results suggest that Slitrk6 is part of a signaling pathway that increases expression of Bdnf and Ntf3 in the sensory epithelia.

“Behavioral tests show that the Slitrk6 knockout mice exhibit hearing loss,” says senior author Jun Aruga, “and we are now investigating whether they also have balance deficits. We believe our mutant mice are a good animal model of sensorineural deafness, which occurs because of improper cochlear development, following over-exposure to loud noises, and as a result of aging.”

The corresponding author for this highlight is based at the Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute

Saeko Okada | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6158
http://www.researchsea.com

Further reports about: Brain Derailing Ntf3 RIKEN inner ear molecular mechanism mutant mice nerve fiber

More articles from Health and Medicine:

nachricht Malaria Already Endemic in the Mediterranean by the Roman Period
27.07.2017 | Universität Zürich

nachricht Serious children’s infections also spreading in Switzerland
26.07.2017 | Universitätsspital Bern

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

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

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

Programming cells with computer-like logic

27.07.2017 | Life Sciences

Identified the component that allows a lethal bacteria to spread resistance to antibiotics

27.07.2017 | Life Sciences

Malaria Already Endemic in the Mediterranean by the Roman Period

27.07.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>