Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Proteins Hey1 and Hey2 Ensure that Inner Ear 'Hair Cells' Are Made at the Right Time and in the Right Place

17.09.2014

Two Johns Hopkins neuroscientists have discovered the “molecular brakes” that time the generation of important cells in the inner ear cochleas of mice. These “hair cells” translate sound waves into electrical signals that are carried to the brain and are interpreted as sounds. If the arrangement of the cells is disordered, hearing is impaired. A summary of the research will be published in The Journal of Neuroscience on Sept. 16.

“The proteins Hey1 and Hey2 act as brakes to prevent hair cell generation until the time is right,” says Angelika Doetzlhofer, Ph.D., an assistant professor of neuroscience. “Without them, the hair cells end up disorganized and dysfunctional.”


Angelika Doetzlhofer

The hair cells of mice missing just Hey2 are neatly lined up in four rows (left) while those missing Hey1 and Hey2 are disorganized (right). The cells' hairlike protrusions (pink) can be misoriented, too.

The cochlea is a coiled, fluid-filled structure bordered by a flexible membrane that vibrates when sound waves hit it. This vibration is passed through the fluid in the cochlea and sensed by specialized hair cells that line the tissue in four precise rows. Their name comes from the cells’ hairlike protrusions that detect movement of the cochlear fluid and create electrical signals that relay the sound to the brain.

During development, “parent cells” within the cochlea gradually differentiate into hair cells in a precise sequence, starting with the cells at the base of the cochlea and progressing toward its tip. The signaling protein Sonic Hedgehog was known to be released by nearby nerve cells in a time- and space-dependent pattern that matches that of hair cell differentiation. But the mechanism of Sonic Hedgehog’s action was unclear.

Doetzlhofer and postdoctoral fellow Ana Benito Gonzalez bred mice whose inner ear cells were missing Hey1 and Hey2, two genes known to be active in the parent cells but turned off in hair cells. They found that, without those genes, the cells were generated too early and were abnormally patterned: Rows of hair cells were either too many or too few, and their hairlike protrusions were often deformed and pointing in the wrong direction.

“While these mice didn’t live long enough for us to test their hearing, we know from other studies that mice with disorganized hair cell patterns have serious hearing problems,” says Doetzlhofer.

Further experiments demonstrated the role of Sonic Hedgehog in regulating the two key genes.

“Hey1 and Hey2 stop the parent cells from turning into hair cells until the time is right,” explains Doetzlhofer. “Sonic Hedgehog applies those ‘brakes,’ then slowly releases pressure on them as the cochlea develops. If the brakes stop working, the hair cells are generated too early and end up misaligned.”

She adds that Sonic Hedgehog, Hey1 and Hey2 are found in many other parent cell types throughout the developing nervous system and may play similar roles in timing the generation of other cell types.

This work was supported by grants from the Whitehall Foundation (2010-05-81) and the National Institute on Deafness and other Communication Disorders (F32DC013477, DC005211).

On the Web:

View the article at The Journal of Neuroscience (after the embargo lifts). http://dx.doi.org/10.1523/JNEUROSCI.1494-14.2014

Learn more about Angelika Doetzlhofer.
www.hopkinsmedicine.org/profiles/results/directory/profile/6477655/angelika-doetzlhofer

Catherine Kolf | newswise

Further reports about: Cells Communication Disorders Medicine brakes cell types genes hair cells hearing sound waves

More articles from Life Sciences:

nachricht Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University

nachricht Researchers discover specific tumor environment that triggers cells to metastasize
22.11.2017 | University of California - San Diego

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

UCLA engineers use deep learning to reconstruct holograms and improve optical microscopy

22.11.2017 | Medical Engineering

Watching atoms move in hybrid perovskite crystals reveals clues to improving solar cells

22.11.2017 | Materials Sciences

New study points the way to therapy for rare cancer that targets the young

22.11.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>