Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Age-related muscle loss linked to protein interplay, says Stanford researcher

28.11.2003


Any older athlete can attest that aging muscles don’t heal as fast as youthful ones. Now researchers at Stanford University School of Medicine have found a molecular link between older muscles and slow healing. This work could lead to ways of preventing atrophy from immobilization, space flight or simply due to aging.



"What you really want to do is maintain the youthfulness of the regeneration pathway," said Thomas Rando, MD, PhD, associate professor of neurology and neurological sciences and an investigator at the Veterans Affairs Palo Alto Health Care System. The work will be published in the Nov. 28 issue of Science.

Rando and postdoctoral scholar Irina Conboy, PhD, focused their attention on a group of cells called satellite cells, which dot the outside of muscle fibers. These cells come to the rescue of damaged muscles, dividing to form new muscle tissue and generating new satellite cells for future repairs.


In previous work, Rando found that satellite cells spring into action when a protein on the cell surface called Notch becomes activated, much like flicking the cell’s molecular "on" switch. What flips the switch is another protein called Delta, which is made on nearby cells in injured muscle. This same combination of Delta and Notch also plays a role in guiding cells through embryonic development.

Having found this pathway, Rando and Conboy wondered whether slow healing in older muscles resulted from problems with signaling between Delta and Notch - failing either to make enough Delta or to respond to the Delta signal.

In their initial experiments, Rando and Conboy found that young, middle-aged and older mice all had the same number of satellite cells in their muscles and that these cells contained equivalent amounts of Notch.

"It doesn’t seem as if there’s anything wrong with the satellite cells or Notch in aged muscle," Rando said. That left Delta as the suspect molecule.

To test whether older muscles produce normal amounts of Delta, the researchers looked at the amount of protein made by mice of different ages. Young and adult mice, equivalent to about 20- and 45-year-old humans, both had a large increase in Delta after an injury. Muscles in older mice, equivalent to a 70-year-old human, made much less Delta after an injury, giving a smaller cry for help to the satellite cells. In response, fewer satellite cells were activated to repair the muscle damage.

A further set of experiments showed that slow repair in older muscles can be overcome. When the team applied a molecule to young muscles that blocked Delta, those satellite cells failed to divide in response to damage. Conversely, when they applied a Delta-mimicking molecule to injured, older muscles, satellite cells began dividing much like the those in younger muscle. The older muscles with artificially activated satellite cells had a regenerative ability comparable to that of younger muscle.

Although the studies focused on muscle regeneration after injury, Rando said similar problems with the interplay between Delta and Notch may cause the gradual muscle atrophy that occurs in older people, in astronauts or in people whose limbs are immobilized in a cast or from bed rest.

"If you presume that normal muscle bulk is maintained by gradual replacement of muscle tissue by satellite cells and that gradual replacement is diminished in older people, that would lead to atrophy," Rando said. "Figuring out atrophy in one of the pathways could relate to the others."

Rando said his team still needs to learn what signals normally cause the muscle to produce Delta, why those signals fail in older muscles and whether that change is reversible.


Other Stanford researchers involved in the study are postdoctoral scholars Michael Conboy, PhD, and Gayle Smythe, PhD.

Stanford University Medical Center integrates research, medical education and patient care at its three institutions - Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children’s Hospital at Stanford. For more information, please visit the Web site of the medical center’s Office of Communication & Public Affairs at http://mednews.stanford.edu.

PRINT MEDIA CONTACT: Amy Adams at 650-723-3900 (amyadams@stanford.edu)
BROADCAST MEDIA CONTACT: M.A. Malone at 650-723-6912 (mamalone@stanford.edu)

Amy Adams | EurekAlert!
Further information:
http://mednews.stanford.edu

More articles from Health and Medicine:

nachricht NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures
17.11.2017 | National Institute of Standards and Technology (NIST)

nachricht High speed video recording precisely measures blood cell velocity
15.11.2017 | ITMO University

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: 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,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

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

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>