Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Muscle cells self-destruct rather than grow with use

01.09.2006
Muscle cells that should grow stronger with use instead self-destruct when a protein called BAG3 isn’t around, researchers have shown.

Mice missing BAG3 seem fine at birth, but when they start using their muscles to breathe and stand, muscle cells rapidly degenerate and cannot regenerate, says Dr. Shinichi Takayama, cell and molecular biologist at the Medical College of Georgia.

The finding illustrates BAG3’s importance in maintaining mature skeletal muscle, researchers say in the September issue of the American Journal of Pathology.

They hope it will lead to prevention of muscle atrophy that characterizes diseases such as muscular dystrophy, heart failure and a lesser-known condition called myofibril myopathy, which affects the tiniest muscle fibers. Dr. Takayama believes his BAG3 knockout is a model for the worst case of this rare disease.

... more about:
»BAG3 »Takayama »Z-disc

“Basically we think that the degeneration starts because of usage of muscles, which should make them stronger,” Dr. Takayama says. Instead, cells previously dormant in utero start dying. “They cannot breathe, they cannot use their muscles and they die quickly,” he says of BAG3 knockout mice.

“When a muscle contraction happens, cytoskeletal degeneration occurs naturally,” he says. Interestingly, degeneration normally stimulates regeneration, but not in these mice. Instead cells take another option: when they can’t be fixed, they kill themselves.

This mass suicide in the absence of BAG3 is not a huge surprise. Dr. Takayama, the first to clone five members of the BAG family, says the proteins help regulate heat shock protein 70, which helps other proteins fold and function properly. The BAG family also has an anti-death function called antiapoptosis. Dr. Takayama is still dissecting the relationship between the anti-death function and BAG’s regulatory role with the heat shock protein. “If protein folding is not happening to a cell, that cell should die, so I think the two functions are related,” he says.

Without BAG3, researchers believe something goes wrong in the supporting structure of Z-discs, which help muscles contract. “The structure is tightly regulated by cytoskeletal proteins and something is wrong in the cytoskeleton of these mice,” he says. They found evidence of changes in the Z-discs that predate cell death, leading them to postulate that BAG3 is required for maintaining the integrity of Z-discs and other supporting components of the muscle cytoskeleton that helps strengthen and organize cells. “The muscle, in structure, seems normal at birth,” Dr. Takayama says. “But after four days, their Z-disc structure is disrupted.” Myofibrils, thin, cylindrical filaments that run the length of muscle cells, then begin to degenerate.

He first cloned BAG1 as an antiapoptotic protein more than 10 years ago while looking for a way to kill cancer cells. “BAG is one of the things that helps cancer cells survive,” says Dr. Takayama. In fact, BAG3 is highly expressed in cancer cells.

Last year, his group’s work published in Nature Neuroscience showed a BAG1 knockout experiences massive brain cell death as an embryo. He’s working on a mouse that over expresses BAG in muscle only, saying that should prevent cell death and atrophy.

The research was funded by the National Institutes of Health and the Muscular Dystrophy Association.

Toni Baker | EurekAlert!
Further information:
http://www.mcg.edu

Further reports about: BAG3 Takayama Z-disc

More articles from Life Sciences:

nachricht 'Y' a protein unicorn might matter in glaucoma
23.10.2017 | Georgia Institute of Technology

nachricht Microfluidics probe 'cholesterol' of the oil industry
23.10.2017 | Rice University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>