Featured Research

from universities, journals, and other organizations

Muscle Cells Self-destruct Rather Than Grow With Use

Date:
September 19, 2006
Source:
Medical College of Georgia
Summary:
Muscle cells that should grow stronger with use instead self-destruct when a protein called BAG3 isn't around, researchers have shown.

Dr. Shinichi Takayama. (Phil Jones photo)

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.

“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.


Story Source:

The above story is based on materials provided by Medical College of Georgia. Note: Materials may be edited for content and length.


Cite This Page:

Medical College of Georgia. "Muscle Cells Self-destruct Rather Than Grow With Use." ScienceDaily. ScienceDaily, 19 September 2006. <www.sciencedaily.com/releases/2006/08/060830214612.htm>.
Medical College of Georgia. (2006, September 19). Muscle Cells Self-destruct Rather Than Grow With Use. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2006/08/060830214612.htm
Medical College of Georgia. "Muscle Cells Self-destruct Rather Than Grow With Use." ScienceDaily. www.sciencedaily.com/releases/2006/08/060830214612.htm (accessed October 22, 2014).

Share This



More Health & Medicine News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

CDC Revamps Ebola Guidelines After Criticism

CDC Revamps Ebola Guidelines After Criticism

Newsy (Oct. 21, 2014) The Centers for Disease Control and Prevention have issued new protocols for healthcare workers interacting with Ebola patients. Video provided by Newsy
Powered by NewsLook.com
WHO: Ebola Vaccine Trials to Start a in January

WHO: Ebola Vaccine Trials to Start a in January

AP (Oct. 21, 2014) Tens of thousands of doses of experimental Ebola vaccines could be available for "real-world" testing in West Africa as soon as January as long as they are deemed safe in soon to start trials, the World Health Organization said Tuesday. (Oct. 21) Video provided by AP
Powered by NewsLook.com
First-Of-Its-Kind Treatment Gives Man Ability To Walk Again

First-Of-Its-Kind Treatment Gives Man Ability To Walk Again

Newsy (Oct. 21, 2014) A medical team has for the first time given a man the ability to walk again after transplanting cells from his brain onto his severed spinal cord. Video provided by Newsy
Powered by NewsLook.com
CDC Issues New Ebola Guidelines for Health Workers

CDC Issues New Ebola Guidelines for Health Workers

Reuters - US Online Video (Oct. 21, 2014) The U.S. Centers for Disease Control and Prevention has set up new guidelines for health workers taking care of patients infected with Ebola. Linda So reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins