Featured Research

from universities, journals, and other organizations

Couch potato effect: Missing protein leaves mice unable to exercise

Date:
December 1, 2010
Source:
Sanford-Burnham Medical Research Institute
Summary:
Researchers have unveiled a surprising new model for studying muscle function: the couch potato mouse. While these mice maintain normal activity and body weight, they do not have the energy to exercise.

Mice without the protein PGC-1 develop normally but are unable to exercise. Obese humans are also deficient in PGC-1.
Credit: iStockphoto/James Brey

Daniel Kelly, M.D., and his colleagues at Sanford-Burnham Medical Research Institute (Sanford-Burnham) at Lake Nona have unveiled a surprising new model for studying muscle function: the couch potato mouse. While these mice maintain normal activity and body weight, they do not have the energy to exercise. In the December 1 issue of Cell Metabolism, Dr. Kelly's team reports what happens when muscle tissue lacks PGC-1, a protein coactivator that muscles need to convert fuel into energy.

"Part of our interest in understanding the factors that allow muscles to exercise is the knowledge that whatever this machinery is, it becomes inactive in obesity, aging, diabetes and other chronic conditions that affect mobility," Dr. Kelly explained.

Normally, physical stimulation boosts PGC-1 activity in muscle cells, which switches on genes that increase fuel storage, ultimately leading to "trained" muscle (the physical condition most people hope to attain through exercise). In obese individuals, PGC-1 levels drop, possibly further reducing a person's capacity to exercise -- creating a vicious cycle. In this study, mice without muscle PGC-1 looked normal and walked around without difficulty, but could not run on a treadmill.

This is the first time that PGC-1 has been completely removed from muscle tissue, providing researchers with a new model to unravel the protein's role in muscle development, exercise and metabolism. So what happens to mice with muscles short on PGC-1? Their mitochondria -- the part of the cell that converts fuel into energy -- can't function properly, so cells have to work harder to stay vigorous. This extra effort rapidly depletes carbohydrate fuel stores, leading to premature fatigue. In short, PGC-1 is necessary for exercise, but not normal muscle development and activity.

But these mice held another surprise. PGC-1-deficient couch potato mice were not obese and still respond normally to insulin -- meaning they are not at risk for developing diabetes despite their sedentary lifestyles and mitochondrial problems. This was unexpected because many scientists believe that dysfunctional mitochondria trigger a cascade of insulin resistance and diabetes. This study dispels that notion, instead suggesting that perhaps malfunctioning mitochondria are a result of diabetes, rather than a cause.

"Lo and behold, even though these animals couldn't run, they showed no evidence of insulin resistance," Dr. Kelly said. "We are now investigating what happens when we boost PGC-1 activity intermittently, as normally occurs when a person exercises."

This work was supported by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the National Heart, Lung and Blood Institute (NHLBI), institutes within the National Institutes of Health (NIH), and the American Diabetes Association.


Story Source:

The above story is based on materials provided by Sanford-Burnham Medical Research Institute. Note: Materials may be edited for content and length.


Journal Reference:

  1. Zechner C, Lai L, Fong JL, Geng T, Yan Z, Rumsey JW, Collia D, Chen Z, Wozniak DF, Leone TC, Kelly DP. Total skeletal muscle PGC-1 deficiency uncouples mitochondrial derangements from fiber type determination and insulin sensitivity. Cell Metabolism, December 1, 2010

Cite This Page:

Sanford-Burnham Medical Research Institute. "Couch potato effect: Missing protein leaves mice unable to exercise." ScienceDaily. ScienceDaily, 1 December 2010. <www.sciencedaily.com/releases/2010/11/101130122033.htm>.
Sanford-Burnham Medical Research Institute. (2010, December 1). Couch potato effect: Missing protein leaves mice unable to exercise. ScienceDaily. Retrieved October 1, 2014 from www.sciencedaily.com/releases/2010/11/101130122033.htm
Sanford-Burnham Medical Research Institute. "Couch potato effect: Missing protein leaves mice unable to exercise." ScienceDaily. www.sciencedaily.com/releases/2010/11/101130122033.htm (accessed October 1, 2014).

Share This



More Health & Medicine News

Wednesday, October 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Pregnancy Spacing Could Have Big Impact On Autism Risks

Pregnancy Spacing Could Have Big Impact On Autism Risks

Newsy (Oct. 1, 2014) A new study says children born less than one year and more than five years after a sibling can have an increased risk for autism. Video provided by Newsy
Powered by NewsLook.com
Robotic Hair Restoration

Robotic Hair Restoration

Ivanhoe (Oct. 1, 2014) A new robotic procedure is changing the way we transplant hair. The ARTAS robot leaves no linear scarring and provides more natural results. Video provided by Ivanhoe
Powered by NewsLook.com
Insertable Cardiac Monitor

Insertable Cardiac Monitor

Ivanhoe (Oct. 1, 2014) A heart monitor the size of a paperclip that can save your life. The “Reveal Linq” allows a doctor to monitor patients with A-Fib on a continuous basis for up to 3 years! Video provided by Ivanhoe
Powered by NewsLook.com
Attacking Superbugs

Attacking Superbugs

Ivanhoe (Oct. 1, 2014) Two weapons hospitals can use to attack superbugs. Scientists in Ireland created a new gel resistant to superbugs, and a robot that can disinfect a room in minutes. Video provided by Ivanhoe
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