Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tension triggers muscle building - Scientists discover important mechanism for muscle building

14.03.2014

Skeletal muscles are built from small contractile units, the sarcomeres.

Many of these sarcomeres are connected in a well-ordered series to form myofibrils that span from one muscle end to the other. Contractions of these sarcomeres result in contraction of the entire muscle.


Are muscles (green) and tendons (red) under tension, sarcomeres form myofibrils and assemble like pearls on a chain (on the right in green). Picture: Manuela Weitkunat © MPI of Biochemistry

Scientists at the Max Planck Institute of Biochemistry (MPIB) in Munich-Martinsried recently identified a key mechanism how this muscle architecture is built during development.

“Mechanical tension is the essential trigger” explains Frank Schnorrer, group leader at the MPIB. “If tension is eliminated, no regular myofibrils, but only short, random protein assemblies can form. Such muscles are entirely non-functional”.

In order to move the body, skeletal muscles are pulling on the skeleton. For efficient muscle and skeletal movements it is essential that the muscle contracts only along a defined axis, for instance for the leg movement along the thigh. Such a directed contraction is achieved by the myofibrils that span through the entire length of the muscle.

At both ends, the myofibrils are anchored to the tendon cells, which themselves are linked to the skeleton. “Thereby, the entire force is transduced from the muscle to the skeleton,” Frank Schnorrer describes. How can the regular architecture of a many hundred sarcomeres long myofibril be built along a defined axis during muscle development?

PhD student Manuela Weitkunat and PostDoc Aynur Kaya-Çopur were investigating this question in the fruit fly Drosophila melanogaster. They discovered that shortly after the Drosophila flight muscles contact their tendons, mechanical tension is established.

This tension buildup occurs before sarcomeres are formed and reaches through the entire muscle-tendon-skeleton system. This tension axis equips the muscle with positional information along which the sarcomeres must form.

Absence of tension results in chaos

By using genetic mutations in the fly, the scientists of the Muscle Dynamics group have been able to block the attachment of flight muscles to tendons and thus eliminate tension formation in the system. As a consequence, muscles could not build long regular myofibrils anymore but instead distribute the sarcomeric protein complexes chaotically.

In order to directly test the influence of mechanical tension, the scientists used a laser to cut the tendons off the muscle. This strategy of tension release also led to a major defect in sarcomere and myofibril formation. “Based on these results, we are suggesting a new model of myofibril formation, which proposes tension dependent self-assembly of the sarcomeric components,” explains Frank Schnorrer.

“When a certain tension threshold is reached, myofibril formation is triggered. If tension is compromised, the sarcomeric components have no spatial information and assemble chaotically.”

As human muscles also contain myofibrils that are built by periodically arrayed sarcomeres, it is likely that a similar tension-based assembly model may also apply during human muscle development, so the scientists think. These results have now been published in the journal Current Biology.

Original Publication
M. Weitkunat, A. Kaya-Çopur, S.W. Grill and and F. Schnorrer: Tension and force-resistant attachment are essential for myofibrillogenesis in Drosophila flight muscle. Current Biology, March 13, 2014.
DOI: 10.1016/j.cub.2014.02.032

Contact
Dr. Frank Schnorrer
Muscle Dynamics
Max Planck Institute of Biochemistry
Am Klopferspitz 18
82152 Martinsried
Germany
E-Mail: schnorre@biochem.mpg.de
http://www.biochem.mpg.de/schnorrer

Anja Konschak
Public Relations
Max Planck Institute of Biochemistry
Am Klopferspitz 18
82152 Martinsried
Germany
Tel. +49 89 8578-2824
E-Mail: konschak@biochem.mpg.de
http://www.biochem.mpg.de

Weitere Informationen:

http://www.biochem.mpg.de/4137023/067_schnorrer_muskelentwicklung - complete press release
http://www.biochem.mpg.de/schnorrer - website of the Research Group "Muscle Dynamics" (Frank Schnorrer)

Anja Konschak | Max-Planck-Institut

Further reports about: Biochemistry Drosophila Max-Planck-Institut Tension built mechanism myofibril skeleton triggers

More articles from Life Sciences:

nachricht 'Lipid asymmetry' plays key role in activating immune cells
20.02.2018 | Biophysical Society

nachricht New printing technique uses cells and molecules to recreate biological structures
20.02.2018 | Queen Mary University of London

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

'Lipid asymmetry' plays key role in activating immune cells

20.02.2018 | Life Sciences

MRI technique differentiates benign breast lesions from malignancies

20.02.2018 | Medical Engineering

Major discovery in controlling quantum states of single atoms

20.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>