Scavenger cells repair muscle fibers

October 05, 2016

Everybody knows the burning sensation in the legs when climbing down a steep slope for a long time. It is caused by microruptures in the cell membrane of our muscle fibers. These holes in the cell envelopes must be closed as soon as possible as otherwise muscle cells will die off. Researchers at KIT were able to observe this repair process using high-resolution real-time microscopy. It only takes a few seconds until proteins from the inside of the injured cell form a repair patch that finally closes the hole in the membrane. The researchers at KIT now demonstrated that scavenger cells moving around within the muscle virtually perform nano-surgery to remove this repair patch later and restore the normal cell membrane structure. (DOI: 10.1038/NCOMMS12875)

The cells of our skeletal muscles have effective mechanisms for the repair of ruptures in their cell membranes. These ruptures are due to mechanical stress to which we expose our muscles even when doing healthy exercises. The cell membrane is an important barrier which is essential to the proper functioning and survival of cells. If this barrier collapses and cannot be repaired quickly, the muscle cell will die, resulting in a loss of muscle mass. People whose repair proteins, e.g. dysferlin, do not work properly develop atrophy of the muscles which leads to most severe disabilities and premature death.

In an interdisciplinary cooperation project of the KIT research teams led by Uwe Strähle and Gerd Ulrich Nienhaus, the PhD students Volker Middel and Lu Zhuo developed new techniques to observe membrane repair processes with ultra-high resolution in real time in human cells and in muscle cells of zebrafish embryos. They proved that the repair patch assembling itself from repair proteins, such as dysferlin or annexines, also accumulated the phosphatidylserine lipid. Phosphatidylserine is a known appetizer for scavenger cells, the so-called macrophages.

The KIT researchers presented a movie that shows how the macrophages indeed latch to the repair patch and eat it up. Only after the patch has been removed, the cell envelope is fully restored. Thus, the repair of the membrane in muscle fibers requires, in addition to the formation of repair patches in the injured cell, the aid of macrophages roaming around within the muscle. The researchers further demonstrated that a short amino acid sequence in the dysferlin repair protein is responsible for the phosphatidylserine transport. It is remarkable that there are myopathy patients who have a defect precisely in this sequence of the dysferlin protein. The new findings may therefore contribute to the development of therapies against muscle atrophy.
-end-
Video: http://www.nature.com/articles/ncomms12875#supplementary-information

Karlsruhe Institute of Technology (KIT) pools its three core tasks of research, higher education, and innovation in a mission. With about 9,300 employees and 25,000 students, KIT is one of the big institutions of research and higher education in natural sciences and engineering in Europe.

KIT - The Research University in the Helmholtz Association

Since 2010, the KIT has been certified as a family-friendly university.

This press release is available on the internet at http://www.kit.edu

Karlsruher Institut für Technologie (KIT)

Related Macrophages Articles from Brightsurf:

New technology tracks role of macrophages in cancer spread
A Morgridge imaging study of macrophages -- immune cells that are important to human health, but paradoxically can help some cancers grow and spread -- is offering better ways to understand these cells and target them with immunotherapies.

UCalgary researchers discover how to capture images of cells at work inside our lungs
University of Calgary scientists have discovered how to capture ''live'' images of immune cells inside the lungs.

Researchers characterize important regulators of tissue inflammation, fibrosis and regeneration
Although macrophages (cells involved in the detection and destruction of bacteria and other harmful organisms as well as dead cells) are classified as immune cells functioning in the activation and resolution of tissue inflammation, it is now clear that they are critically involved in a variety of disease processes, such as chronic inflammatory diseases, tumor growth and metastasis and tissue fibrosis.

Assembly within the tumor center
Number of macrophages in tumor tissue enables prognosis of lung tumor progression.

'Cells-soldiers' turned to be more resistant than 'cells-combat medics'
Researchers from Sechenov University (Russia) and University of Pittsburgh (USA) discovered that the resistance of innate immune cells, macrophages, to ferroptosis -- a type of programmed cell death -- depends on the type of their activation.

New molecular mechanism that regulates the sentinel cells of the immune system
CNIC scientists have uncovered a new molecular mechanism that determines the identity and expansion of one of the cell types that work as immune sentinels in the body -- the macrophages of the serous cavities.

CAR macrophages go beyond T cells to fight solid tumors
Penn Medicine research shows genetically engineering macrophages -- an immune cell that eats invaders in the body -- could be the key to unlocking cellular therapies that effectively target solid tumors

Stroke: Macrophages migrate from the blood
Macrophages are part of the innate immune system and essential for brain development and function.

Double trouble: A drug for alcoholism can also treat cancer by targeting macrophages
The deadly nature of cancer stems from its ability to spread and grow inside the host.

Immune response in brain, spinal cord could offer clues to treating neurological diseases
An unexpected research finding is providing information that could lead to new treatments of certain neurological diseases and disorders, including multiple sclerosis and Alzheimer's.

Read More: Macrophages News and Macrophages Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.