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In multicellular organism cell adhesion to other cells and to the extracellular matrix is very tightly regulated. Depending on the tissue, the attachment structures are adjusted to tolerate various pulling forces and sometimes the attachments are opened and reorganized. For force tolerance adhesion proteins in the cellular membrane need to be connected to intracellular structural elements, the cytoskeleton, and this connection is the key regulatory point. The research groups of Professor Jari Ylänne from Department of Biological and Environmental Science at the Ä¢¹½Ö±²¥ and Professor Nick H. Brown from Department of Physiology, Development and Neuroscience at the University of Cambridge have studies for several years so called mechanosensor proteins, whose function change according to pulling force. The research teams found several new mechanisms how the structure and function of muscle attachment sites are regulated during development.

Novel functions for proteins

Researchers utilized the flight muscles of Drosophila melanogaster fruit flies. These are the muscles in flies that most closely resemble human skeletal muscles and their attachment sites are similar to myotendinous junctions, the connections between muscle and tendon. Drosophila flies are very useful model organism, because their development can be relatively easily followed under microscope, thousands mutants and fluorescence protein marker fly lines are available, genetic modification and genetic crossing is relative easy. Furthermore, flies have often less genes affecting same functions and thus the effects of individual mutations are easier to observe.

- By combining efforts between the two groups, we found a new functional link between three mechanosensor proteins. These protein act in concert to strengthen the attachment sites when muscle contracts. Alterations of these proteins, or their specific mechanosensory sites caused disorganization of muscle attachment sites and reduced the flying capacity of the flies, says Professor Jari Ylänne from Department of Biological and Environmental Science and Nanoscience Center at the Ä¢¹½Ö±²¥.

This research is important for the basic understanding of regulation of muscle function for instance in muscle dystrophy patients. Furthermore, the results may help us to understand muscle adaptation to physical activity and sports.

The research published in eLife on 20th of July, 2018. This research was supported by Academy of Finland and Jenny and Antti Wihuri Foundation in Finland as well as by Wellcome Trus, Medical Research Council and Biotechnology, and Biological Sciences Research Council in the United Kingdom.

_{Picture: Transmission electron microscope micrograph from the muscle attachment site studied in the report. The left image is a normal fligh muscle, the right is from a diseased muscle. In the right image a gray, elastic zone is largely missing. Figure taken from eLife 2018;7:e35783 doi: , reproduced under CC BY 4.0}

More information:

• Prof. Jari Ylänne, +358 50 428 5273, jylanne@jyu.fi
• References: Green, H.J., Griffiths, A.G.M., Ylänne, J., and Brown, N.H. (2018). Novel functions for integrin-associated proteins revealed by analysis of myofibril attachment in Drosophila, eLife 2018;7:e35783 doi:
• Link to article: