Mirror movement syndrome: a research team discovers one of the causes

The D team^r Frédéric Charron, researcher at the Montreal Clinical Research Institute (IRCM) and professor at the Faculty of Medicine of the University of Montreal, has just made a promising breakthrough in understanding the origins of the mysterious mirror movement syndrome.

Mirror movement syndrome is an inherited neurological disease that manifests itself from a young age, mainly in the arms and hands. In people who suffer from it, the right hand involuntarily reproduces the movements of the left hand and vice versa, hence the name “mirroring movements”. This syndrome can cause arm pain during prolonged activities and cause difficulty performing tasks requiring left-right coordination.

“Mirror movement syndrome disrupts the daily life of those affected. Simple actions like opening a bottle of water can become arduous, just like playing a musical instrument,” notes Dr.^r Charron, who directs the Research Unit in Molecular Biology of Neural Development at the IRCM.

Carried out in collaboration with the D team^r Greg Bashaw, of the University of Pennsylvania, this study, whose first authors are Kaiyue Zhang, doctoral student at the IRCM, and the D^re University of Pennsylvania student Karina Chaudhari was published in the journal Science Signaling.

Axonal guidance of neurons and the cytoskeleton involved

The cellular mechanism behind mirror movements is a defect in a phenomenon that is called “axonal guidance.”

During embryonic development, neurons extend their axon, a long cellular cable that allows them to connect specific areas of the body together, thus establishing nerve connections. Axonal guidance is the set of processes that control the elongation of the axon and direct its navigation. Among other things, it allows each neuron to be linked to its target. It is therefore crucial for the proper development of the nervous system.

Various so-called guidance molecules direct axons toward their targets, acting like signal signs directing axons toward their destination. To do this, when these guidance molecules are detected by the axons, they must initiate the movement of the axon. This movement requires complex molecular machinery that is still poorly understood.

However, in this study, the research team shows that the machinery required for guidance is in fact the cytoskeleton. The cytoskeleton is, as its name indicates, the skeleton of the cell, which provides it with a certain rigidity, a bit like the bones of the body which, through their rigidity, allow movement.

Understanding the mechanisms causing mirror movements is essential for the search for innovative treatments. The work of the laboratory of D^r Charron potentially open the door to promising new targets for the treatment of mirror movement syndrome as well as other diseases resulting from defects in the development of the nervous system.

About this study

This study was made possible thanks to the support of the Canadian Institutes of Health Research, the Neurobasis project of the Canada Foundation for Innovation, the Fonds de recherche du Québec – Santé sector, the China Scholarship Council, the National Science Foundation and the National Institutes of Health. Frédéric Charron directs the Canada Research Chair in Developmental Neurobiology.

The D teams^re Myriam Srour, from the Montreal Children’s Hospital, from D^r Junmei Wang, of the University of Pittsburgh, and D^r Baoyu Chen of the University of Iowa also contributed to this work.