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7 Marzo 2017

A trail of bread crumbs: that's how microRNAs help neurons find their way during the development of the nervous system

A research team led by CIBIO at the University of Trento has identified a fundamental biological mechanism in the creation of correct neuronal connections that, when altered, may cause neurodevelopmental disorders. The full study on Cell Reports

A study coordinated by Marie-Laure Baudet of CIBIO – University of Trento, recently published in Cell Reports, identified one of the basic processes in the formation of neuronal connections. The study describes how microRNAs help axons interpret the messages from the environment along the path that guides neurons to their target cells.
Axons have a long distance to cover to reach their target cells in a very complex environment but, like in the tale of Litle Thumb, they manage to find their way thanks to “chemotropic” molecules (the breadcrumbs along the path) which guide them precisely to their final destination. The study demonstrates the fundamental role of microRNAs in recognizing the right path encoded by these chemotactic molecules. If a specific microRNA is experimentally removed from an axon, the latter loses its ability to interpret the signals it receives from the environment. Not knowing where to go, the axon fails to reach its target and establishes aberrant neuronal connections. 
Micro-RNAs are small molecules of ribonucleic acid that are involved in a number of physiological processes both in plants and in animals. Dr. Baudet's team found out that these molecules govern an essential regulatory mechanism for the development of neural circuits, from within axons. During brain development, neurons extend protrusions called axons whose task is to connect neurons to their target cells. 
The development of connections among neurons is absolutely essential during brain development. These connections, once formed, create a thick network of neural circuits which are the basis of all brain activity, from the basic processing of sensory information to higher cognitive functions such as decision-making. A failure in this phase, during the creation of the circuits, can have devastating consequences and may lead to serious cognitive and behavioral disorders. Unravelling the molecular mechanisms that lead to the formation of neural circuits is therefore critical to further our understanding of these pathologies and to inform the development of novel clinical therapies. 
These key findings are the result of a 5-year research study in collaboration with the University of Cambridge, where Marie-Laure Baudet worked until 2012. The researcher then moved to Italy, where she founded her own research laboratory at CIBIO in Trento, thanks to the Career Development Award Program of the Armenise-Harvard Foundation. The laboratory is currently receiving funding from the Armenise-Harvard Foundation in the USA, the European Commission, and the Italian Ministry of Education, Universities and Research (MIUR).