Study reveals new mechanism for nerve growth

A huge number of nerves must be precisely wired together during the formation of our complex nervous system. All of these connections must be made accurately to allow the brain to faithfully control our movements, thoughts and behaviours. Researchers from the Department of Developmental Neurobiology at IoPPN, King’s College London, in collaboration with the Institute of Neuroscience and the Department of Genetics at Trinity College Dublin, have discovered a new mechanism that guides growing nerves across the midline of the nervous system. The findings, published in the scientific journal Development, contribute to a better understanding of how nerves grow, an essential step towards developing potential therapies to aid regrowth of nerves after brain injury or disease.

In insects and vertebrates, the two symmetrical halves of the central nervous are separated by a specialized group of cells. In the fruit fly, Drosophila, these are called the midline cells. Many axons cross the midline to interconnect the left and right sides of the central nervous system, a process that is critical for neurons to form the proper connections. Professor Guy Tear, from Department of Developmental Neurobiology, has found that a Drosophila protein called Mud, which is also present in humans where it is known as NuMA, plays a role in attracting axons to the midline and so direct them along their correct pathways in the nervous system.

Acting alongside other molecules, the Mud protein provides an alternative mechanism to guide growing nerves across the midline of the nervous system. Professor Kevin Mitchell, from Trinity College Dublin, commented "the identification of Mud/NuMA’s function in guiding growing nerves opens up a new molecular pathway for investigation, which may play important roles in other organisms, including humans". Mud potentially functions to polarise components in neurons to direct nerve growth. Professor Tear added "our knowledge of how neurons grow is far from complete but this research demonstrates that a number of molecular pathways co-operate to ensure neural connections are formed correctly".

Further work will identify precisely how Mud directs nerves, whether this process is conserved and if this pathway offers an alternative mechanism to stimulate regrowth.

This work was supported by a grant from the Biotechnology and Biological Sciences Research Council.

Paper reference: Mushroom body defect is required in parallel to Netrin for midline axon guidance in Drosophila. Cate S, Gajendra S, Alsbury S, Raabe T, Tear G, Mitchell KJ. Development 2016: doi: 10.1242/dev.129684 

For further information on this story or about the department please contact Andreia Carvalho, Head of Scientific Affairs, Department of Developmental Neurobiology, King’s College London (andreia.carvalho@kcl.ac.uk).

The Department of Developmental Neurobiology is part of the Institute of Psychiatry, Psychology & Neuroscience at King's College London.