Simple genetic path creates brain architecture
13 August 2008
Scientists at the MRC National Institute for Medical Research have identified two genes that help co-ordinate the architecture of the brain.
Brain cells are always generated at a distance from their final location and so must travel along specific routes for the brain to be put together correctly.
‘‘This episode of neuronal migration is of considerable importance for the correct development of the brain. Mutations in genes that cause migration defects in the cerebral cortex during foetal life often result in severe mental retardations,’’ explains lead author Dr Francois Guillemot of NIMR.
The researchers set out to learn how newly generated brain cells move to the correct part of the brain to build a fully functioning organ. They focused on cells belonging to the cerebral cortex, the layer of grey matter around the brain involved in movement, learning and perception. Their findings are published in Nature.
The researchers blocked the expression of a gene called Rnd2 in developing neurones in mouse embryos. They found that the neurones unable to express Rnd2 could not follow the usual migration route to the cerebral cortex. In contrast brain cells that were not blocked switched on Rnd2 just before migration began.
Further investigation revealed the product of a second gene, Neurogenin2, prompts expression of Rnd2 and in doing so coordinates development of the cerebral cortex.
‘‘What we have learnt is that the Rnd2 gene regulates brain cell migration to the cerebral cortex and that it is activated by the Neurogenin2 gene. This study provides a striking demonstration that a complex cellular process such as the initiation of neuronal migration can be regulated by a simple genetic pathway,’’ concludes Dr Guillemot.
Original research paper: Neurogenin 2 controls cortical neuron migration through regulation of Rnd2 by Guillemot et al is published in Nature.
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