Language and speech gene regulates neural wiring, scientists find
New research shows that the Foxp2 gene, which is known for its involvement in speech and language in humans, helps control the brain's neural wiring. Presented in the journal PLoS Genetics, the study was funded in part by a Marie Curie Intra-European Fellowship grant under the EU's Seventh Framework Programme (FP7). The findings help elucidate how the gene directs particular features of the development of the nervous system, helping bridge the gap between genes and complex aspects of brain function.
The study, carried out by researchers from France, the Netherlands, the United Kingdom and the United States, found that Foxp2 acts by tuning the expression levels of other genes. The researchers used genome-wide techniques to identify the major targets of Foxp2. Doing so helped them gain a better understanding of the roles it plays in biological pathways during the processes that generate, shape and reshape the nervous system.
Led by the Wellcome Trust Centre for Human Genetics, University of Oxford in the United Kingdom, the team says Foxp2 codes for a regulatory protein, fuelling our understanding of unusual aspects of brain function.
Just a decade ago, researchers found that mutations of the human gene triggered a rare form of speech and language disorder. So for the next 10 years, many investigations were launched into the human gene and corresponding versions found in other species. Scientists discovered, for instance, that the mutation influences vocal imitation in songbirds.
For the purposes of their study, the team, headed by the Wellcome Trust Centre for Human Genetics' Drs Sonja C. Vernes and Simon E. Fisher, probed the gene's role as a genetic dimmer switch, turning up or down the amount of product produced by other genes. Their screening of embryonic brain tissue led them to pinpoint a number of new targets regulated by Foxp2.
Several of these targets, they say, had already been recognised for their role in the connectivity of the central nervous system. The researchers discovered that changing Foxp2 levels in neurons affected the length and branching of neuronal projections, which experts believe are significant for modulating the wiring of the developing brain.
'We followed up our genomics data with functional experiments, showing that Foxp2 impacts on neurite outgrowth in primary neurons and in neuronal cell models,' the authors write. 'Our data indicate that Foxp2 modulates neuronal network formation, by directly and indirectly regulating mRNAs involved in the development and plasticity of neuronal connections.'
'Studies like this are crucial for building bridges between genes and complex aspects of brain function,' comments Dr Fisher, who also heads a newly established Language and Genetics Department at the Max Planck Institute for Psycholinguistics in the Netherlands. 'The current study provides the most thorough characterisation of Foxp2 target pathways to date. It offers a number of compelling new candidate genes that could be investigated in people with language problems.'