The gene Foxp2 acts like a “genetic dimmer switch” that regulates wiring in the developing brain. It does this by controlling the products of other genes, resulting in changes in the length and number of connections between brain cells, say the authors of a new study published in the 7 July issue of the open-access journal PLoS Genetics.

The lead authors of the study are Sonja C Vernes and Simon E Fisher from the Wellcome Trust Centre for Human Genetics, in Oxford, UK, and the Max Planck Institute (MPI) for Psycholinguistics in Nijmegen, The Netherlands.

In 2001, Fisher and his team discovered that mutations of Foxp2 were linked to a rare speech and language disorder. The discovery prompted a number of projects looking into Foxp2 and its equivalent in other animals, including one study that found it affects the ability of birds to imitate songs.

In this study, Vernes, Fisher and colleagues found that Foxp2 fine tunes how much and how little other genes (they refer to these as the “downstream targets”) are expressed and therefore how much of their proteins are made.

They used genome-wide techniques to sift through thousands of genes to find which ones Foxp2 was switching on and off in the brains of mouse embryos. Remarkably, many of these “downstream targets” are known to be important for developing connections between neurons in the early stages of development in the central nervous system.

In the next phase of the study, they found that changing levels of Foxp2 affected the length and branching of neuronal projections: a key feature of how the wiring is fixed in the developing brain, something that is important in language learning.

The genes that control these early stages of brain development also happen to be genes that affect connectivity between neurons later on, and even in the mature brain it may be that they influence brain plasticity, or the ability of the brain to rewire itself, said the researchers in a press statement.

Fisher, who is director of MPI’s Language and Genetics department, said this study is a good example of how to investigate what happens between genes and various complex brain functions.

It also “offers a number of compelling new candidate genes that could be investigated in people with language problems,” he added.

“Foxp2 Regulates Gene Networks Implicated in Neurite Outgrowth in the Developing Brain.” Vernes SC, Oliver PL, Spiteri E, Lockstone HE, Puliyadi R, and others.
PLoS Genetics 2011; 7(7): e1002145.

Additional source : MPI.

Written by: Catharine Paddock, PhD