Scientists at Rutgers, The State University of New Jersey, have discovered a biological process in brain cell development that may help explain some causes of mental retardation.
This understanding may one day help other researchers develop therapies that can reduce specific forms of retardation.
In a paper published in The Journal of Neuroscience, Rutgers cell biologists Hongxin Chen and Bonnie Firestein show that proteins of the Rho family, when excessively present in developing brain cells known as neurons, inhibit another protein that promotes healthy neuron development. Firestein earlier demonstrated how this protein, called cypin, promotes healthy branching patterns in the tree-like structures at the end of neurons that receive signals. Inadequate branching in these structures, called dendrites, has been observed in conditions such as Alzheimer's disease, autism and some types of mental retardation.
"Imbalances of Rho proteins have been known to affect dendrite branching, and therefore have been implicated in causing mental retardation," said Firestein, associate professor of cell biology and neuroscience. "How this happens, however, has not been clear. Now we're seeing that Rho proteins signal other proteins downstream. In our case, we discovered that a type of Rho protein called RhoA is inhibiting cypin production when it is overactive or present in excess. The resulting lack of cypin is detrimental to healthy branching development in dendrites."