Converging Signaling Pathways

Pten conditional knock-out mice display enlarged brains and social behavioral deficits

Appropriate model systems for study of the complex and fundamentally human challenge of autism will be vitally important to solving autism because they allow researchers to study the underlying biology in a way that is not possible in humans. Finding an animal model system with similar behavioral tendencies as humans allows researchers to study which biochemical pathways break down in autism and, most importantly, how they can be treated. In 2007, researchers added an important new model system to their arsenal, the "Pten conditional knockout" mouse.

PTEN is a gene that encodes for a protein involved in several critical signaling pathways inside cells, including metabolism, growth and survival. To carry out its cellular duties, PTEN interacts with several other important proteins in a biochemical signaling cascade. Other proteins in this signaling pathway have previously been tied to developmental disorders such as Tuberous Sclerosis and Neurofibromatosis. In 2005, researchers found that within a small subset of individuals with autism and macrocephaly (large heads) 17% had mutations in the PTEN gene. This raised the possibility that disrupting PTEN activity, and the signaling pathways within which it functions, may result in some forms of autism. This year researchers succeeded in using complex genetic manipulations to shutdown the mouse version of the gene (Pten) in the brain of young mice. Surprisingly, not only did these animals grow larger brains, the mice also displayed abnormal social behaviors and seizures, both of which can be features of autism.

These results provided important data supporting the emerging relevance of cellular signaling pathways to autistic behaviors, and are now focusing some researchers on specific molecules that could potentially become targets for cell-based therapeutics.