Mouse models with high translational value Cell surface adhesion glycoproteins Cell surface adhesion glycoproteins are a primary mechanism through which connections of presynaptic axons and postsynaptic dendrites are elaborated in neuronal synapses.97,105 Mutations in cell surface protein genes have been reported with comparatively high frequency in neurodevelopmental disorders. Individuals with autism have been identified with mutations #see more keyword# in NEUREXIN1, NEUROLIGIN3, NEUROLIGIN4, SHANK2, SHANKS, and CNTNAP2. For each of these rare mutations, a small number of individuals with the mutations who meet the diagnostic criteria for autism spectrum disorder

has been identified.106-109 Inhibitors,research,lifescience,medical Mice with homologous mutations in these genes are available from several excellent molecular genetics laboratories and from The Jackson Laboratory repository. Shank3 knockout mice Shank3

knockout mice present a particularly fascinating example of the importance of the location of the mutation within the gene. The Shank3 gene includes an ankyrin repeat domain, a PDZ domain, and a Homer binding domain.110-112 Five distinct lines of Shank3 knockout mice with mutations at these various sites were generated and phenotyped Inhibitors,research,lifescience,medical in the past 2 years.71,81,113,114 Two lines of Shank3 knockouts containing the mutation at the ankyrin domain displayed impairments in excitatory Inhibitors,research,lifescience,medical neurotransmission and long-term potentiation, but were predominantly normal on standard measures of sociability, with only small genotype differences detected in ultrasonic vocalizations and repetitive behavior.71,81 Inserting the mutation at the Homer binding site resulted in mice with more social interactions, primarily in the form of aggression, along with mostly normal dendritic spines, reduced long-term potentiation, and enhanced long-term depression.113 When the mutation was in the PDZ domain, Shank3 knockouts displayed much more severe phenotypes, including high spontaneous self-grooming

Inhibitors,research,lifescience,medical resulting in skin lesions, impaired sociability, reduced corticostriatal excitatory transmission, longer dendritic spines, and lower density of dendritic spines, and as compared with wild-type controls.81 These divergent outcomes of mutations at differing sites within the same gene provide a unique opportunity to understand the binding partners and their downstream signaling actions that determine the severity of symptoms in humans. For example, deficits in mGluRS signaling have been reported after Shank3 knockdown in neuronal cultures.115 Augmentation of mGluRS activity could be beneficial in cases of autism with SHANK3 mutations, and in individuals with Phelan-McDermid syndrome, an intellectual disability syndrome in which the SHANK3 mutation is central to the 22q13 chromosomal deletion.