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Autism spectrum disorders comprise a range of neurodevelopmental disorders characterized by deficits in social interaction and communication, and by repetitive behaviour (1). Mutations in synaptic proteins such as neuroligins (2,3), neurexins (4), GKAPs/SAPAPs (5) and ProSAPs/ Shanks (6-10) were identified in patients with autism spectrum disorder, but the causative mechanisms remain largely unknown. ProSAPs/ Shanks build large homo- and heteromeric protein complexes at excitatory synapses and organize the complex protein machinery of the postsynaptic density in a laminar fashion (11,12). Here we demonstrate that genetic deletion of ProSAP1/Shank2 results in an early, brain-region-specific upregulation of ionotropic glutamate receptors at the synapse and increased levels of ProSAP2/Shank3. Moreover, ProSAP1/[Shank.sup.-/-] mutants exhibit fewer dendritic spines and show reduced basal synaptic transmission, a reduced frequency of miniature excitatory postsynaptic currents and enhanced JV-methyl-D-aspartate receptor-mediated excitatory currents at the physiological level. Mutants are extremely hyperactive and display profound autistic-like behavioural alterations including repetitive grooming as well as abnormalities in vocal and social behaviours. By comparing the data on ProSAP1/[Shank.sup.-/-] mutants with ProSAP2/ Shank3α[β.sup.-/-] mice, we show that different abnormalities in synaptic glutamate receptor expression can cause alterations in social interactions and communication. Accordingly, we propose that appropriate therapies for autism spectrum disorders are to be carefully matched to the underlying synaptopathic phenotype., Many of the recently identified autism spectrum disorders (ASD) candidate genes code for proteins of excitatory synapses (13-15), suggesting that these disorders may arise from molecular imbalances of synaptic connections. [...]

In ecdysozoan protostomes, including arthropods and nematodes, transcription factors of the GATA family specify the endoderm: Drosophila dGATAb (ABF/Serpent) and Caenorhabditis elegans END-1 play important roles in generating this primary germ layer. end-1 is the earliest expressed endoderm-specific gene known in C. elegans and appears to initiate the program of gene expression required for endoderm differentiation, including a cascade of GATA factors required for development and maintenance of the intestine. Among vertebrate GATA proteins, the GATA-4/5/6 subfamily regulates aspects of late endoderm development, but a role for GATA factors in establishing the endoderm is unknown. We show here that END-1 binds to the canonical target DNA sequence: WGATAR with specificity similar to that of vertebrate GATA-1 and GATA-4, and that it functions as a transcriptional activator. We exploited this activity of END-1 to demonstrate that establishment of the vertebrate endoderm, like that of invertebrate species, also, appears to involve GATA transcriptional activity. Like the known vertebrate endoderm regulators Mixer and Sox17, END-1 is a potent activator of endoderm differentiation in isolated Xenopus ectoderm. Moreover, a dominant inhibitory GATA-binding fusion protein abrogates endoderm differentiation in intact embryos. By examining these effects in conjunction with those of Mixer- and Sox17 [Beta]-activating and dominant inhibitory constructs, we further establish the likely relationships between GATA activity and these regulators in early development of the vertebrate endoderm. These results suggest that GATA factors may function sequentially to regulate endoderm differentiation in both protostomes and deuterostomes.