Abstract: This relates to a discovery of a cell surface protein, namely NgR2, that is implicated in regulation of blood-brain barrier (BBB). In addition, the invention relates methods for identifying agents that modulate BBB permeability. Furthermore, the invention relates to methods of delivering therapeutic agents to the central nervous system by increasing BBB permeability.

Abstract: Methods are provided for enhancing myelination. Myelination is enhanced by administration of agents that are inhibitors of ?-secretase. Methods of screening for pharmaceutically active compounds that enhance myelination, and for genes involved in myelination are also provided.

Abstract: C1q is shown to be expressed in neurons, where it acts as a signal for synapse elimination. Methods are provided for protecting or treating an individual suffering from adverse effects of synapse loss. These findings have broad implications for a variety of clinical conditions, including Alzheimer's disease.

Abstract: Soluble proteins, e.g. thrombospondins, can trigger synapse formation. Such proteins are synthesized in vitro and in vivo by astrocytes, which therefore have a role in synaptogenesis. These thrombospondins are only expressed in the normal brain exactly during the period of developmental synaptogenesis, being off in embryonic brain and adult brain but on at high levels in postnatal brain. Methods are provided for protecting or treating an individual suffering from adverse effects of deficits in synaptogenesis, or from undesirably active synaptogenesis. These findings have broad implications for a variety of clinical conditions, including traumatic brain injury, epilepsy, and other conditions where synapses fail to form or form inappropriately. Synaptogenesis is enhanced by contacting neurons with agents that are specific agonists or antagonists of thrombospondins. Conversely, synaptogenesis is inhibited by contacting neurons with inhibitors or antagonists of thrombospondins.