Abstract
Learning and memory formation requires continuous synaptic plasticity at both the functional and structural level. The stability of synapse is maintained by bidirectional signals between pre- and post-synaptic molecules in response to synaptic activity. However, very little is known about molecules that are involved in such a transsynaptic action. Synaptotrophins (Sptn1-Sptn4) structurally belong to C1q/tumor necrosis factor (TNF) family. Recently, Sptn1 has been revealed to be glycoprotein secreted from cerebellar granule cell, and to regulate synaptic plasticity and synaptic integrity between parallel fiber-Purkinje cell (PF-PC) synapse. sptn1-null mice are ataxic, and exhibit molphological abnormalities of PF-PC synapse [e.g., naked spine, mismatched Postsynaptic density (PSD)]. Whereas sptn1 mRNA is predominantly expressed in the cerebellum, other members of synaptotrophin family, of which structure are highly similar to that of Sptn1, are expressed in not only cerebellum but also other brain regions. We hypothesized that the transsynaptic action of the secreted synaptotrophins plays a critical role in structural remodeling of synapses in various central nervous systems. Here we present the expression and the biochemical characteristic of Synaptotrophin family. [J Physiol Sci. 2006;56 Suppl:S31]
