Molecular mechanisms of retinal axon branching and synaptogenesis

SPIG1是一种功能未知的分泌性分子，由卵泡抑素样结构域、细胞外钙结合结构域和两个免疫球蛋白样结构域组成。我在这里研究了SIPIG1在视网膜轴突分支形成、轴突末端发育和突触形成过程中的作用。我发现SIPIG1与一种神经营养受体相互作用。我还研究了SPIG1参与发育过程中突触形成的可能性。在SPIG1缺失的背视网膜中，视神经顶盖的浅层变薄。但突触结构和突触位置正常。这些结果表明，SPIG1参与了发育中的视网膜轴突分支的形成和完善，也可能作为轴突分泌的调节因子，参与了顶盖内视网膜轴突神经支配的局部细胞外蛋白水解。

SPIG1 is a secretory molecule of unknown function, which is composed of a follistatin-like domain, an extracellular calcium-binding domain, and two immunoglobulin-like domains. I have here investigated the role of SIPIG1 during the branch formation, elaboration of axon terminals and synaptic formation in retinal axons. I found that SIPIG1 interacts with one of a neurotrophic receptor. I also investigated the possibility that SPIG1 is involved in synaptic formation during development. In SPIG1 knock-down dorsalretina, the superficial layers of the optic tectum were thin. However, the synapse structure and synaptic positions were normal. These results indicate that SPIG1 is involved in branch formation and refinement of developing retinal axons, and also SPIG1 might function as an axonally secreted regulator of the local extracellular proteolysis involved in the innervation by retinal axons within the tectum.