Applications of Active Endosialidase for the Study ofNCAM

Identification of polysialic acid as posttransladonal modification of NCAM has been based on the release of oligomers of sialic acid from it by incubation with 

The stability of endosialidase and its activity under physiological pH and ion conditions have promoted its use under various experimental setups in vivo. In early studies it has already been shown that injection of endosialidase into the brain during development results in altered responses of developing axons to their environment. 

EndoNF injection into the fourth ventricle of PO rats results in the reduction of collateral branching of corticospinal axons [162]. Injection of endosialidase NF into the lateral ventricle of PI mice results in rapid diffusion of the enzyme throughout the brain. The removal of polysialic acid induces aberrant mossy fiber innervation and ectopic synaptogenesis in the hippocampus [163]. 

Removal of polysialic acid by treatment with endosialidase has demonstrated the involvement of polysialic acid in dynamic cellular processes as varied as migration of neuronal precursor cells, axonal outgrowth, synaptogenesis, physiological and morphological synaptic plasticity, and control of circadian rhythm [63, 75, 153, 164-174]. One example on the application of endosialidase in cell culture studies is 

Although the vast majority of polysialic acid in the nervous tissue is carried by the NCAM molecule, it is not certain whether all the effects recorded by the use of endosialidase are specifically due to its action on NCAM or an action on other molecules like SynCAM 1 [63]. 

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