Of Can Regulate Beta-catenin Phosphorylation Of Synaptic Formation

Calcineurin(CaN) is a serine / threonine protein phosphatase,which is regulated by Ca2+/Calmodulin(CaM).It plays an important role in neuronal function through regulating phosphorylation state of key proteins of neuron.β-catenin is a key regulator of synaptic connection and of functional synapses formation. To identify the relationship between CaN andβ-catenin in neuronal synaptogenesis, CsA and FK506 was applied to specifically inhibit the CaN activity in hippocampal neurons, then we detectedβ-catenin expression andβ-catenin phosphorylation. Here, we choose synaptophysin, a membrane protein of neuron synaptic vesicles, as a specific celluar marker to detect the capacity of synaptogenesis.Test procedures and results are as follows: first, isolate and culture primary rat hippocampal neurons; and then treat hippocampal neurons with four kinds of conditions, i.e. the control group, ethanol (vehicle) group, CsA and FK506 group; finally detect the expression of synaptophysin andβ-catenin and its phosphorylation at Ser33 by imunocytochemistry and western blot. The results showed that in primary rat hippocampal neurons there was no significant difference ofβ-catenin between the control group and ethanol group, also between CsA and FK506 group. But once compared with the control group, there had significantly increasedβ-catenin within CsA and FK506 groups. As for the phosphorylatedβ-catenin, no significant difference was found between the control group and ethanol group, but significantly decrease was found when CsA group and FK506 group were compared with the control group; there was no significant difference on Synaptophysin between control group and ethanol group, but significant increase when the CsA group and FK506 group was compared with the control group.These results showed that when CaN activity was inhibited, the phosphorylatedβ-catenin would be reduced and its ubiquitination degradation pathway was inhibited, this led to the increased level ofβ-catenin appeared after CaN was inhibited. Simultaneously, there also had increased synaptophysin within the neurons of CsA group and FK506 group. This suggest that CaN can regulateβ-catenin-mediated gene transcription by adjustingβ-catenin ubiquitination degradation, further affect the synapse formation of hippocampal neurons.