Distinct Expression Of δ-catenin And Spinophilin In Cerebellum Of Rat Of Different Age

Nerve aging is the inevitably result of vital movement. Investigating the mechanism of nerve aging and the methods of delaying is a vital subject in neuroscience. In the research of brain aging, synaptic plasticity is of great interest.δ-catenin and spinophilin are newly identified proteins that distribute in dendrite of neuron. They both play a important role in synaptic plasticity.δ-catenin belongs to the p120-catenin (p120ctn) protein family, which is characterized by sequence that bind to the juxtamembrane segment of the classical cadherins.δ-catenin is the only member of this family that is expressed specifically in neurons, where it binds to PDZ domain proteins in the post-synaptic compartment. By virtue of its restriction to the post-synaptic area,δ-catenin can regulate the synaptic input and plasticity. Spinophilin displays a remarkably distinct localization to the heads of dendritic spines and has therefore been named spinophilin. Spinophilin has the properties of a scaffolding protein localized to the cell membrane and contains a single consensus sequence in PSD95/DLG/zo-1. Spinophilin is the a novel targeting subunit for PP1, which directs the enzyme to those substrates in the dendritic spine compartment, e.g., neurotransmitter receptors, which mediate the regulation of synaptic function and plasticity by PP1. Cerebellum is the ideal model system for the research of neuron aging.Our experiment established model of natural neuron aging. The distribution ofδ-catenin and spinophilin in the cerebellum of different age rat was detected by immunohistochemical method. The expression level ofδ-catenin and spinophilin was detected by image analysis system and western blot. RT-PCR was used to detect the mRNA level ofδ-catenin and spinophilin in the cerebellum of different age rat.The immunohistochemical method showed thatδ-catenin and spinophilin mainly expressed in the molecular and granular layer of cerebellum.δ-catenin and spinophilin moderately expressed in the Purkinje cells of young and middle-aged rats, and less expressed in the Purkinje cells of old rats. Western blot showed that the expression ofδ-catenin and spinophilin were at the highest level in the cerebellum of middle-aged rat, and at the lowest level in the cerebellum of old rat. RT-PCR results indicated that the age-related changes of mRNA level ofδ-catenin and spinophilin in the cerebellum was basically coincident with those ofδ-catenin and spinophilin expression in western blotOur experiment showed that the expression ofδ-catenin and spinophilin in the cerebellum of rat varied with age, and the changes might be related with the alteration in synaptic number, structure and function in the cerebellum of different age rats.