engleski

Neuroplastin expression and submembrane localization are affected by membrane ganglioside composition

Synaptic glycoprotein neuropastin (Np) is involved in synaptic plasticity and complex molecular events underlying learning and memory formation. Np exists in two isoforms, Np55 and Np65. Being a membrane protein, its function and localization within specific membrane subdomains like lipid rafts (LR) are most probably affected by specific lipid microenvironment. This study aimed to investigate the effect of membrane ganglioside composition on total and brain regional protein expression and submembrane localization of Np using St8sia1 null mice with impaired synthesis of gangliosides. Brains of adult wild type (WT) and null mice littermates were used. Protein expression of both Np isoforms in homogenates was analyzed by Western blotting. Immunohistochemical staining was performed on frozen brain tissue slices using an antibody specific for both isoforms. LR and non-raft (nLR) fractions from cortices and cerebella were isolated by ultracentrifugation in discontinuous sucrose gradients, and submembrane localization of Np isoforms analyzed by Western blotting. Results revealed statistically lower amounts of Np55 and Np65 in both cortices and cerebella of null mice compared to their WTs. Immunohistochemical staining revealed lower intensity of Np staining in the cortex and cerebellar molecular layer of null mice compared to WT mice. The amount of both isoforms positioned within cortical LR of null mice was statistically lower than those positioned within LR derived from WT animals. Results show that proper ganglioside environment is critical for specific Np functions, indicating novel roles of gangliosides as co-players in molecular basis of cognitive processes.

glycosphingolipids ; neuroplastin

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