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Phosphorylation at glutamate receptor subunit 1(GluR1) Ser845 residue has been widely accepted to involve in GluR1-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor trafficking, but the in vivo evidence has not yet been established. One of the main obstacles is the lack of effective methodologies to selectively target phosphorylation at single amino acid residue. In this study, the Escherichia  coli-expressed glutathione- S-transferase-tagged intracellular carboxyl-terminal domain of GluR1 (cGluR1) was phosphorylated by protein kinase A for in vitro selection. We have successfully selected aptamers which effectively bind to phospho-Ser845 cGluR1 protein, but without binding to phospho-Ser831 cGluR1 protein. Moreover, pre-binding of the unphospho-cGluR1 protein with these aptamers inhibits protein kinase A-mediated phosphorylation at Ser845 residue. In contrast, the pre-binding of aptamer A2 has no effect on protein kinase C-mediated phosphorylation at Ser831 residue. Importantly, the representative aptamer A2 can effectively bind the mammalian GluR1 that inhibited GluR1/GluR1-containing AMPA receptor trafficking to the cell surface and abrogated forskolin-stimulated phosphorylation at GluR1 Ser845 in both green fluorescent protein–GluR1-transfected human embryonic kidney cells and cultured rat cortical neurons. The strategy to use aptamer to modify single-residue phosphorylation is expected to facilitate evaluation of the potential role of AMPA receptors in various forms of synaptic plasticity including that underlying psychostimulant abuse. [ABSTRACT FROM AUTHOR]

Behavioral sensitization of psychostimulants was accompanied by alterations in a variety of biochemical molecules in different brain regions. However, which change is actually related to drug-produced sensitization lacks of accurate clarification. In this study, we investigated the role of integrin-linked kinase (ILK) in both the induction and expression of cocaine sensitization. Conditional inhibition of ILK expression was established in the nucleus accumbens (NAc) core by microinjecting recombinant adeno-associated virus-carrying, tetracycline-on-regulated small interfering RNA which reversed the chronic cocaine-induced psychomotor sensitization, as well as the changes in protein kinase B Ser473 phosphorylation, dendritic density, and dendritic spine numbers locally. Importantly, the reversed psychomotor sensitization did not recover after cessation of the silencing for 8 days. We also demonstrated that inhibition of ILK expression pre- and during-chronic cocaine treatments blocked the induction of cocaine psychomotor sensitization and abolished the stimulant effect of cocaine on ILK expression. In contrast, inhibition of ILK expression in the NAc core has no significant effect on cocaine-induced stereotypical behaviors. This concludes that ILK is involved in cocaine sensitization with the earlier induction and later expression functioning as a kinase to regulate protein kinase B Ser473 phosphorylation and a scaffolding protein to regulate the reorganization of the NAc spine morphology. [ABSTRACT FROM AUTHOR]