Abstract
Recent studies indicate that glutamatergic signaling involves, and is regulated by, thiol modifying and redox-active compounds. In this study, we examined the role of a reactive cysteine residue, Cys-893, in the cytosolic C-terminal tail of GluA1 AMPA receptor as a potential regulatory target. Elimination of the thiol function by substitution of serine for Cys-893 led to increased steady-state expression level and strongly reduced interaction with SAP97, a major cytosolic interaction partner of GluA1 C-terminus. Moreover, we found that of the three cysteine residues in GluA1 C-terminal tail, Cys-893 is the predominant target for S-nitrosylation induced by exogenous nitric oxide donors in cultured cells and lysates. Co-precipitation experiments provided evidence for native association of SAP97 with neuronal nitric oxide synthase (nNOS) and for the potential coupling of Ca2+-permeable GluA1 receptors with nNOS via SAP97. Our results show that Cys-893 can serve as a molecular target for regulatory thiol modifications of GluA1 receptors, including the effects of nitric oxide.
Highlights
AMPA receptors are tetrameric ion channels which mediate fast excitatory glutamate signaling in the central nervous system
We have examined the role of GluA1 Cys-893 on the SAP97 interaction with full-length molecules in live cells and examined its potential as a target for S-nitrosylation
Prompted by findings on stimulation of nitric oxide formation by Ca2+-permeable AMPA receptors [34,35,36], we have investigated the potential of SAP97 in serving as a physical link between neuronal nitric oxide synthase (nNOS) and AMPA receptors, in analogy with PSD-95 –mediated association of NMDA receptor with nNOS
Summary
AMPA receptors are tetrameric ion channels which mediate fast excitatory glutamate signaling in the central nervous system. AMPA receptor subunits, GluA1-4, share a modular structure consisting of extracellular N-terminal (NTD) and ligand-binding domains (LBD), a transmembrane ion channel domain (TMD) and a cytosolic C-terminal tail (CTD) [1,2]. GluA1 features an ~80 amino acid long cytosolic tail which provides binding sites for interacting proteins and carries a class I PDZ binding motif at the C-terminus. The cytosolic interaction partners identified to date include four PDZ domain proteins: SAP97 [8,9], mLin-10 [10], Shank3 [11] and sorting nexin 27 [12]. SAP97, a member of the PLOS ONE | DOI:10.1371/journal.pone.0171489 February 2, 2017
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