Interaction of the ubiquitin carboxyl terminal esterase L1 with alpha(2)-adrenergic receptors inhibits agonist-mediated p44/42 MAP kinase activation.

Neuroprotective effects of alpha(2)-adrenergic receptor (AR) agonists are mediated via the alpha(2A)AR subtype, but the molecular mechanisms underlying these actions are still not elucidated. A two-hybrid screen was performed to identify new proteins that may control alpha(2)AR receptor function and trafficking. This screen identified the ubiquitin carboxyl-terminal hydrolase-L1 (Uch-L1), a ...
protein associated with Parkinson's disease, as alpha(2)AR interacting protein. This interaction was confirmed and evaluated by GST pull down assays demonstrating that Uch-L1 binds preferentially to the alpha(2A)AR subtype and only with less affinity to alpha(2B)AR and alpha(2C)AR. Co-immunoprecipitation of epitope-tagged proteins confirmed the specificity of this interaction in vivo. Moreover, co-transfection of a truncated G-protein coupled receptor kinase-DNA preventing alpha(2)AR phosphorylation led to an increased signal-strength of coimmunoprecipitated Uch-L1. Confocal laser microscopy showed that interaction of alpha(2A)AR and Uch-L1 occurred in the cytoplasm. alpha(2)AR agonist mediated activation of p44/42 MAP Kinase was drastically decreased in the presence of Uch-L1 indicating a functional relevance of this interaction. These findings may present a mechanism contributing to subtype-specific alpha(2)AR trafficking and a potential pathway for the neuroprotective effects of alpha(2)AR agonists.
Mesh Terms:
Amino Acid Sequence, Cell Line, Humans, Immunoprecipitation, Mitogen-Activated Protein Kinase 1, Mitogen-Activated Protein Kinase 3, Molecular Sequence Data, Phosphorylation, Protein Binding, Receptors, Adrenergic, alpha-2, Recombinant Fusion Proteins, Signal Transduction, Two-Hybrid System Techniques, Ubiquitin Thiolesterase
Cell. Signal.
Date: Oct. 01, 2009
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