FIGURE 1.

D2R activation promotes HTTN660 dephosphorylation on Ser-421 via an okadaic acid-insensitive phosphatase. HA-D2R along with the first 660 amino-terminal residues of the HTT (HTTN660) fused to the GFP were transiently overexpressed in HEK293T (2 μg each). A, Western blots and densitometry analysis of phospho-Ser-421 HTT levels in extracts prepared from cells treated for 45 min with 20 μm apomorphine (Apo), bromocriptine (Bromo), or NPA or untreated controls. B, Western blots and densitometry analysis representing the opposite effect of D2R agonist (apomorphine, 20 μm for 45 min) versus antagonists (haloperidol (Halo) or raclopride (Raclo), 20 μm for 45 min each) on phospho-Ser-421 HTT levels. C and D, cells were incubated with 250 nm OA (C) or 10 μm OA, for 45 min (D) before apomorphine stimulation (20 μm, 45 min). IB, immunoblot. E, cells were pretreated with 10 μm cypermethrin (Cyper) or 2 μm cyclosporin A (CsA), for 30 min before 20 μm apomorphine was applied to the culture medium for 45 min. In all experiments, solvents used to dissolve the different drugs were applied alone as controls. The results presented here are derived from 3–4 sets of independent experiments.