The regulatory role of dopamine receptor D1 on PP2A via SUMO-1 modification.

OBJECTIVE: Renal dopamine receptor D1 played a critical role in the regulation of body blood pressure. Under hypertension, over-phosphorylation of D1 receptor impaired its function. G protein kinase 4 (GRK4) and protein phosphatase 2A (PP2A) exerted the effect to phosphorylate and de-phosphorylate D1 receptor. A current study revealed that the inhibition of GRK4 cannot normalize the phosphorylation level of D1 receptor. Meanwhile, the PP2A was activated under hypertension, indicating abnormal de-phosphorylation function of D1 receptor, the reason for which remains unknown. This study aimed to investigate the effect and mechanism of SUMO-1 modification on the regulation of dopamine receptor D1 to PP2A.

MATERIALS AND METHODS: Bioinformatics software predicted SUMO modification site in dopamine receptor D1. Cultured CHO cells were transfected with mutants of renal dopamine receptor D1. Co-immunoprecipitation and Western blot tested the interaction between over-phosphorylated D1 receptor and PP2A. Laser confocal microscopy examined their co-localization.

RESULTS: Bioinformatics predicted two SUMO modification sites K265 and K402 in dopamine receptor D1. Co-immunoprecipitation assay revealed weakened interaction between PP2A and phosphorylated D1 receptor, impeding the de-phosphorylation and normal function of D1 receptor.

CONCLUSIONS: Two SUMO modification sites existed in dopamine receptor D1, the phosphorylation of which, due to SUMO modification, can interact with PP2A, leading to the inhibition of D1 de-phosphorylation and normal function, thus providing new insights for treatment and prevention of hypertension.