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Aims: Reactive oxygen species are highly reactive molecules generated in different subcellular compartments. Both the dopamine D5 receptor (D5R) and endoplasmic reticulum (ER)-resident peroxiredoxin-4 (PRDX4) play protective roles against oxidative stress. This study is aimed at investigating the interaction between PRDX4 and D5R in regulating oxidative stress in the kidney. Results: Fenoldopam (FEN), a D1R and D5R agonist, increased PRDX4 protein expression, mainly in non-lipid rafts, in D5R-HEK 293 cells. FEN increased the co-immunoprecipitation of D5R and PRDX4 and their colocalization, particularly in the ER. The efficiency of Förster resonance energy transfer was increased with FEN treatment measured with fluorescence lifetime imaging microscopy. Silencing of PRDX4 increased hydrogen peroxide production, impaired the inhibitory effect of FEN on hydrogen peroxide production, and increased the production of interleukin-1β, tumor necrosis factor (TNF), and caspase-12 in renal cells. Furthermore, in Drd5−/− mice, which are in a state of oxidative stress, renal cortical PRDX4 was decreased whereas interleukin-1β, TNF, and caspase-12 were increased, relative to their normotensive wild-type Drd5+/+ littermates. Innovation: Our findings demonstrate a novel relationship between D5R and PRDX4 and the consequent effects of this relationship in attenuating hydrogen peroxide production in the ER and the production of proinflammatory cytokines. This study provides the potential for the development of biomarkers and new therapeutics for renal inflammatory disorders, including hypertension. Conclusion: PRDX4 interacts with D5R to decrease oxidative stress and inflammation in renal cells that may have the potential for translational significance. Antioxid. Redox Signal. 38, 1150–1166. [ABSTRACT FROM AUTHOR]

Effective receptor signaling is anchored on the preferential localization of the receptor in lipid rafts, which are plasma membrane platforms replete with cholesterol and sphingolipids. We hypothesized that the dopamine D1 receptor (D1R) contains structural features that allow it to reside in lipid rafts for its activity. Mutation of C347 palmitoylation site and Y218 of a newly identified Cholesterol Recognition Amino Acid Consensus motif resulted in the exclusion of D1R from lipid rafts, blunted cAMP response, impaired sodium transport, and increased oxidative stress in renal proximal tubule cells (RPTCs). Kidney‐restricted silencing of Drd1 in C57BL/6J mice increased blood pressure (BP) that was normalized by renal tubule‐restricted rescue with D1R‐wild‐type but not the mutant D1R 347A that lacks a palmitoylation site. Kidney‐restricted disruption of lipid rafts by β‐MCD jettisoned the D1R from the brush border, decreased sodium excretion, and increased oxidative stress and BP in C57BL/6J mice. Deletion of the PX domain of the novel D1R‐binding partner sorting nexin 19 (SNX19) resulted in D1R partitioning solely to non‐raft domains, while silencing of SNX19 impaired D1R function in RPTCs. Kidney‐restricted silencing of Snx19 resulted in hypertension in C57BL/6J mice. Our results highlight the essential role of lipid rafts for effective D1R signaling. [ABSTRACT FROM AUTHOR]