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Deficient dopamine D2 receptor function causes renal inflammation independently of high blood pressure.

Zhang Y, Cuevas S, Asico LD, Escano C, Yang Y, Pascua AM, Wang X, Jones JE, Grandy D, Eisner G, Jose PA, Armando I - PLoS ONE (2012)

Bottom Line: Genetic factors, including polymorphisms of the dopamine D(2) receptor gene (DRD2) are associated with essential hypertension, but the mechanisms of their contribution are incompletely understood.Our results demonstrate that the impact of decreased D(2)R function on renal inflammation is a primary effect, not necessarily associated with enhanced oxidant activity, or blood pressure; renal damage is the cause, not the result, of hypertension.Deficient renal D(2)R function may be of clinical relevance since common polymorphisms of the human DRD2 gene result in decreased D(2)R expression and function.

View Article: PubMed Central - PubMed

Affiliation: Division of Nephrology, Department of Medicine, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America.

ABSTRACT
Renal dopamine receptors participate in the regulation of blood pressure. Genetic factors, including polymorphisms of the dopamine D(2) receptor gene (DRD2) are associated with essential hypertension, but the mechanisms of their contribution are incompletely understood. Mice lacking Drd2 (D(2)-/-) have elevated blood pressure, increased renal expression of inflammatory factors, and renal injury. We tested the hypothesis that decreased dopamine D(2) receptor (D(2)R) function increases vulnerability to renal inflammation independently of blood pressure, is an immediate cause of renal injury, and contributes to the subsequent development of hypertension. In D(2)-/- mice, treatment with apocynin normalized blood pressure and decreased oxidative stress, but did not affect the expression of inflammatory factors. In mouse RPTCs Drd2 silencing increased the expression of TNFα and MCP-1, while treatment with a D(2)R agonist abolished the angiotensin II-induced increase in TNF-α and MCP-1. In uni-nephrectomized wild-type mice, selective Drd2 silencing by subcapsular infusion of Drd2 siRNA into the remaining kidney produced the same increase in renal cytokines/chemokines that occurs after Drd2 deletion, increased the expression of markers of renal injury, and increased blood pressure. Moreover, in mice with two intact kidneys, short-term Drd2 silencing in one kidney, leaving the other kidney undisturbed, induced inflammatory factors and markers of renal injury in the treated kidney without increasing blood pressure. Our results demonstrate that the impact of decreased D(2)R function on renal inflammation is a primary effect, not necessarily associated with enhanced oxidant activity, or blood pressure; renal damage is the cause, not the result, of hypertension. Deficient renal D(2)R function may be of clinical relevance since common polymorphisms of the human DRD2 gene result in decreased D(2)R expression and function.

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D2R function in moue renal proximal tubule cells A.Effect of silencing of D2R on the expression of pro-inflammatory cytokines/chemokines in mouse RPTCs. Cells were cultured to 60–70% confluence and transfected with non-silencing (NS siRNA) or Drd2 siRNA. After 48 h the cells were washed and lysed. Protein expression of D2R (55 kDa), TNFα (25 kDa), and MCP-1(17 kDa) was semi-quantified by immunoblotting. Inset shows one set of immunoblots. NFkB activation was analyzed via the transient expression of a NFkB-luciferase reporter system by reverse transfection Results are expressed as percentage of NS siRNA or fold activation compared to NS siRNA. *P<0.05 vs. NS (non-silencing) siRNA, n = 4/group. B. Effects of Ang II and D2R stimulation on TNFα and MCP-1 in mouse RPTCs. Cells were serum starved for 2 h before treatment for 24 h in serum-free medium with vehicle (PBS) or 100 nM Ang II, in the presence or absence of 1 μM quinpirole (D2R/D3R agonist) or 1 μM quinpirole plus 1 μM L-741,262 (D2R antagonist). Expression of TNFα (25 kDa) and MCP-1 (17 kDa) protein was semi-quantified by immunoblotting. Inset shows one set of immunoblots. Results were corrected for actin and expressed as % of vehicle. * P<0.05 vs. vehicle; n = 6/group.
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pone-0038745-g004: D2R function in moue renal proximal tubule cells A.Effect of silencing of D2R on the expression of pro-inflammatory cytokines/chemokines in mouse RPTCs. Cells were cultured to 60–70% confluence and transfected with non-silencing (NS siRNA) or Drd2 siRNA. After 48 h the cells were washed and lysed. Protein expression of D2R (55 kDa), TNFα (25 kDa), and MCP-1(17 kDa) was semi-quantified by immunoblotting. Inset shows one set of immunoblots. NFkB activation was analyzed via the transient expression of a NFkB-luciferase reporter system by reverse transfection Results are expressed as percentage of NS siRNA or fold activation compared to NS siRNA. *P<0.05 vs. NS (non-silencing) siRNA, n = 4/group. B. Effects of Ang II and D2R stimulation on TNFα and MCP-1 in mouse RPTCs. Cells were serum starved for 2 h before treatment for 24 h in serum-free medium with vehicle (PBS) or 100 nM Ang II, in the presence or absence of 1 μM quinpirole (D2R/D3R agonist) or 1 μM quinpirole plus 1 μM L-741,262 (D2R antagonist). Expression of TNFα (25 kDa) and MCP-1 (17 kDa) protein was semi-quantified by immunoblotting. Inset shows one set of immunoblots. Results were corrected for actin and expressed as % of vehicle. * P<0.05 vs. vehicle; n = 6/group.

Mentions: Mouse RPTCs in culture endogenously express D2R, TNFα, and MCP-1. Forty-eight hour-treatment with Drd2 siRNA decreased D2R protein expression by about 85%. The treatment increased NFkB transcriptional activity (3.5-fold) and about two-fold the expression of both TNFα, and MCP-1 which are downstream of NFkB (Figure 4A).


Deficient dopamine D2 receptor function causes renal inflammation independently of high blood pressure.

Zhang Y, Cuevas S, Asico LD, Escano C, Yang Y, Pascua AM, Wang X, Jones JE, Grandy D, Eisner G, Jose PA, Armando I - PLoS ONE (2012)

D2R function in moue renal proximal tubule cells A.Effect of silencing of D2R on the expression of pro-inflammatory cytokines/chemokines in mouse RPTCs. Cells were cultured to 60–70% confluence and transfected with non-silencing (NS siRNA) or Drd2 siRNA. After 48 h the cells were washed and lysed. Protein expression of D2R (55 kDa), TNFα (25 kDa), and MCP-1(17 kDa) was semi-quantified by immunoblotting. Inset shows one set of immunoblots. NFkB activation was analyzed via the transient expression of a NFkB-luciferase reporter system by reverse transfection Results are expressed as percentage of NS siRNA or fold activation compared to NS siRNA. *P<0.05 vs. NS (non-silencing) siRNA, n = 4/group. B. Effects of Ang II and D2R stimulation on TNFα and MCP-1 in mouse RPTCs. Cells were serum starved for 2 h before treatment for 24 h in serum-free medium with vehicle (PBS) or 100 nM Ang II, in the presence or absence of 1 μM quinpirole (D2R/D3R agonist) or 1 μM quinpirole plus 1 μM L-741,262 (D2R antagonist). Expression of TNFα (25 kDa) and MCP-1 (17 kDa) protein was semi-quantified by immunoblotting. Inset shows one set of immunoblots. Results were corrected for actin and expressed as % of vehicle. * P<0.05 vs. vehicle; n = 6/group.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3375266&req=5

pone-0038745-g004: D2R function in moue renal proximal tubule cells A.Effect of silencing of D2R on the expression of pro-inflammatory cytokines/chemokines in mouse RPTCs. Cells were cultured to 60–70% confluence and transfected with non-silencing (NS siRNA) or Drd2 siRNA. After 48 h the cells were washed and lysed. Protein expression of D2R (55 kDa), TNFα (25 kDa), and MCP-1(17 kDa) was semi-quantified by immunoblotting. Inset shows one set of immunoblots. NFkB activation was analyzed via the transient expression of a NFkB-luciferase reporter system by reverse transfection Results are expressed as percentage of NS siRNA or fold activation compared to NS siRNA. *P<0.05 vs. NS (non-silencing) siRNA, n = 4/group. B. Effects of Ang II and D2R stimulation on TNFα and MCP-1 in mouse RPTCs. Cells were serum starved for 2 h before treatment for 24 h in serum-free medium with vehicle (PBS) or 100 nM Ang II, in the presence or absence of 1 μM quinpirole (D2R/D3R agonist) or 1 μM quinpirole plus 1 μM L-741,262 (D2R antagonist). Expression of TNFα (25 kDa) and MCP-1 (17 kDa) protein was semi-quantified by immunoblotting. Inset shows one set of immunoblots. Results were corrected for actin and expressed as % of vehicle. * P<0.05 vs. vehicle; n = 6/group.
Mentions: Mouse RPTCs in culture endogenously express D2R, TNFα, and MCP-1. Forty-eight hour-treatment with Drd2 siRNA decreased D2R protein expression by about 85%. The treatment increased NFkB transcriptional activity (3.5-fold) and about two-fold the expression of both TNFα, and MCP-1 which are downstream of NFkB (Figure 4A).

Bottom Line: Genetic factors, including polymorphisms of the dopamine D(2) receptor gene (DRD2) are associated with essential hypertension, but the mechanisms of their contribution are incompletely understood.Our results demonstrate that the impact of decreased D(2)R function on renal inflammation is a primary effect, not necessarily associated with enhanced oxidant activity, or blood pressure; renal damage is the cause, not the result, of hypertension.Deficient renal D(2)R function may be of clinical relevance since common polymorphisms of the human DRD2 gene result in decreased D(2)R expression and function.

View Article: PubMed Central - PubMed

Affiliation: Division of Nephrology, Department of Medicine, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America.

ABSTRACT
Renal dopamine receptors participate in the regulation of blood pressure. Genetic factors, including polymorphisms of the dopamine D(2) receptor gene (DRD2) are associated with essential hypertension, but the mechanisms of their contribution are incompletely understood. Mice lacking Drd2 (D(2)-/-) have elevated blood pressure, increased renal expression of inflammatory factors, and renal injury. We tested the hypothesis that decreased dopamine D(2) receptor (D(2)R) function increases vulnerability to renal inflammation independently of blood pressure, is an immediate cause of renal injury, and contributes to the subsequent development of hypertension. In D(2)-/- mice, treatment with apocynin normalized blood pressure and decreased oxidative stress, but did not affect the expression of inflammatory factors. In mouse RPTCs Drd2 silencing increased the expression of TNFα and MCP-1, while treatment with a D(2)R agonist abolished the angiotensin II-induced increase in TNF-α and MCP-1. In uni-nephrectomized wild-type mice, selective Drd2 silencing by subcapsular infusion of Drd2 siRNA into the remaining kidney produced the same increase in renal cytokines/chemokines that occurs after Drd2 deletion, increased the expression of markers of renal injury, and increased blood pressure. Moreover, in mice with two intact kidneys, short-term Drd2 silencing in one kidney, leaving the other kidney undisturbed, induced inflammatory factors and markers of renal injury in the treated kidney without increasing blood pressure. Our results demonstrate that the impact of decreased D(2)R function on renal inflammation is a primary effect, not necessarily associated with enhanced oxidant activity, or blood pressure; renal damage is the cause, not the result, of hypertension. Deficient renal D(2)R function may be of clinical relevance since common polymorphisms of the human DRD2 gene result in decreased D(2)R expression and function.

Show MeSH
Related in: MedlinePlus