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Abstract: SA-PO783

Increased Dopamine D1 Receptor (D1R) Phosphorylation due to G Protein-Coupled Receptor Kinase 4 (GRK4) Variant 65L Causes Hypertension

Session Information

  • Hypertension and CVD: Mechanisms
    November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Hypertension and CVD

  • 1503 Hypertension and CVD: Mechanisms

Authors

  • Moore, Shaun Christopher, The George Washington University, Washington, District of Columbia, United States
  • Yaqub, Daniel A., The George Washington University, Washington, District of Columbia, United States
  • Asico, Laureano D., The George Washington University, Washington, District of Columbia, United States
  • Armando, Ines, The George Washington University, Washington, District of Columbia, United States
  • Jose, Pedro A., The George Washington University, Washington, District of Columbia, United States
Background

Activating variants of the human GRK4 (65R>L, 142A>V, and 486A>V) are involved in the desensitization of the D1R and are associated with hypertension in several ethnic groups. Although GRK4 is essential for the normal desensitization and resensitization of dopamine receptors, certain constitutively active GRK4 variants impairs dopamine D1 (D1R) function and natriuretic function. We have reported that global transgenic mice expressing hGRK4 65L have salt-sensitive hypertension.

Methods

We have reported that global transgenic mice expressing hGRK4 65L have salt-sensitive hypertension. To avoid the effect of protein overexpression in these transgenic mice, we generated mice globally expressing hGRK4 65L or hGRK4 wild type (WT) by crispr-cas9-mediated genome editing in C57Bl/6 mice (hGRK4 65L GE and hGRK4 WT GE)

Results

Systolic blood pressure (SBP) in hGRK4 65L GE mice under pentobarbital anesthesia was higher (124±2 vs 101±1 mmHg, n=5/group, P<0.05) than in their littermates not expressing the human gene (GE WT) or mice expressing hGRK4 WT GE . Renal D1R phosphorylation was higher in hGRK4 65L GE than GE WT (112±2 vs 100±1%, n=3/group, P<0.05). To determine the role of the kidney in the salt sensitivity of these mice, we generated mice with kidney-specific (KS) expression of the GRK4 65L (KS hGRK4 65L) by the bilateral ureteral infusion of adeno-associated virus (AAV) vectors carrying hGRK4 65L in GRK4 knockout mice. Mice infused with hGRK4 WT served as controls (KS hGRK4 WT). SBP (under anesthesia) before AAV was similar in both groups. SBP post AAV increased in KS hGRK4 65L (93±1 vs 117±4 mm Hg, P<0.05, n=4) but not in KS hGRK4 WT (96±2 vs 105±6, n=5). Renal D1R phosphorylation was higher (170 ± 10 vs 100 ±15%; n=5, P<0.02) in KS hGRK4 65L than KS hGRK4 WT. We also studied human renal proximal tubule cells (hRPTCs) endogenously carrying GRK4 WT or GRK4 65L. In hRPTCs with GRK4 65L D1R, phosphorylation (204 ± 22 vs 100±24%, n=6/group; P<0.05), was increased, relative to hRPTCs with GRK4 WT.

Conclusion

Our results show across different mouse models and hRPTCs that the presence of GRK4 65L results in increased D1R phosphorylation and show the vital role of renal D1R in the regulation of blood pressure.

Funding

  • NIDDK Support