Abstract P087: PDI via Keap1/Nrf2 Pathway Regulates Renal AT1 Receptors and Blood Pressure in Aging Rats
Renal angiotensin AT1 receptor (AT1R) plays pivotal role in the regulation of blood pressure (BP). We recently reported that age-associated oxidative stress causes hyper-activation of AT1R and hypertension in the aging Fischer Brown Norway (FBN) rats. Our objective was to understand the mechanism of higher oxidative stress contributing to the impaired AT1R function in the aged FBNs. Nrf2 transcription factor protects kidney from oxidative stress by activating the transcription of diverse antioxidant and detoxifying enzymes. Kelch-like ECH-associated protein 1 (keap1) inhibit Nrf2 activity by sequestering Nrf2 in cytosol. We hypothesize that protein disulfide isomerase (PDI), an enzyme involved in isomerization reaction, regulates keap1 and Nrf2. Nrf2, keap1 and PDI were determined by Western blotting and/or immunohistochemistry in the kidney of FBNs and human kidney 2 (HK2) cells. We found that the aging kidney had low levels of PDI (adult vs old: 5.38±2.60 vs 3.59±1.76, 33.3% decrease), which was associated with low nuclear levels of Nrf2 (adult vs old: 1.86±0.69 vs 0.87±0.18, 53.2% decrease) and high cytosolic levels of keap1 (adult vs old: 1.80±0.46 vs 2.40±0.49, 33.3% increase) in the aging FBNs. Moreover, PDI inhibition by bacitracin in HK2 cells significantly reduced Nrf2 accumulation (control vs treated: 1.25±0.26 vs 0.50±0.14, 60% decrease) in the nuclei. PDI siRNA treatment in HK2 cells decreased the level of PDI (scrambled vs PDI siRNA: 0.64±0.07 vs 0.52±0.08) while increased the level of AT1R (scramble vs PDI siRNA: 0.11 vs 0.20). These data suggest that PDI by regulating keap1/Nrf2 redox-pathway regulates AT1R, and may be involved in BP regulation in the aging FBNs.
Author Disclosures: X. Wang: None. M. Asghar: None.
- © 2015 by American Heart Association, Inc.