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Superoxide via Sp3 but Not NF‐Kb Regulates Renal AT1 Receptor Expression and Function in Human Kidney Cells
Author(s) -
Saleem Mohammad,
Asghar Mohammad
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.719.3
Subject(s) - superoxide , angiotensin ii , angiotensin ii receptor type 1 , chemistry , protein kinase c , receptor , microbiology and biotechnology , messenger rna , oxidative stress , nf κb , kidney , small hairpin rna , reactive oxygen species , transfection , medicine , endocrinology , signal transduction , biology , biochemistry , rna , enzyme , gene
Oxidative stress plays a causal role in higher Angiotensin II type 1 receptor (AT1R) function and hypertension. Both redox‐sensitive transcription factors have been implicated in regulation of AT1R. Here, we tested a hypothesis that superoxide but hydrogen peroxide (H 2 O 2 ) via Sp3 but not NF‐kB p‐65 transcription factor regulates renal AT1R. We tested our hypothesis in human kidney (HK2) cells by undertaking following studies. Diethyldithiocarbamate (DDC), a superoxide prodrug, but not H 2 O 2 increased nuclear accumulation of both Sp3 and NF‐kB in HK2 cells as measured by immunoblotting. Importantly, this effect was attenuated with Tempol, a superoxide mimetic. Further, DDC increased AT1R mRNA and protein levels that were attenuated with Tempol treatment, measured respectively by RT‐qPCR and immunoblotting. However, H 2 O 2 did not show any significant effect on AT1R mRNA and protein levels. Moreover, Sp3 plasmid increased while Sp3 siRNA decreased AT1R protein levels in HK2 cells. Interestingly, NF‐kB plasmid did not show any significant effect on AT1R protein levels. Moreover, NF‐kB shRNA and PDTC, an NF‐kB inhibitor, both increased AT1R mRNA, suggesting an inhibitory effect of NF‐kB on AT1R. In addition, DDC treatment showed an exaggerated response of Ang II on protein kinase C (PKC) activity, an indicator of AT1R function, which was attenuated with Tempol treatment. Collectively, our results suggest that superoxide but not H 2 O 2 via Sp3 but not NF‐kB up‐regulate AT1 receptor expression and function that may contribute to hypertension. Support or Funding Information NIH/NIA: AG039836