TY - JOUR
T1 - Inducible nitric oxide synthase and apoptosis in murine proximal tubule epithelial cells
AU - Tiwari, Manish M.
AU - Messer, Kurt J.
AU - Mayeux, Philip R.
N1 - Funding Information:
This research was supported by funds from the University of Arkansas for Medical Sciences Graduate Student Research Fund awarded to M.M. Tiwari, K.J. Messer was supported by an Institutional Summer Undergraduate Research Fellowship from the American Society for Pharmacology and Experimental Therapeutics.
PY - 2006/6
Y1 - 2006/6
N2 - Since inducible nitric oxide synthase (iNOS) and proximal tubule injury are known to be critical determinants of lipopolysaccharide (LPS)-induced renal failure, the role of nitric oxide (NO) in proximal tubule cell apoptosis was examined. An 18-h treatment with a combination of LPS (5 μg/ml) and interferon-γ (IFN-γ, 100 units/ml) synergistically induced iNOS and produced a 20-fold increase in NO generation in the TKPTS murine proximal tubule cell line. NO generation by LPS + IFN-γ was blocked by a specific iNOS blocker, L-N6-(1-iminoethyl)-lysine (L-NIL, 1mM). To assess the role of iNOS-derived NO in proximal tubule cell apoptosis, annexin V- and propidium iodide-labeled cells were analyzed by flow cytometry. Neither the induction of iNOS nor its inhibition produced significant apoptotic cell death in TKPTS cells. Two exogenous NO donors were used to examine the role of NO more directly in proximal tubule apoptosis. Although both sodium nitroprusside (SNP), an iron-containing, nitrosonium cation donor, and S-nitroso-N-acetylpenicillamine (SNAP), a noniron-containing, NO generator, produced a concentration-dependent increase in NO generation, only SNP increased apoptotic cell death in TKPTS cells (5.9 ± 0.7% in control cells vs. 21.6 ± 3.8% in SNP [500μM]-treated cells; n = 4-9; p < 0.01). SNP-mediated tubule cell apoptosis was not dependent on the activation of caspases or p53 but was possibly related to the generation of reactive oxygen species by SNP. Thus, in TKPTS cells induction of iNOS and generation of NO by LPS does not lead to tubular epithelial cell death.
AB - Since inducible nitric oxide synthase (iNOS) and proximal tubule injury are known to be critical determinants of lipopolysaccharide (LPS)-induced renal failure, the role of nitric oxide (NO) in proximal tubule cell apoptosis was examined. An 18-h treatment with a combination of LPS (5 μg/ml) and interferon-γ (IFN-γ, 100 units/ml) synergistically induced iNOS and produced a 20-fold increase in NO generation in the TKPTS murine proximal tubule cell line. NO generation by LPS + IFN-γ was blocked by a specific iNOS blocker, L-N6-(1-iminoethyl)-lysine (L-NIL, 1mM). To assess the role of iNOS-derived NO in proximal tubule cell apoptosis, annexin V- and propidium iodide-labeled cells were analyzed by flow cytometry. Neither the induction of iNOS nor its inhibition produced significant apoptotic cell death in TKPTS cells. Two exogenous NO donors were used to examine the role of NO more directly in proximal tubule apoptosis. Although both sodium nitroprusside (SNP), an iron-containing, nitrosonium cation donor, and S-nitroso-N-acetylpenicillamine (SNAP), a noniron-containing, NO generator, produced a concentration-dependent increase in NO generation, only SNP increased apoptotic cell death in TKPTS cells (5.9 ± 0.7% in control cells vs. 21.6 ± 3.8% in SNP [500μM]-treated cells; n = 4-9; p < 0.01). SNP-mediated tubule cell apoptosis was not dependent on the activation of caspases or p53 but was possibly related to the generation of reactive oxygen species by SNP. Thus, in TKPTS cells induction of iNOS and generation of NO by LPS does not lead to tubular epithelial cell death.
KW - Apoptosis
KW - Nitric oxide
KW - Proximal tubule
KW - S-nitroso-N-acetylpenicillamine
KW - Sodium nitroprusside
KW - iNOS
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U2 - 10.1093/toxsci/kfj168
DO - 10.1093/toxsci/kfj168
M3 - Article
C2 - 16551643
AN - SCOPUS:33744785413
SN - 1096-6080
VL - 91
SP - 493
EP - 500
JO - Toxicological Sciences
JF - Toxicological Sciences
IS - 2
ER -