BACKGROUND/AIMS: Klotho is a multifunctional protein expressed predominantly in kidney tubular epithelium. Here, we investigated the protective effects of Klotho on necroptosis in renal ischemic-reperfusion injury (IRI) and the role of oxidative stress in this process. METHODS: Mice were subjected to bilateral renal pedicle clamping. Mouse renal tubular epithelial (TCMK-1) cells were exposed to hypoxia/reoxygenation (H/R) or H2O2. Kidney samples from acute kidney injury (AKI) patients and controls were examined by immunofluorescence. Klotho protein and N-acetyl-L-cysteine (NAC) were used to define their roles in mediating necroptosis. Necroptosis was assessed by TUNEL staining, immunoblotting, and real-time PCR. Oxidative stress was studied via ELISA, immunoblotting, colorimetric, and thiobarbituric acid reactive substances assays. RESULTS: Renal IRI induced Klotho deficiency in the serum and kidney, but an increase in the urine. The levels of the necroptotic markers receptor-interacting protein kinase (RIP) 1, RIP3, IL-1β, and TUNEL-positive cells increased after IRI; all increases were ameliorated by Klotho. In TCMK-1 cells, Klotho and NAC attenuated the elevation in RIP1, RIP3, and LDH release induced by H/R or H2O2. Moreover, Klotho decreased the levels of oxidative stress biomarkers and elevated superoxide dismutase 2 expression in both in vivo and in vitro experiments. Studies in human samples further confirmed the Klotho deficiency and increased formation of RIP3 puncta in AKI kidneys. CONCLUSION: Klotho protects tubular epithelial cells from IRI and its anti-necroptotic role may be associated with oxidative stress inhibition.
BACKGROUND/AIMS: Klotho is a multifunctional protein expressed predominantly in kidney tubular epithelium. Here, we investigated the protective effects of Klotho on necroptosis in renal ischemic-reperfusion injury (IRI) and the role of oxidative stress in this process. METHODS:Mice were subjected to bilateral renal pedicle clamping. Mouse renal tubular epithelial (TCMK-1) cells were exposed to hypoxia/reoxygenation (H/R) or H2O2. Kidney samples from acute kidney injury (AKI) patients and controls were examined by immunofluorescence. Klotho protein and N-acetyl-L-cysteine (NAC) were used to define their roles in mediating necroptosis. Necroptosis was assessed by TUNEL staining, immunoblotting, and real-time PCR. Oxidative stress was studied via ELISA, immunoblotting, colorimetric, and thiobarbituric acid reactive substances assays. RESULTS: Renal IRI induced Klothodeficiency in the serum and kidney, but an increase in the urine. The levels of the necroptotic markers receptor-interacting protein kinase (RIP) 1, RIP3, IL-1β, and TUNEL-positive cells increased after IRI; all increases were ameliorated by Klotho. In TCMK-1 cells, Klotho and NAC attenuated the elevation in RIP1, RIP3, and LDH release induced by H/R or H2O2. Moreover, Klotho decreased the levels of oxidative stress biomarkers and elevated superoxide dismutase 2 expression in both in vivo and in vitro experiments. Studies in human samples further confirmed the Klothodeficiency and increased formation of RIP3 puncta in AKI kidneys. CONCLUSION:Klotho protects tubular epithelial cells from IRI and its anti-necroptotic role may be associated with oxidative stress inhibition.
Authors: Nema A Soliman; Muhammad T Abdel Ghafar; Norhan A AbuoHashish; Marwa A Ibrahim; Asmaa M Eid; Rehab M El-Gohary; Rehab E Abo El Gheit; Amira M Elshamy Journal: Neurochem Res Date: 2022-10-15 Impact factor: 4.414