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Macrophage-stimulating protein attenuates hydrogen peroxide-induced apoptosis in human renal HK-2 cells
Ko Eun Lee1, Eun Young Kim, Chang Seong Kim
1Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Republic of Korea.
Abstract:
Macrophage-stimulating protein (MSP) and its receptor, recepteur d'origine nantais (RON), play an important role in cell proliferation and migration. We have investigated the role of MSP in hydrogen peroxide (H2O2)-induced renal tubular apoptosis. Human renal proximal tubular (HK-2) cells were incubated with H2O2 for 24h in the presence of different concentrations of MSP, and cell viability was measured by MTT assay. The protein expression of Bax, Bcl-2, caspase-3, mitogen-activated protein kinases (MAPKs), phosphatidylinositol-3-kinase (PI3K)/Akt, and nuclear factor-kappa B (NF-κB) was determined by semiquantitative immunoblotting. Apoptosis was assessed by flow cytometry analysis after HK-2 cells were stained with fluorescein isothiocyanate-conjugated annexin V protein and propidium iodide. H2O2 treatment decreased cell viability in HK-2 cells; this was counteracted by MSP pretreatment. H2O2 treatment induced an increased ratio of Bax/Bcl-2, cleaved caspase-3, and the number of condensed nuclei, which was also counteracted by MSP. Flow cytometry analysis showed H2O2-induced apoptosis, and its prevention by MSP treatment. Increased protein expression of phospho-p38 MAPK was attenuated by MSP, while phospho-extracellular signal-regulated kinase and c-Jun-N-terminal kinase were not affected. H2O2 induced NF-κB activation and IκB-α degradation, but the increased nuclear NF-κB activation was counteracted by MSP or by a p38 MAPK inhibitor. H2O2 treatment decreased expression of phospho-PI3K and phospho-Akt, which was reversed by MSP pretreatment. These findings suggest that MSP attenuates H2O2-induced apoptosis in HK-2 cells by modulating the p38 and NF-κB, as well as PI3K/Akt, signaling pathways.
Insights
Macrophage-stimulating protein (MSP) protects kidney cells from hydrogen peroxide (H2O2)-induced apoptosis. MSP modulates key signaling pathways including p38 MAPK, NF-κB, and PI3K/Akt to prevent cell death.
Area of Science:
- Cell Biology
- Molecular Biology
- Renal Physiology
Background:
- Macrophage-stimulating protein (MSP) and its receptor (RON) are crucial for cell proliferation and migration.
- Hydrogen peroxide (H2O2) is implicated in inducing renal tubular apoptosis.
- Understanding MSP's role in mitigating H2O2-induced kidney cell damage is vital.
Purpose of the Study:
- To investigate the protective role of MSP against H2O2-induced apoptosis in human renal proximal tubular (HK-2) cells.
- To elucidate the specific signaling pathways modulated by MSP during H2O2 exposure.
Main Methods:
- HK-2 cells were treated with H2O2 and varying concentrations of MSP.
- Cell viability was assessed using MTT assays.
- Protein expression of apoptosis markers (Bax, Bcl-2, caspase-3) and signaling molecules (MAPKs, PI3K/Akt, NF-κB) was analyzed via immunoblotting.
- Apoptosis was quantified using Annexin V/propidium iodide staining and flow cytometry.
Main Results:
- MSP pretreatment significantly counteracted H2O2-induced decrease in HK-2 cell viability.
- MSP reduced the Bax/Bcl-2 ratio, cleaved caspase-3, and nuclear condensation, indicative of reduced apoptosis.
- MSP attenuated H2O2-induced activation of p38 MAPK and NF-κB, while reversing the downregulation of PI3K/Akt signaling.
Conclusions:
- MSP demonstrates a protective effect against H2O2-induced apoptosis in renal tubular cells.
- MSP exerts its protective function by modulating the p38 MAPK, NF-κB, and PI3K/Akt signaling pathways.
- These findings highlight MSP as a potential therapeutic target for preventing oxidative stress-related kidney injury.
