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Ras activation modulates methylglyoxal-induced mesangial cell apoptosis through superoxide production
Wei Jan Huang1, Chun Wu Tung, Cheng Ho
1Chiayi Campus, Chang Gung Institute of Technology, Pu-tzu City, Chiayi, Taiwan.
Aims:
While previous studies have demonstrated that diabetic nephropathy is attributable to glucose-derived dicarbonyl compounds, methylglyoxal (MGO)-inducing apoptosis in renal mesangial cells, the molecular mechanism of upper stream redox signaling modulation, has not been fully elucidated.
Methods:
Rat mesangial cells pretreated with or without superoxide dismutase, diphenyloniodium, SB203580, and manumycin A were cultured in methylglyoxal stress-induced apoptosis. Signaling protein expression, flow cytometry, and morphological features of apoptotic cell death were assessed.
Results:
Methylglyoxal decreased cell viability in mesangial cells. Superoxide mediated methylglyoxal-induced caspase 3 cleavage. Pretreatment with diphenyloniodium, SB203580, and manumycin A reduced methylglyoxal augmentation of superoxide synthesis and caspase-3 activation. Methylglyoxal rapidly enhanced Ras activation and progressively increased cytosolic P38 and nuclear c-Jun activation. Scavenging of superoxide by superoxide dismutase or diphenyloniodium, inhibiting P38 by SB203580, and inhibiting Ras with manumycin A successfully reduced the promoting effect of methylglyoxal on P38 and c-Jun phosphorylation (activation). Furthermore, pretreatment with superoxide dismutase, diphenyloniodium, SB203580, and manumycin A significantly attenuated methylglyoxal induction of apoptosis on the basis of Annexin-V assay and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labelling (TUNEL) staining.
Conclusions:
This study has shown that methylglyoxal increased Ras modulation of superoxide-mediated P38 activation and c-Jun activation, which resulted in increased apoptosis.
Insights
Methylglyoxal induces apoptosis in kidney cells by activating Ras and superoxide-mediated P38/c-Jun pathways. Inhibiting these pathways protects against methylglyoxal-induced cell death, offering potential therapeutic targets for diabetic nephropathy.
Area of Science:
- Nephrology
- Molecular Biology
- Cell Biology
Background:
- Diabetic nephropathy is linked to methylglyoxal (MGO), a dicarbonyl compound.
- MGO induces apoptosis in renal mesangial cells, but upstream redox signaling is unclear.
Purpose of the Study:
- Elucidate the molecular mechanism of methylglyoxal-induced apoptosis in renal cells.
- Investigate the role of redox signaling, specifically Ras, superoxide, P38, and c-Jun pathways.
Main Methods:
- Rat mesangial cells were treated with methylglyoxal and inhibitors (superoxide dismutase, diphenyloniodium, SB203580, manumycin A).
- Assessed cell viability, apoptosis (Annexin-V, TUNEL), and activation of signaling proteins (Ras, P38, c-Jun, caspase-3).
Main Results:
- Methylglyoxal reduced cell viability and induced apoptosis.
- Superoxide mediated MGO-induced caspase-3 cleavage.
- Inhibitors of superoxide, Ras, and P38 attenuated MGO-induced apoptosis and signaling pathway activation.
- MGO enhanced Ras activation, leading to superoxide-mediated P38 and c-Jun activation.
Conclusions:
- Methylglyoxal triggers apoptosis in renal mesangial cells via Ras-modulated, superoxide-dependent activation of P38 and c-Jun.
- Targeting these pathways may offer a strategy to mitigate MGO-induced kidney damage in diabetic nephropathy.
