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Involvement of Endoplasmic Reticulum Stress, Autophagy, and Apoptosis in Advanced Glycation End Products-Induced Glomerular Mesangial Cell Injury

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ABSTRACT

Advanced glycation end-products (AGEs)-induced mesangial cell death is one of major causes of glomerulus dysfunction in diabetic nephropathy. Both endoplasmic reticulum (ER) stress and autophagy are adaptive responses in cells under environmental stress and participate in the renal diseases. The role of ER stress and autophagy in AGEs-induced mesangial cell death is still unclear. Here, we investigated the effect and mechanism of AGEs on glomerular mesangial cells. AGEs dose-dependently decreased mesangial cell viability and induced cell apoptosis. AGEs also induced ER stress signals in a time- and dose-dependent manner. Inhibition of ER stress with 4-phenylbutyric acid effectively inhibited the activation of eIF2α and CHOP signals and reversed AGEs-induced cell apoptosis. AGEs also activated LC-3 cleavage, increased Atg5 expression, and decreased p62 expression, which indicated the autophagy induction in mesangial cells. Inhibition of autophagy by Atg5 siRNAs transfection aggravated AGEs-induced mesangial cell apoptosis. Moreover, ER stress inhibition by 4-phenylbutyric acid significantly reversed AGEs-induced autophagy, but autophagy inhibition did not influence the AGEs-induced ER stress-related signals activation. These results suggest that AGEs induce mesangial cell apoptosis via an ER stress-triggered signaling pathway. Atg5-dependent autophagy plays a protective role. These findings may offer a new strategy against AGEs toxicity in the kidney.

No MeSH data available.


Effects of AGEs on autophagy-related protein expressions.Cells were treated with AGEs (20–160 μg/ml) for 24 h. BSA (160 μg/ml) was used as a negative control. The cleavage of LC3 and the protein expressions of Atg 5, beclin 1, and p62 were determined by Western blot. Data are presented as mean ± SEM of three independent experiments performed in duplicates. *P < 0.05 as compared to BSA-treated group.
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f5: Effects of AGEs on autophagy-related protein expressions.Cells were treated with AGEs (20–160 μg/ml) for 24 h. BSA (160 μg/ml) was used as a negative control. The cleavage of LC3 and the protein expressions of Atg 5, beclin 1, and p62 were determined by Western blot. Data are presented as mean ± SEM of three independent experiments performed in duplicates. *P < 0.05 as compared to BSA-treated group.

Mentions: Autophagy is also an important mechanism involved in different renal injuries. AGEs significantly increased LC3 cleavage (LC3-II/LC3-I ratio) and autophagy-related gene 5 (Atg5) protein expression in mesangial cells in a dose- and time-dependent manner (Figs 5 and 6A). The protein expression of beclin1 was not affected by AGEs treatment (Fig. 5). The p62 protein, which is one of downstream signals of autophagy, was also decreased after AGEs treatment in a dose- and time-dependent manner (Figs 5 and 6A). Furthermore, the time course of caspase-3 activation was similar with the expression of ER stress and autophagy-related proteins after AGEs treatment (Fig. 6B). These results suggest that AGEs accumulation in mesangial cells induces autophagy activity.


Involvement of Endoplasmic Reticulum Stress, Autophagy, and Apoptosis in Advanced Glycation End Products-Induced Glomerular Mesangial Cell Injury
Effects of AGEs on autophagy-related protein expressions.Cells were treated with AGEs (20–160 μg/ml) for 24 h. BSA (160 μg/ml) was used as a negative control. The cleavage of LC3 and the protein expressions of Atg 5, beclin 1, and p62 were determined by Western blot. Data are presented as mean ± SEM of three independent experiments performed in duplicates. *P < 0.05 as compared to BSA-treated group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5035926&req=5

f5: Effects of AGEs on autophagy-related protein expressions.Cells were treated with AGEs (20–160 μg/ml) for 24 h. BSA (160 μg/ml) was used as a negative control. The cleavage of LC3 and the protein expressions of Atg 5, beclin 1, and p62 were determined by Western blot. Data are presented as mean ± SEM of three independent experiments performed in duplicates. *P < 0.05 as compared to BSA-treated group.
Mentions: Autophagy is also an important mechanism involved in different renal injuries. AGEs significantly increased LC3 cleavage (LC3-II/LC3-I ratio) and autophagy-related gene 5 (Atg5) protein expression in mesangial cells in a dose- and time-dependent manner (Figs 5 and 6A). The protein expression of beclin1 was not affected by AGEs treatment (Fig. 5). The p62 protein, which is one of downstream signals of autophagy, was also decreased after AGEs treatment in a dose- and time-dependent manner (Figs 5 and 6A). Furthermore, the time course of caspase-3 activation was similar with the expression of ER stress and autophagy-related proteins after AGEs treatment (Fig. 6B). These results suggest that AGEs accumulation in mesangial cells induces autophagy activity.

View Article: PubMed Central - PubMed

ABSTRACT

Advanced glycation end-products (AGEs)-induced mesangial cell death is one of major causes of glomerulus dysfunction in diabetic nephropathy. Both endoplasmic reticulum (ER) stress and autophagy are adaptive responses in cells under environmental stress and participate in the renal diseases. The role of ER stress and autophagy in AGEs-induced mesangial cell death is still unclear. Here, we investigated the effect and mechanism of AGEs on glomerular mesangial cells. AGEs dose-dependently decreased mesangial cell viability and induced cell apoptosis. AGEs also induced ER stress signals in a time- and dose-dependent manner. Inhibition of ER stress with 4-phenylbutyric acid effectively inhibited the activation of eIF2&alpha; and CHOP signals and reversed AGEs-induced cell apoptosis. AGEs also activated LC-3 cleavage, increased Atg5 expression, and decreased p62 expression, which indicated the autophagy induction in mesangial cells. Inhibition of autophagy by Atg5 siRNAs transfection aggravated AGEs-induced mesangial cell apoptosis. Moreover, ER stress inhibition by 4-phenylbutyric acid significantly reversed AGEs-induced autophagy, but autophagy inhibition did not influence the AGEs-induced ER stress-related signals activation. These results suggest that AGEs induce mesangial cell apoptosis via an ER stress-triggered signaling pathway. Atg5-dependent autophagy plays a protective role. These findings may offer a new strategy against AGEs toxicity in the kidney.

No MeSH data available.