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

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 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 ER stress-related proteins at various time points.Cells were treated with AGEs (160 μg/ml) for 3, 6, 12, and 24 h. BSA (160 μg/ml) was used as a negative control. The protein expressions of GRP78, IRE-1α, phospho-eIF2α, phospho-JNK, and CHOP were determined by Western blot. Data are presented as mean ± SEM of three independent experiments performed in duplicates. *P < 0.05 as compared to control group. #P < 0.05 as compared to BSA-treated group.
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f4: Effects of AGEs on ER stress-related proteins at various time points.Cells were treated with AGEs (160 μg/ml) for 3, 6, 12, and 24 h. BSA (160 μg/ml) was used as a negative control. The protein expressions of GRP78, IRE-1α, phospho-eIF2α, phospho-JNK, and CHOP were determined by Western blot. Data are presented as mean ± SEM of three independent experiments performed in duplicates. *P < 0.05 as compared to control group. #P < 0.05 as compared to BSA-treated group.

Mentions: To understand whether ER stress involved in AGEs-induced mesangial cell apoptosis, ER stress-related proteins were detected by Western blots. Mesangial cells were treated with various concentrations of AGEs (20, 40, 80, and 160 μg/ml) and BSA (160 μg/ml) for 24 h. AGEs significantly upregulated the protein expressions of GRP78, ATF4, and CHOP and phosphorylation of eIF2α in a dose-dependent manner (Fig. 3). AGEs also increased the phosphorylations of eIF2α and c-Jun N-terminal kinase (JNK) and the protein expressions of GRP78, IRE-1α, and CHOP in a time dependent manner (Fig. 4). These results indicate that AGEs induced ER stress in mesangial cells, which may participate in AGEs-induced mesangial cell apoptosis.


Involvement of Endoplasmic Reticulum Stress, Autophagy, and Apoptosis in Advanced Glycation End Products-Induced Glomerular Mesangial Cell Injury
Effects of AGEs on ER stress-related proteins at various time points.Cells were treated with AGEs (160 μg/ml) for 3, 6, 12, and 24 h. BSA (160 μg/ml) was used as a negative control. The protein expressions of GRP78, IRE-1α, phospho-eIF2α, phospho-JNK, and CHOP were determined by Western blot. Data are presented as mean ± SEM of three independent experiments performed in duplicates. *P < 0.05 as compared to control group. #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

f4: Effects of AGEs on ER stress-related proteins at various time points.Cells were treated with AGEs (160 μg/ml) for 3, 6, 12, and 24 h. BSA (160 μg/ml) was used as a negative control. The protein expressions of GRP78, IRE-1α, phospho-eIF2α, phospho-JNK, and CHOP were determined by Western blot. Data are presented as mean ± SEM of three independent experiments performed in duplicates. *P < 0.05 as compared to control group. #P < 0.05 as compared to BSA-treated group.
Mentions: To understand whether ER stress involved in AGEs-induced mesangial cell apoptosis, ER stress-related proteins were detected by Western blots. Mesangial cells were treated with various concentrations of AGEs (20, 40, 80, and 160 μg/ml) and BSA (160 μg/ml) for 24 h. AGEs significantly upregulated the protein expressions of GRP78, ATF4, and CHOP and phosphorylation of eIF2α in a dose-dependent manner (Fig. 3). AGEs also increased the phosphorylations of eIF2α and c-Jun N-terminal kinase (JNK) and the protein expressions of GRP78, IRE-1α, and CHOP in a time dependent manner (Fig. 4). These results indicate that AGEs induced ER stress in mesangial cells, which may participate in AGEs-induced mesangial cell apoptosis.

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.