Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10766892 | Biochemical and Biophysical Research Communications | 2008 | 7 Pages |
Abstract
Renal ischemia-reperfusion (I/R) injury is inevitable in transplantation, and it results in renal tubular epithelial cells undergoing cell death. We observed an increase in autophagosomes in the tubular epithelial cells of I/R-injured mouse models, and in biopsy specimens from human transplanted kidney. However, it remains unclear whether autophagy functions as a protective pathway, or contributes to I/R-induced cell death. Here, we employed the human renal proximal tubular epithelial cell line HK-2 in order to explore the role of autophagy under hypoxia (1% O2) or activation of reactive oxygen species (500 μM H2O2). When compared to normoxic conditions, 48 h of hypoxia slightly increased LC3-labeled autophagic vacuoles and markedly increased LAMP2-labeled lysosomes. We observed similar changes in the mouse IR-injury model. We then assessed autophagic generation and degradation by inhibiting the downstream lysosomal degradation of autophagic vacuoles using lysosomal protease inhibitor. We found that autophagosomes increased markedly under hypoxia in the presence of lysosomal protease inhibitors, thus suggesting that hypoxia induces high turnover of autophagic generation and degradation. Furthermore, inhibition of autophagy significantly inhibited H2O2-induced cell death. In conclusion, high turnover of autophagy may lead to autophagic cell death during I/R injury.
Related Topics
Life Sciences
Biochemistry, Genetics and Molecular Biology
Biochemistry
Authors
Chigure Suzuki, Yoshitaka Isaka, Yoshitsugu Takabatake, Hirotaka Tanaka, Masato Koike, Masahiro Shibata, Yasuo Uchiyama, Shiro Takahara, Enyu Imai,