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In Vitro and In Vivo Detection of Mitophagy in Human Cells, C. Elegans, and Mice
Published on: November 22, 2017
Microcystin-LR-Exposure-Induced Kidney Damage by Inhibiting MKK6-Mediated Mitophagy in Mice
Xueqiong Yao1, Ying Liu1, Yue Yang2
1Department of Epidemiology and Health Statistics, The Key Laboratory of Typical Environmental Pollution and Health Hazards of Hunan Province, School of Basic Medicine, School of Public Health, Hengyang Medical School, University of South China, Hengyang 421001, China.
Abstract:
Previous studies have reported that microcystin-LR (MC-LR) levels are highly correlated with abnormal renal function indicators, suggesting that MC-LR is an independent risk factor for kidney damage. However, the evidence for the exact regulation mechanism of MC-LR on kidney damage is still limited, and further in-depth exploration is needed. In addition, the mitochondria-related mechanism of MC-LR leading to kidney damage has not been elucidated. To this end, the present study aimed to further explore the mechanism of mitophagy related to kidney damage induced by MC-LR through in vitro and in vivo experiments. Male C57BL/6 mice were fed with a standard rodent pellet and exposed daily to MC-LR (20 μg/kg·bw) via intraperitoneal injections for 7 days. Moreover, HEK 293 cells were treated with MC-LR (20 μM) for 24 h. The histopathological results exhibited kidney damage after MC-LR exposure, characterized by structurally damaged nephrotomies, with inflammatory cell infiltration. Similarly, a significant increase in renal interstitial fibrosis was observed in the kidneys of MC-LR-treated mice compared with those of the control group (CT) mice. MC-LR exposure caused impaired kidney function, with markedly increased blood urea nitrogen (BUN), creatinine (Cr), and uric acid (UA) levels in mice. Ultrastructural analysis exhibited obviously swollen, broken, and disappearing mitochondrial crests, and partial mitochondrial vacuoles in the MC-LR-treated HEK 293 cells. The Western blotting results demonstrated that exposure to MC-LR significantly increased the protein expressions of MKK6, p-p38, and p62, while the expression of mitophagy-related proteins was significantly inhibited in the kidneys of mice and HEK293 cells, including parkin, TOM20, and LC3-II, indicating the inhibition of mitophagy. Therefore, our data suggest that the inhibition of MKK6-mediated mitophagy might be the toxicological mechanism of kidney toxicity in mice with acute exposure to MC-LR.
Insights
Microcystin-LR (MC-LR) causes kidney damage by inhibiting mitophagy, a crucial cellular cleaning process. This study reveals MKK6-mediated mitophagy inhibition as a key toxicological mechanism in acute MC-LR kidney injury.
Area of Science:
- Toxicology
- Cell Biology
- Renal Physiology
Background:
- Microcystin-LR (MC-LR) is linked to kidney dysfunction.
- The precise mechanisms of MC-LR-induced kidney damage, particularly mitochondrial involvement, remain unclear.
Purpose of the Study:
- To investigate the role of mitophagy in MC-LR-induced kidney damage.
- To elucidate the molecular mechanisms underlying MC-LR nephrotoxicity.
Main Methods:
- In vivo study: Mice exposed to MC-LR daily for 7 days.
- In vitro study: HEK 293 cells treated with MC-LR.
- Histopathology, blood biochemistry (BUN, Cr, UA), ultrastructural analysis, and Western blotting were performed.
Main Results:
- MC-LR exposure induced kidney damage, interstitial fibrosis, and impaired renal function in mice.
- Mitochondrial damage (swelling, crest disruption, vacuoles) observed in MC-LR-treated cells.
- MC-LR inhibited mitophagy, evidenced by altered protein expressions (increased MKK6, p-p38, p62; decreased parkin, TOM20, LC3-II).
Conclusions:
- MC-LR exposure leads to significant kidney damage and dysfunction.
- Inhibition of MKK6-mediated mitophagy is a primary mechanism of MC-LR nephrotoxicity.
