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The role of hypoxia-inducible factor-1 α in zinc oxide nanoparticle-induced nephrotoxicity in vitro and in vivo

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ABSTRACT

Background: Zinc oxide nanoparticles (ZnO NPs) are used in an increasing number of products, including rubber manufacture, cosmetics, pigments, food additives, medicine, chemical fibers and electronics. However, the molecular mechanisms underlying ZnO NP nephrotoxicity remain unclear. In this study, we evaluated the potential toxicity of ZnO NPs in kidney cells in vitro and in vivo.

Results: We found that ZnO NPs were apparently engulfed by the HEK-293 human embryonic kidney cells and then induced reactive oxygen species (ROS) generation. Furthermore, exposure to ZnO NPs led to a reduction in cell viability and induction of apoptosis and autophagy. Interestingly, the ROS-induced hypoxia-inducible factor-1α (HIF-1α) signaling pathway was significantly increased following ZnO NPs exposure. Additionally, connective tissue growth factor (CTGF) and plasminogen activator inhibitor-1 (PAI-1), which are directly regulated by HIF-1 and are involved in the pathogenesis of kidney diseases, displayed significantly increased levels following ZnO NPs exposure in HEK-293 cells. HIF-1α knockdown resulted in significantly decreased levels of autophagy and increased cytotoxicity. Therefore, our results suggest that HIF-1α may have a protective role in adaptation to the toxicity of ZnO NPs in kidney cells. In an animal study, fluorescent ZnO NPs were clearly observed in the liver, lungs, kidneys, spleen and heart. ZnO NPs caused histopathological lesions in the kidney and increase in serum creatinine and blood urea nitrogen (BUN) which indicate possible renal possible damage. Moreover, ZnO NPs enhanced the HIF-1α signaling pathway, apoptosis and autophagy in mouse kidney tissues.

Conclusions: ZnO NPs may cause nephrotoxicity, and the results demonstrate the importance of considering the toxicological hazards of ZnO NP production and application, especially for medicinal use.

Electronic supplementary material: The online version of this article (doi:10.1186/s12989-016-0163-3) contains supplementary material, which is available to authorized users.

No MeSH data available.


Effects of ZnO NPs on cellular ROS and the expression of HIF-1α-related proteins in HEK-293 cells. a ROS generation in HEK-293 cells treated with ZnO NPs for 1, 3 or 5 h and with DCFH-DA for an additional 30 min. The fluorescence in the cells was immediately analyzed using a fluorescence microplate reader. b Western blotting for HIF-1α, PAI-1 and CTGF in HEK-293 cells. The cells were treated with ZnO NPs for 24 h
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Fig2: Effects of ZnO NPs on cellular ROS and the expression of HIF-1α-related proteins in HEK-293 cells. a ROS generation in HEK-293 cells treated with ZnO NPs for 1, 3 or 5 h and with DCFH-DA for an additional 30 min. The fluorescence in the cells was immediately analyzed using a fluorescence microplate reader. b Western blotting for HIF-1α, PAI-1 and CTGF in HEK-293 cells. The cells were treated with ZnO NPs for 24 h

Mentions: ZnO NPs may cause oxidative stress resulting in lipid peroxidation, cell membrane damage and, ultimately, cell death or apoptosis in macrophages and human cells [36]. We determined the intracellular ROS level by DCFH-DA (Fig. 2a). The results showed that ZnO NPs stimulated ROS formation in cells in a concentration-dependent manner. It has been reported that ROS induce HIF-1α activation [37]. HIF-1α is involved in the pathogenesis of kidney diseases, as are PAI-1 and CTGF [8]. As shown in Fig. 2b, the expression of HIF-1α, PAI-1 and CTGF significantly increased following ZnO NP exposure.Fig. 2


The role of hypoxia-inducible factor-1 α in zinc oxide nanoparticle-induced nephrotoxicity in vitro and in vivo
Effects of ZnO NPs on cellular ROS and the expression of HIF-1α-related proteins in HEK-293 cells. a ROS generation in HEK-293 cells treated with ZnO NPs for 1, 3 or 5 h and with DCFH-DA for an additional 30 min. The fluorescence in the cells was immediately analyzed using a fluorescence microplate reader. b Western blotting for HIF-1α, PAI-1 and CTGF in HEK-293 cells. The cells were treated with ZnO NPs for 24 h
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5037597&req=5

Fig2: Effects of ZnO NPs on cellular ROS and the expression of HIF-1α-related proteins in HEK-293 cells. a ROS generation in HEK-293 cells treated with ZnO NPs for 1, 3 or 5 h and with DCFH-DA for an additional 30 min. The fluorescence in the cells was immediately analyzed using a fluorescence microplate reader. b Western blotting for HIF-1α, PAI-1 and CTGF in HEK-293 cells. The cells were treated with ZnO NPs for 24 h
Mentions: ZnO NPs may cause oxidative stress resulting in lipid peroxidation, cell membrane damage and, ultimately, cell death or apoptosis in macrophages and human cells [36]. We determined the intracellular ROS level by DCFH-DA (Fig. 2a). The results showed that ZnO NPs stimulated ROS formation in cells in a concentration-dependent manner. It has been reported that ROS induce HIF-1α activation [37]. HIF-1α is involved in the pathogenesis of kidney diseases, as are PAI-1 and CTGF [8]. As shown in Fig. 2b, the expression of HIF-1α, PAI-1 and CTGF significantly increased following ZnO NP exposure.Fig. 2

View Article: PubMed Central - PubMed

ABSTRACT

Background: Zinc oxide nanoparticles (ZnO NPs) are used in an increasing number of products, including rubber manufacture, cosmetics, pigments, food additives, medicine, chemical fibers and electronics. However, the molecular mechanisms underlying ZnO NP nephrotoxicity remain unclear. In this study, we evaluated the potential toxicity of ZnO NPs in kidney cells in vitro and in vivo.

Results: We found that ZnO NPs were apparently engulfed by the HEK-293 human embryonic kidney cells and then induced reactive oxygen species (ROS) generation. Furthermore, exposure to ZnO NPs led to a reduction in cell viability and induction of apoptosis and autophagy. Interestingly, the ROS-induced hypoxia-inducible factor-1α (HIF-1α) signaling pathway was significantly increased following ZnO NPs exposure. Additionally, connective tissue growth factor (CTGF) and plasminogen activator inhibitor-1 (PAI-1), which are directly regulated by HIF-1 and are involved in the pathogenesis of kidney diseases, displayed significantly increased levels following ZnO NPs exposure in HEK-293 cells. HIF-1α knockdown resulted in significantly decreased levels of autophagy and increased cytotoxicity. Therefore, our results suggest that HIF-1α may have a protective role in adaptation to the toxicity of ZnO NPs in kidney cells. In an animal study, fluorescent ZnO NPs were clearly observed in the liver, lungs, kidneys, spleen and heart. ZnO NPs caused histopathological lesions in the kidney and increase in serum creatinine and blood urea nitrogen (BUN) which indicate possible renal possible damage. Moreover, ZnO NPs enhanced the HIF-1α signaling pathway, apoptosis and autophagy in mouse kidney tissues.

Conclusions: ZnO NPs may cause nephrotoxicity, and the results demonstrate the importance of considering the toxicological hazards of ZnO NP production and application, especially for medicinal use.

Electronic supplementary material: The online version of this article (doi:10.1186/s12989-016-0163-3) contains supplementary material, which is available to authorized users.

No MeSH data available.