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Zinc supplementation protects against cadmium accumulation and cytotoxicity in Madin-Darby bovine kidney cells.

Zhang D, Liu J, Gao J, Shahzad M, Han Z, Wang Z, Li J, Sjölinder H - PLoS ONE (2014)

Bottom Line: Metallothioneins (MTs) are metal-binding proteins that play an essential role in heavy metal ion detoxification.We found that co-exposure to Zn2+ and Cd2+ synergistically enhanced RNA and protein expression of MT-1, MT-2, and the metal-regulatory transcription factor 1 in MDBK cells.Notably, addition of Zn2+ reduced the amounts of cytosolic Cd2+ detected following MDBK exposure to 10 μM Cd2+.

View Article: PubMed Central - PubMed

Affiliation: College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, PR China.

ABSTRACT
Cadmium ions (Cd2+) have been reported to accumulate in bovine tissues, although Cd2+ cytotoxicity has not been investigated thoroughly in this species. Zinc ions (Zn2+) have been shown to antagonize the toxic effects of heavy metals such as Cd2+ in some systems. The present study investigated Cd2+ cytotoxicity in Madin-Darby bovine kidney (MDBK) epithelial cells, and explored whether this was modified by Zn2+. Exposure to Cd2+ led to a dose- and time-dependent increase in apoptotic cell death, with increased intracellular levels of reactive oxygen species and mitochondrial damage. Zn2+ supplementation alleviated Cd2+-induced cytotoxicity and this protective effect was more obvious when cells were exposed to a lower concentration of Cd2+ (10 μM), as compared to 50 μM Cd2+. This indicated that high levels of Cd2+ accumulation might induce irreversible damage in bovine kidney cells. Metallothioneins (MTs) are metal-binding proteins that play an essential role in heavy metal ion detoxification. We found that co-exposure to Zn2+ and Cd2+ synergistically enhanced RNA and protein expression of MT-1, MT-2, and the metal-regulatory transcription factor 1 in MDBK cells. Notably, addition of Zn2+ reduced the amounts of cytosolic Cd2+ detected following MDBK exposure to 10 μM Cd2+. These findings revealed a protective role of Zn2+ in counteracting Cd2+ uptake and toxicity in MDBK cells, indicating that this approach may provide a means to protect livestock from excessive Cd2+ accumulation.

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Effect of Zn2+ on Cd2+-triggered mitochondrial depolarization.(A) MDBK cells were treated with Cd2+ alone (0, 10, 50 μM), or in combination with Zn2+ (0, 10, 50 μM), for 6 h. Mitochondrial membrane polarization (MMP) was determined by staining with JC-1 probe and imaging using a fluorescence microscope at ×200 magnification. (B) MDBK cells were treated as described above for the indicated time periods. The percentage of green fluorescent cells (indicating reduced MMP) was quantified by flow cytometry. Values shown are the mean ± SD (n = 4). #P<0.05, ##P<0.01, and ###P<0.001 compared to the medium-treated control group; *P<0.05 and **P<0.01 compared to the cells exposed to Cd2+ alone (10 or 50 μM).
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pone-0103427-g003: Effect of Zn2+ on Cd2+-triggered mitochondrial depolarization.(A) MDBK cells were treated with Cd2+ alone (0, 10, 50 μM), or in combination with Zn2+ (0, 10, 50 μM), for 6 h. Mitochondrial membrane polarization (MMP) was determined by staining with JC-1 probe and imaging using a fluorescence microscope at ×200 magnification. (B) MDBK cells were treated as described above for the indicated time periods. The percentage of green fluorescent cells (indicating reduced MMP) was quantified by flow cytometry. Values shown are the mean ± SD (n = 4). #P<0.05, ##P<0.01, and ###P<0.001 compared to the medium-treated control group; *P<0.05 and **P<0.01 compared to the cells exposed to Cd2+ alone (10 or 50 μM).

Mentions: Mitochondria are both the source and the target of ROS [21], and we therefore explored the impact of Cd2+ exposure on mitochondrial MMP. MDBK cells were exposed to Cd2+ and/or Zn2+ for 6 h prior to MMP evaluation by JC-1 fluorescence imaging of (Fig. 3A). Exposure to 10 μM or 50 μM Cd2+ caused green JC-1 fluorescence in MDBK cells, indicating that the MMP was reduced and that the mitochondria were therefore depolarized. Addition of Zn2+ reversed this Cd2+-induced decline in MMP, with the best effect observed in the presence of 50 μM of Zn2+. Treatment with 10 μM or 50 μM Zn2+ alone did not obviously alter MMP in MDBK cells.


Zinc supplementation protects against cadmium accumulation and cytotoxicity in Madin-Darby bovine kidney cells.

Zhang D, Liu J, Gao J, Shahzad M, Han Z, Wang Z, Li J, Sjölinder H - PLoS ONE (2014)

Effect of Zn2+ on Cd2+-triggered mitochondrial depolarization.(A) MDBK cells were treated with Cd2+ alone (0, 10, 50 μM), or in combination with Zn2+ (0, 10, 50 μM), for 6 h. Mitochondrial membrane polarization (MMP) was determined by staining with JC-1 probe and imaging using a fluorescence microscope at ×200 magnification. (B) MDBK cells were treated as described above for the indicated time periods. The percentage of green fluorescent cells (indicating reduced MMP) was quantified by flow cytometry. Values shown are the mean ± SD (n = 4). #P<0.05, ##P<0.01, and ###P<0.001 compared to the medium-treated control group; *P<0.05 and **P<0.01 compared to the cells exposed to Cd2+ alone (10 or 50 μM).
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4126686&req=5

pone-0103427-g003: Effect of Zn2+ on Cd2+-triggered mitochondrial depolarization.(A) MDBK cells were treated with Cd2+ alone (0, 10, 50 μM), or in combination with Zn2+ (0, 10, 50 μM), for 6 h. Mitochondrial membrane polarization (MMP) was determined by staining with JC-1 probe and imaging using a fluorescence microscope at ×200 magnification. (B) MDBK cells were treated as described above for the indicated time periods. The percentage of green fluorescent cells (indicating reduced MMP) was quantified by flow cytometry. Values shown are the mean ± SD (n = 4). #P<0.05, ##P<0.01, and ###P<0.001 compared to the medium-treated control group; *P<0.05 and **P<0.01 compared to the cells exposed to Cd2+ alone (10 or 50 μM).
Mentions: Mitochondria are both the source and the target of ROS [21], and we therefore explored the impact of Cd2+ exposure on mitochondrial MMP. MDBK cells were exposed to Cd2+ and/or Zn2+ for 6 h prior to MMP evaluation by JC-1 fluorescence imaging of (Fig. 3A). Exposure to 10 μM or 50 μM Cd2+ caused green JC-1 fluorescence in MDBK cells, indicating that the MMP was reduced and that the mitochondria were therefore depolarized. Addition of Zn2+ reversed this Cd2+-induced decline in MMP, with the best effect observed in the presence of 50 μM of Zn2+. Treatment with 10 μM or 50 μM Zn2+ alone did not obviously alter MMP in MDBK cells.

Bottom Line: Metallothioneins (MTs) are metal-binding proteins that play an essential role in heavy metal ion detoxification.We found that co-exposure to Zn2+ and Cd2+ synergistically enhanced RNA and protein expression of MT-1, MT-2, and the metal-regulatory transcription factor 1 in MDBK cells.Notably, addition of Zn2+ reduced the amounts of cytosolic Cd2+ detected following MDBK exposure to 10 μM Cd2+.

View Article: PubMed Central - PubMed

Affiliation: College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, PR China.

ABSTRACT
Cadmium ions (Cd2+) have been reported to accumulate in bovine tissues, although Cd2+ cytotoxicity has not been investigated thoroughly in this species. Zinc ions (Zn2+) have been shown to antagonize the toxic effects of heavy metals such as Cd2+ in some systems. The present study investigated Cd2+ cytotoxicity in Madin-Darby bovine kidney (MDBK) epithelial cells, and explored whether this was modified by Zn2+. Exposure to Cd2+ led to a dose- and time-dependent increase in apoptotic cell death, with increased intracellular levels of reactive oxygen species and mitochondrial damage. Zn2+ supplementation alleviated Cd2+-induced cytotoxicity and this protective effect was more obvious when cells were exposed to a lower concentration of Cd2+ (10 μM), as compared to 50 μM Cd2+. This indicated that high levels of Cd2+ accumulation might induce irreversible damage in bovine kidney cells. Metallothioneins (MTs) are metal-binding proteins that play an essential role in heavy metal ion detoxification. We found that co-exposure to Zn2+ and Cd2+ synergistically enhanced RNA and protein expression of MT-1, MT-2, and the metal-regulatory transcription factor 1 in MDBK cells. Notably, addition of Zn2+ reduced the amounts of cytosolic Cd2+ detected following MDBK exposure to 10 μM Cd2+. These findings revealed a protective role of Zn2+ in counteracting Cd2+ uptake and toxicity in MDBK cells, indicating that this approach may provide a means to protect livestock from excessive Cd2+ accumulation.

Show MeSH
Related in: MedlinePlus