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Endothelial to mesenchymal transition contributes to arsenic-trioxide-induced cardiac fibrosis

View Article: PubMed Central - PubMed

ABSTRACT

Emerging evidence has suggested the critical role of endothelial to mesenchymal transition (EndMT) in fibrotic diseases. The present study was designed to examine whether EndMT is involved in arsenic trioxide (As2O3)-induced cardiac fibrosis and to explore the underlying mechanisms. Cardiac dysfunction was observed in rats after exposure to As2O3 for 15 days using echocardiography, and the deposition of collagen was detected by Masson’s trichrome staining and electron microscope. EndMT was indicated by the loss of endothelial cell markers (VE-cadherin and CD31) and the acquisition of mesenchymal cell markers (α-SMA and FSP1) determined by RT-PCR at the mRNA level and Western blot and immunofluorescence analysis at the protein level. In the in-vitro experiments, endothelial cells acquired a spindle-shaped morphology accompanying downregulation of the endothelial cell markers and upregulation of the mesenchymal cell markers when exposed to As2O3. As2O3 activated the AKT/GSK-3β/Snail signaling pathway, and blocking this pathway with PI3K inhibitor (LY294002) abolished EndMT in As2O3-treated endothelial cells. Our results highlight that As2O3 is an EndMT-promoting factor during cardiac fibrosis, suggesting that targeting EndMT is beneficial for preventing As2O3-induced cardiac toxicity.

No MeSH data available.


Related in: MedlinePlus

As2O3 activates the AKT/GSK-3β/Snail pathway.(a) HAECs were treated with or without As2O3, and the expression of Snail and the activation of AKT and GSK-3β were determined by western blotting. (b) Relative mRNA expression level of AKT, GSK-3β and Snail in different groups. **p < 0.01 vs. untreated condition (0 μmol/l As2O3). Data are expressed as mean ± SEM, n = 3–5.
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f5: As2O3 activates the AKT/GSK-3β/Snail pathway.(a) HAECs were treated with or without As2O3, and the expression of Snail and the activation of AKT and GSK-3β were determined by western blotting. (b) Relative mRNA expression level of AKT, GSK-3β and Snail in different groups. **p < 0.01 vs. untreated condition (0 μmol/l As2O3). Data are expressed as mean ± SEM, n = 3–5.

Mentions: Multiple signaling pathways are involved in the process of EndMT, such as the TGF-β pathway, Notch pathway, and PI3K/AKT pathway26272829. The AKT/GSK-3β/Snail pathway has been proposed to play an important role in inducing EMT3031. Because EndMT is a special form of EMT, here we hypothesized that As2O3 may induce EndMT via the AKT/GSK-3β/Snail pathway. As expected, upon treatment with a high concentration of As2O3 (8 μmol/l) for 24 h, phosphorylation of AKT and GSK-3β was dramatically increased and Snail expression was significantly enhanced in HAECs. The total protein and mRNA levels of AKT and GSK-3β were unaffected by As2O3 at concentrations of 2, 4 and 8 μmol/l (Fig. 5a,b). To further demonstrate the phenomenon of AKT/GSK-3β/Snail signaling activation in vivo, we double-stained CD31/p-AKT, CD31/p-GSK-3β and CD31/Snail in heart tissues. The results in Supplementary Figure 3 showed that the expression of p-AKT, p-GSK-3β and Snail were at a higher level in endothelial cells of myocardial sections from As2O3-treated rats, which suggested that the AKT/GSK-3β/Snail signaling pathway is also activated in vivo.


Endothelial to mesenchymal transition contributes to arsenic-trioxide-induced cardiac fibrosis
As2O3 activates the AKT/GSK-3β/Snail pathway.(a) HAECs were treated with or without As2O3, and the expression of Snail and the activation of AKT and GSK-3β were determined by western blotting. (b) Relative mRNA expression level of AKT, GSK-3β and Snail in different groups. **p < 0.01 vs. untreated condition (0 μmol/l As2O3). Data are expressed as mean ± SEM, n = 3–5.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037371&req=5

f5: As2O3 activates the AKT/GSK-3β/Snail pathway.(a) HAECs were treated with or without As2O3, and the expression of Snail and the activation of AKT and GSK-3β were determined by western blotting. (b) Relative mRNA expression level of AKT, GSK-3β and Snail in different groups. **p < 0.01 vs. untreated condition (0 μmol/l As2O3). Data are expressed as mean ± SEM, n = 3–5.
Mentions: Multiple signaling pathways are involved in the process of EndMT, such as the TGF-β pathway, Notch pathway, and PI3K/AKT pathway26272829. The AKT/GSK-3β/Snail pathway has been proposed to play an important role in inducing EMT3031. Because EndMT is a special form of EMT, here we hypothesized that As2O3 may induce EndMT via the AKT/GSK-3β/Snail pathway. As expected, upon treatment with a high concentration of As2O3 (8 μmol/l) for 24 h, phosphorylation of AKT and GSK-3β was dramatically increased and Snail expression was significantly enhanced in HAECs. The total protein and mRNA levels of AKT and GSK-3β were unaffected by As2O3 at concentrations of 2, 4 and 8 μmol/l (Fig. 5a,b). To further demonstrate the phenomenon of AKT/GSK-3β/Snail signaling activation in vivo, we double-stained CD31/p-AKT, CD31/p-GSK-3β and CD31/Snail in heart tissues. The results in Supplementary Figure 3 showed that the expression of p-AKT, p-GSK-3β and Snail were at a higher level in endothelial cells of myocardial sections from As2O3-treated rats, which suggested that the AKT/GSK-3β/Snail signaling pathway is also activated in vivo.

View Article: PubMed Central - PubMed

ABSTRACT

Emerging evidence has suggested the critical role of endothelial to mesenchymal transition (EndMT) in fibrotic diseases. The present study was designed to examine whether EndMT is involved in arsenic trioxide (As2O3)-induced cardiac fibrosis and to explore the underlying mechanisms. Cardiac dysfunction was observed in rats after exposure to As2O3 for 15&thinsp;days using echocardiography, and the deposition of collagen was detected by Masson&rsquo;s trichrome staining and electron microscope. EndMT was indicated by the loss of endothelial cell markers (VE-cadherin and CD31) and the acquisition of mesenchymal cell markers (&alpha;-SMA and FSP1) determined by RT-PCR at the mRNA level and Western blot and immunofluorescence analysis at the protein level. In the in-vitro experiments, endothelial cells acquired a spindle-shaped morphology accompanying downregulation of the endothelial cell markers and upregulation of the mesenchymal cell markers when exposed to As2O3. As2O3 activated the AKT/GSK-3&beta;/Snail signaling pathway, and blocking this pathway with PI3K inhibitor (LY294002) abolished EndMT in As2O3-treated endothelial cells. Our results highlight that As2O3 is an EndMT-promoting factor during cardiac fibrosis, suggesting that targeting EndMT is beneficial for preventing As2O3-induced cardiac toxicity.

No MeSH data available.


Related in: MedlinePlus