Downregulation of aquaporin 5 induced by vector-based short hairpin RNA and its effect on MUC5AC gene expression in human airway submucosal gland cells.
ABSTRACT The aquaporins (AQPs) are a family of homologous water channels expressed in many epithelial and endothelial cells, however no reliable and non-toxic inhibitors of AQPs have been reported yet. Our researchers have analyzed the changes of AQP5 expression induced by vector-based short hairpin RNA (shRNA) in the human airway submucosal gland cell line (SPC-A1) and observed its regulation on the expression of MUC5AC gene. Localizations of AQP5 and MUC5AC in SPC-A1cells were detected by Immunofluorescence. AQP5 mRNA was significantly reduced by 75.1% one day after transfection with specific shRNA, named shAQP5. However, the significant suppression of AQP5 protein did not appear until day 5 after transfection. MUC5AC mRNA was remarkably increased by 119.9% On day 3 after shAQP5 transfection, while comparable MUC5AC protein changes were not found in SPC-A1 cells with flow cytometry analysis. These results indicate that vector-based shRNA could be used as a potential tool to inhibit the expression of AQP5. This is the first investigation providing evidence demonstrating the regulation of the mucin gene by AQP5 gene silencing.
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ABSTRACT: Aquaporin 5 (AQP5) is widely expressed in various organ and tissues. In light of the novel oncogenic properties of aquaporins (AQPs), here we investigated the effect of AQP5 knockdown by RNAi on transmembrane osmotic water permeability, cell migration potential and cell volume regulation ability. AQP5 expression was inhibited by short hairpin RNA in SPC-A1 cells, a lung adenocarcinoma cell line. Cells loaded with a fluoroprobe (calcein-AM) were immersed in either isosmotic, hyperosmotic or hyposmotic solutions, and fluorescence intensity was recorded using confocal microscopy. These measurements were used to calculate osmotic water permeability coefficients (Pf) and to monitor regulated volume decrease (RVD). Tumor cell migration and invasion assays were performed in a modified Boyden chamber. Wound healing and colony forming ability were also tested. Although self-quenching was not found in SPC-A1 cells, we observed a linear relationship between fluorescence intensity and cell water volume, suggesting that this method is a sensitive and reproducible way to measure single-cell transmembrane water permeability. Cells in which the AQP5 gene was silenced showed a 49.4% decrease in osmotic water permeability, a 55.3% decrease in migration and a 28.4% decrease in invasion potential. In addition, RVD decreased remarkably with reduced osmotic water permeability. Our results suggest that AQP5, which mediates water permeability and thus regulates cell shape and volume, is a potentially important determinant in cell migration.Respiratory Physiology & Neurobiology 02/2011; 176(3):110-7. · 1.97 Impact Factor
- Academic Journal of Second Military Medical University 01/2008; 28(2):126-130.
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ABSTRACT: Background and objective: The aim of this study was to investigate the changes in expression of aquaporins (AQP) during differentiation of human bronchial epithelial cells and the role of lipopolysaccharide (LPS) in AQP expression. Methods: The levels of AQP3, AQP4 and AQP5 transcripts in human primary cultured bronchial epithelial cells were evaluated by real-time polymerase chain reaction at different time points before and after treatment with LPS. Western blotting was performed to assess the effects of LPS on AQP3, AQP4 and AQP5 expressions in normal human bronchial epithelial cells. Using pharmacological tools, the pathways involved in the regulation of LPS-induced changes in AQP5 were further explored. Results: The levels of AQP3, AQP4 and AQP5 transcripts were increased during differentiation of human bronchial epithelial cells. Expression of AQP5, but not AQP3 or AQP4, was downregulated by LPS. LPS-induced downregulation of AQP5 was inhibited by p38 and c-Jun N-terminal kinase (JNK) inhibitors. Conclusions: This study demonstrated that LPS decreases AQP5, but not AQP3 or AQP4, expression in human primary bronchial epithelial cells. The downregulation of AQP5 expression is mediated through a p38/JNK signalling pathway.Respirology 07/2012; 17(7):1144-9. · 3.50 Impact Factor