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Bit1—a potential positive regulator of epithelial–mesenchymal transition in lens epithelial cells

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Abstract

Purpose

Posterior capsule opacification (PCO) is a common postoperative complication of cataract surgery. Epithelial–mesenchymal transition (EMT) of lens epithelial cells (LECs) is an important initial step of PCO pathogenesis. We have previously shown that Bit1 expresses in rat LECs. In this study, we aim to investigate the role of Bit1 in the EMT of human LECs.

Methods

The expression of Bit1 was firstly detected in human PCO-attached LECs and human lens cell line SRA01/04 by real-time PCR and immunofluorescence staining. The proliferation and migration of Bit1 knockdown SRA01/04 cells were evaluated by cell counting, wound-healing assay, and transwell migration assay. The EMT of LECs was triggered by TGF-β2, and then the effect of Bit1 on EMT with a key biomarker of α-smooth muscle actin (α-SMA) was analyzed by siRNA knockdown assay, and the reversal of EMT was validated by real-time PCR and western blot.

Results

Bit1 was obviously augmented in LECs derived from PCO tissues and Bit1 expressed with high levels in the cytoplasm of cultured SRA01/04 cells. Cell proliferation, invasion, and migration, as well as α-SMA expression, were significantly decreased in Bit1 knockdown SRA01/04 cells. While TGF-β2 elevated Bit1 and α-SMA expression levels in a dose-dependent manner, with peak levels at 10 ng/ml of TGF-β2 treatment, suppression of Bit1 in SRA01/04 cells reversed the EMT process. TGF-β2 induced elevation of α-SMA expression level, as well as migration, and invasion abilities were all suppressed by Bit1 deficiency.

Conclusions

These findings reveal that Bit1 promotes TGF-β2 induced α-SMA expression and acts as an positive regulator of EMT. Suppressing Bit1 inhibits the proliferation, migration, and EMT of LECs. Bit1 may be a potential novel therapeutic target for the prevention and treatment of PCO.

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Authors’ contributions

Research design: BM, ML. Performed the experiments: XHW, JR and BM. Analyzed the data: XHW and BM. Wrote the manuscript: BM. Obtained the funding: BM.

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Authors and Affiliations

  1. Department of Ophthalmology, Shanghai Ninth People’s Hospital affiliated Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, China

    Xinhua Wu, Jing Ruan, Bo Ma & Min Luo

Authors
  1. Xinhua Wu
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  2. Jing Ruan
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  3. Bo Ma
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  4. Min Luo
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Corresponding author

Correspondence to Bo Ma.

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Funding

This study was supported by the National Natural Science Foundation of China (Grant No. 81300773). The sponsor had no role in the design or conduct of this research.

Conflict of interest

All authors certify that they have no non-financial interest in the subject matter or materials discussed in this manuscript.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the Ethics Committee of Shanghai Ninth People’s Hospital affiliated Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China, and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

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Informed consent was obtained from all individual participants included in the study.

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Wu, X., Ruan, J., Ma, B. et al. Bit1—a potential positive regulator of epithelial–mesenchymal transition in lens epithelial cells. Graefes Arch Clin Exp Ophthalmol 254, 1311–1318 (2016). https://doi.org/10.1007/s00417-016-3357-3

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  • DOI: https://doi.org/10.1007/s00417-016-3357-3

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