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Y. Zhu, S.-Y. Chen, S. C. Tseng; Transit Knockdown of p120, but Not β-Catenin, N-Cadherin and ZO-1, Promotes Proliferation of Post-Confluent ARPE-19 Cells. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1669.
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© ARVO (1962-2015); The Authors (2016-present)
p120, β-catenin, N-cadherin and ZO-1 are major cell junction molecules controlling the cell junction formation in many types of cells. However, it remains unclear which one(s) of those proteins contribute to the mitotic block caused by confluency in ARPE-19, a human retinal pigment epithelium (RPE) cell line with normal karyology.
Post-confluent ARPE-19 cells were treated with 100 nM p120 catenin, β-catenin, N-cadherin or ZO-1 siRNA for 2 days, and compared to their respective controls similarly treated with scrambled RNA or PBS. Before termination, cells were labeled with 10 µM BrdU for 24h. Real-time PCR and Western blotting for p120 catenin, β-catenin, N-cadherin and ZO-1 transcripts and proteins were performed. Double immunostaining to p120 catenin, β-catenin, N-cadherin or ZO-1 and BrdU were compared.
p120 catenin, β-catenin, N-cadherin or ZO-1 siRNA dramatically downregulated their corresponding mRNA and immunoreactive protein expression from the intercellular junction in post-confluent ARPE-19 cells. As compared to the controls treated with scRNA and PBS, p120 catenin siRNA treatment resulted in a significant increase of BrdU-labeled nuclei colocalized with p120 catenin that was translocated from the intercellular junction. In contrast, β-catenin, N-cadherin or ZO-1 siRNA treatment did not resulted in any significant increase of BrdU labeling. Western blot analysis confirmed that p120 catenin siRNA knockdown significantly reduced the protein expression of p120-catenin and ZO-1, but not that of N-cadherin and β-catenin.
These results collectively indicate that transit knockdown of p120 catenin, but not other junction molecules, unlocks the mitotic block of post-confluent ARPE-19 cells.
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