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R. A. Eberwine, E. R. Guerriero, J. Chen, N. Sundarraj; Cell Cycle Progression in Corneal Epithelium, via Rho/ROCK Signaling, Functions via Cytoskeletal Rearrangement. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4292. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Our previously reported study has shown that Rho/ROCK signaling regulates the expression and intracellular distribution of several G1 regulatory proteins and G1/S progression. The present study was to determine whether changes are mediated through actin cytoskeleton assembly/organization.
Rabbit corneal epithelial cells (RCE) in culture were arrested in the G0 phase of the cell cycle by serum deprivation and then allowed to reenter the cell cycle in the presence or absence of 2µm cytochalasin D in serum supplemented medium. The relative levels of specific cyclins and CDKs, their intracellular distribution and the relative levels of mRNAs were determined by western blot analysis, immunocytochemical analysis and real-time RT-PCR, respectively.
When the actin cytoskeleton was disrupted with cytochalasin D 6 hours prior to allowing cells to enter G1 phase, upregulation of cyclins D1 and D3, CDK2, CDK4, CDK6 and their mRNA transcripts were significantly inhibited. Conversely, the protein and mRNA levels of p27Kip1 were upregulated in the cells treated with cytochalasin D during cell cycle progression. These effects of actin filament disruption were very similar to those resulting from Rho/ROCK inhibition during G1 progression.
Microfilament depolymerization results in alterations in the expression of several G1 and G1/S regulatory proteins which were found to be similarly affected by the inhibition of Rho/ROCK signaling pathway. Therefore, Rho/ROCK regulated G1 and G1/S progression is most likely mediated through dynamic changes in actin cytoskeleton.
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