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Britta Dreier, Vijaykrishna Raghunathan, Paul Russell, Christopher J. Murphy; Involvement Of Yap And TAZ In The Response Of Corneal Cells To Biophysical Cues. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4202.
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To determine the modulation of mechanosensors YAP (Yes-associated protein) and TAZ (transcriptional coactivator with PDZ-binding motif), and associated signaling molecules, by biophysical cues in corneal cells.
Immortalized human corneal epithelial cells and primary human stromal fibroblasts were utilized for our studies. To analyze the effect of topographic cues, anisotropically patterned NOA81 surfaces with pitches (pitch = ridge + groove width) of 400, 1400, and 4000 nm as well as chemically identical planar surfaces were fabricated. To investigate the impact of substrate rigidity, polyacrylamide gels with elastic modulus of 25 kPa, 50 kPa and 75 kPa were used. Tissue culture plastic polystyrene (TCP), which possesses modulus in GPa range, served as a control. Cells were cultured on the different surfaces overnight and total RNA was isolated. Quantitative PCR was performed to examine mRNA levels of genes involved in the YAP pathway including YAP, TAZ, 14-3-3 sigma (SFN) and Transforming Growth Factor beta-2 (TGFb2).
A differential and cell dependent response to the biophysical cues of both substrate rigidity and topography was observed. Corneal epithelial cells were most responsive to the biologically relevant scale of topography (400 nm pitch) with upregulation in YAP, SFN, and TGFb2 but no change of TAZ expression in epithelial cells exposed to topographic cues. In fibroblasts, YAP and SFN expression remained unaltered on all topographically patterned surfaces while the expression of TGFb2 was upregulated on all patterned surfaces and TAZ was downregulated on the 400 nm pitch. In epithelial cells, expression levels of YAP, TAZ and SFN were significantly increased on 25 and 75 kPa gels. In fibroblasts on 25 kPa gels, SFN expression was significantly downregulated and TGFb2 was upregulated compared with cells cultured on TCP while the expression of YAP was unaltered in fibroblasts on gels or TCP. Expression of TAZ was increased in stromal cells grown on 75 kPa gels.
Our data shows that the biophysical attributes of the corneal microenvironment cause changes in the expression of several cell signaling molecules that are corneal cell type dependent and strongly suggests a fundamental involvement of YAP, TAZ, SFN and TGFb2 in the response of corneal cells to their biophysical microenvironment.
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