Effects of cofilin phosphorylation on the actin cytoskeleton reorganization induced by shear stress / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To explore the effects of cofilin on the actin cytoskeleton reorganization in osteoblasts induced by fluid shear stress.</p><p><b>METHODS</b>Fluid shear stress (1.2 Pa) was applied to osteoblasts for 0 (control group), 15, 30, 45, 60, 120 min in vitro. Cells were stained with fluorescein isothiocyanate (FITC)-phalloidin for fiber-actin, and confocal laser scanning microscope(CLSM) was used to observe the fluorescence of fiber-actin. Western blotting was used to detect the expression of the cofilin and the phospho-cofilin.</p><p><b>RESULTS</b>Actin filaments became organized into stress fibers that were thicker and more abundant than those in non-flowed cells. The fluorescence intensity (38.00 ± 6.88) of fiber-actin after 120 min (42.93 ± 6.41) loading it was 2.8 times as much as that in control group (15.41 ± 3.60, P < 0.05). Additionally, the level of phospho-cofilin protein was dramatically elevated after loading. Fluid shear stress induced an initial decrease of cofilin at 60 min. However, at 120 min cofilin (0.254 ± 0.026) increased to 1.5 times as much as that at 60 min (0.162 ± 0.004).</p><p><b>CONCLUSIONS</b>The results indicate that cofilin phosphorylation mediates fiber-actin reorganization in the osteoblasts induced by fluid shear stress.</p>

Effect of cytoskeleton integrity on the expression of c-fos in osteoblasts induced by fluid shear stress / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of cytoskeleton integrity on the expression of c-fos gene in osteoblasts induced by fluid shear stress.</p><p><b>METHODS</b>BALB/c mouse primary osteoblasts were divided into four groups (according to fluid shear stress loaded or not and cytochalasin D used or not). The Tagman probe real-time PCR and immunofluorescence were performed to detect the expression levels of c-fos mRNA, c-fos protein and cytoskeleton, respectively. The data were analysed using two-way ANOVA.</p><p><b>RESULTS</b>In control group and cytochalasin D group, fluid shear stress could significantly increase the expression levels of c-fos mRNA (0.1637 +/- 0.0303 and 0.0104 +/- 0.0070, respectively) and protein (177.14 +/- 9.37 and 150.95 +/- 6.17, respectively) in osteoblasts, compared with the unloaded osteoblasts of the control group and the cytochalasin D group (0.0057 +/- 0.0021 and 0.0032 +/- 0.0014, respectively for c-fos mRNA, and 117.96 +/- 4.11 and 119.77 +/- 5.19, respectively for protein, P < 0.05). Induced by the fluid shear stress, the expression levels of c-fos mRNA and protein in cytochalasin D group were lower than control group, and the difference had statistical significance (P < 0.05).</p><p><b>CONCLUSIONS</b>The cytoskeleton integrity in osteoblasts was essential to the expression of c-fos gene induced by fluid shear stress.</p>