Role and mechanism of focal adhesion kinase in inducing osteogenic differentiation of mouse embryonic fibroblasts cells / 中国组织工程研究

ABSTRACT

BACKGROUND: Focal adhesion kinase (FAK) is regarded as a bridge molecule of “biomaterial/scaffold,” “seed cell,” and “growth factor” in bone tissue engineering. Exploration on the role and mechanism of focal adhesion kinase in inducing osteogenic differentiation of related seed cells is particularly important for the development and application of bone tissue engineering. OBJECTIVE: To determine the role and mechanism of FAK in inducing osteogenic differentiation of immortalized mouse embryonic fibroblasts (iMEF). METHODS: Under the same induction conditions, the iMEF cells with (iMEFFAK+/+ cells) or without FAK knockout (iMEFFAK-/- cells), treated with or without PI3K/ AKT phosphorylation inhibitor LY294002 or ERK1/2 phosphorylation inhibitor U0126, were induced to differentiate into osteoblasts. The morphological changes of iMEFs (iMEFFAK+/+ and iMEFFAK-/-) at different induction periods were observed under a microscope. Runx2 protein levels and corresponding p-ERK1/2 and p-AKT levels were detected by western blot. RT-PCR technology was used to detect the transcription level of Runx2 gene. Finally, the induced iMEFs (iMEFFAK+/+ and iMEFFAK-/-) were stained with alizarin red staining for calcium nodules 3 weeks after osteogenesis induction. RESULTS AND CONCLUSION: The osteogenic effect of iMEFFAK-/- cells was lower than that of iMEFFAK+/+ cells under the same induction conditions. Both the expression levels of Runx2 and the osteogenic effect of iMEFFAK+/+ cells and iMEFFAK-/- cells treated with LY294002 decreased significantly compared with the control group. Both the expression levels of Runx2 and the osteogenic effect of iMEFFAK+/+ cells and iMEFFAK-/- cells treated with U0126 decreased significantly compared with the control group. To conclude, silencing FAK expression can inhibit osteogenic differentiation of mouse embryonic fibroblasts by reducing the levels of PI3K/AKT, serine/threonine protein kinase, and ERK1/2 phosphorylation levels.