| Summary: | 碩士 === 國立中央大學 === 生命科學研究所 === 95 === FoxO family contains four members (FoxO1/FKHR, FoxO3/FKHRL1, FoxO4/AFX, FoxO6) that function as transcriptional activators by binding as monomer to the consensus DNA sequence TTGTTTAC. FoxO transcription factors have been implicated in regulating diverse cellular functions including differentiation, metabolism, proliferation, and survival. Recent studies have revealed that PI3K can directly regulate gene expression through phosphorylation. Some studies have shown that FoxO3 can promote atrophy in skeletal muscle. However, their regulation and function in skeletal muscle have not been thoroughly understood. In this study, we have constructed stable clones of FoxO-overexpressed myoblasts by retrovirus transduction. FoxO1-AAA、FoxO6 over-expressed cells lose their ability to differentiate into myotubes, but not the other FoxOs over-expressed stable clones. The gene expression patterns of the later after differentiation were not significantly different from those of control cells. To identify how the differentiation of FoxO1-AAA overexpressed myoblasts were inhibited, we treated them with insulin, Y27632, and A23187, and then observed their influence on terminal myogenic differentiation. Our results revealed that treating the undifferentiated FoxO1-AAA over-expressed cells with insulin would provoke their differentiation. Moreover, we also found the maturity of myotube was changed when treated with different glucose concentrations. Finally we investigated whether well-differentiation of FoxO1-AAA over-expressed cells by insulin treatment was due to effects on glucose metabolism. We also examined the glucose uptake by 2-[1,2-3H(N)]-Deoxy-D-Glucose (2-DG) and the change of cell cycle by flow cytometry.
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