Cell Density-Dependent Fibroblast Growth Factor-2 Signaling Regulates Syndecan-4 Expression in Cultured Vascular Endothelial Cells

Syndecan-4 is a member of the syndecan family of transmembrane heparan sulfate proteoglycans, and is involved in cell protection, proliferation, and the blood coagulation-fibrinolytic system in vascular endothelial cells. Heparan sulfate chains enable fibroblast growth factor-2 (FGF-2) to form a complex with its receptor and to transduce the cell growth signal. In the present study, bovine aortic endothelial cells were cultured, and the intracellular signal pathways that mediate the regulation of syndecan-4 expression in dense and sparse cultures by FGF-2 were analyzed. We demonstrated the cell density-dependent differential regulation of syndecan-4 expression. Specifically, we found that FGF-2 upregulated the synthesis of syndecan-4 in vascular endothelial cells via the MEK1/2-ERK1/2 pathway in dense cell cultures, with only a transcriptional induction of syndecan-4 at a low cell density via the Akt pathway. This study highlights a critical mechanism underlying the regulation of endothelial cell functions by proteoglycans

グラニュラー物質の高圧下での量子輸送特性の変化

Co-Al-0グラニュラー薄膜は、Co粒子がAl酸化物絶縁相にナノスケールで分散した構造をもつ金属-非金属グラニュラー物質でトンネル型磁気抵抗効果(Tunnel Magnetoresistance:TMR)を示す典型的物質である。今回我々は低温・高圧下でこの物質の電気抵抗の測定を行い、その特徴ある温度依存性の圧力変化及びTMRの加圧による増大を測定した。これらの結果について概観し、その背後に横たわる物理的な機構を考察する。Co-Al-O granuler films consist of nanometer-sized Co granules embedded in an Al-oxide matrix, which are typical examples exhibiting tunnel magnetroresistance(TMR). We have measured the electrical resistance of this granular film under high pressure and magnetic field. It is found that the temperature dependence of resistivity is affected strongly and TMR is enhanced by applying pressure. We suggested that the higher order tunneling model is able to explain the experimental results