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Objective The study is to investigate the role of miR-328 in endothelial mesenchymal transition (EMT)induced by high glucose in human umbilical vein endothelial cells (HUVECs)and its signaling mechanism.Methods HUVECs were cultured in high glucose environment to induce EMT;The recombinant lentiviruses were created by miR-328 and antagomiR- 328 transfection of HUVECs.The experiment was divided into seven groups: normal glucose;mannitol group;high glucose;miR-328;miR-328 virus negative control;high glucose + U0126;miR-328 + U0126.Double immunofluorescent staining was used to determine expression of EMT markers;Changes in miR-328 expression is examined by RT-qPCR;The expressions of type Ⅰ/Ⅲ collagen,p-MEK1/2 and p-ERK1/2 are examined by Western blot.Results 1)HUVECs showed positive staining for CD31 and α-SMA in high glucose group.2)The expression of miR-328 was up-regulated(P<0.05)in HUVECs treated by high glucose or miR-328.Compared with high glucose group or miR-328 group,miR-328 expression was less pronounced aftertreatment with U0126.3)The expressions of type Ⅰ/Ⅲ collagen increased in HUVECs treated by high glucose or miR-328(P<0.05) Compared with high glucose group or miR-328 group,typeⅠ/Ⅲ collagen expressions were less pronounced after treatment with U0126.4)The expressions of p-MEK1/2 and p-ERK1/2 were increased in HUVECs treated by high glucose or miR-328 in comparison to the control group (P<0.05);a lower expression of p-MEK1/2 and p-ERK1/2 were observed in U0126 group than in high glucose group or miR-328 group.Conclusions The phenomenon of EMT in HUVECs is induced by high glucose with increased expression of miR-328;overexpression of miR-328 induced EMT in HUVECs;miR-328 induced EMT is related with MEK1/2-ERK1/2 signaling pathway.
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The mitogenic effects of periodic mechanical stress on chondrocytes have been studied extensively but the mechanisms whereby chondrocytes sense and respond to periodic mechanical stress remain a matter of debate. We explored the signal transduction pathways of chondrocyte proliferation and matrix synthesis under periodic mechanical stress. In particular, we sought to identify the role of the MEK1/2-ERK1/2 signaling pathway in chondrocyte proliferation and matrix synthesis following cyclic physiologic mechanical compression. Under periodic mechanical stress, both rat chondrocyte proliferation and matrix synthesis were significantly increased (P < 0.05) and were associated with increases in the phosphorylation of Src, PLCγ1, MEK1/2, and ERK1/2 (P < 0.05). Pretreatment with the MEK1/2-ERK1/2 selective inhibitor, PD98059, and shRNA targeted to ERK1/2 reduced periodic mechanical stress-induced chondrocyte proliferation and matrix synthesis (P < 0.05), while the phosphorylation levels of Src-Tyr418 and PLCγ1-Tyr783 were not inhibited. Proliferation, matrix synthesis and phosphorylation of MEK1/2-Ser217/221 and ERK1/2-Thr202/Tyr204 were inhibited after pretreatment with the PLCγ1 inhibitor U73122 in chondrocytes in response to periodic mechanical stress (P < 0.05), while the phosphorylation site of Src-Tyr418 was not affected. Inhibition of Src activity with PP2 and shRNA targeted to Src abrogated chondrocyte proliferation and matrix synthesis (P < 0.05) and attenuated PLCγ1, MEK1/2 and ERK1/2 activation in chondrocytes subjected to periodic mechanical stress (P < 0.05). These findings suggest that periodic mechanical stress promotes chondrocyte proliferation and matrix synthesis in part through the Src-PLCγ1-MEK1/2-ERK1/2 signaling pathway, which links these three important signaling molecules into a mitogenic cascade.