Hsieh H J, Li N Q, Frangos J A
Department of Chemical Engineering, Pennsylvania State University, University Park 16802.
J Cell Physiol. 1993 Jan;154(1):143-51. doi: 10.1002/jcp.1041540118.
The effects of pulsatile and steady fluid flow on the mRNA levels of proto-oncogenes c-fos, c-jun, and c-myc in cultured human umbilical vein endothelial cells (HUVEC) were investigated. c-fos mRNA levels in stationary cultures were very low. A 1 Hz pulsatile flow with an average shear stress of 16 dynes/cm2 induced a dramatic increase of c-fos mRNA levels in HUVEC 0.5 h after the onset of flow, which declined rapidly to basal levels within 1 h. Steady flow with a similar shear stress also induced a transient increase of c-fos mRNA levels, but to a lesser extent. In addition, increased c-fos mRNA levels were observed when low shear (2-6 dynes/cm2) was replaced by high shear (16-33 dynes/cm2). Pulsatile and steady flow caused a slight increase of c-jun and c-myc mRNA levels. The role of pulsatility was also investigated in platelet-derived growth factor (PDGF) expression. Pulsatile flow induced a transient increase of PDGF A- and B-chain mRNA levels with peaks at 1.5-2 h. Pulsatile flow, which was more stimulatory in mediating c-fos expression, however, was less stimulatory than steady flow in mediating PDGF expression. By using various inhibitors, protein kinase C was found to be an important mediator in flow-induced c-fos expression, with the involvement of G proteins, phospholipase C, and intracellular calcium. Protein kinase C was previously shown as a possible major mediator in flow-induced PDGF expression which, at least partly, appeared to follow the induction mechanism of c-fos, suggesting a possible connection between c-fos and PDGF induction. However, the c-fos antisense treatment, which significantly inhibited c-fos transcription, failed to block the flow-induced PDGF expression, suggesting that flow-induced c-fos expression may not play an important role in the mechanism of flow-induced PDGF expression. The difference in the induction of c-fos and PDGF expression under pulsatile as compared to steady flow indicates that a complex, flow-mediated regulatory mechanism of gene expression exists in HUVEC. The increased expression of these proto-oncogenes mediated by flow may be important in regulating long-term cellular responses.
研究了搏动性和稳定性流体流动对培养的人脐静脉内皮细胞（HUVEC）中原癌基因c-fos、c-jun和c-myc的mRNA水平的影响。静止培养物中c-fos mRNA水平非常低。平均剪切应力为16达因/平方厘米的1赫兹搏动性流动在流动开始后0.5小时诱导HUVEC中c-fos mRNA水平急剧增加，1小时内迅速降至基础水平。具有相似剪切应力的稳定性流动也诱导c-fos mRNA水平短暂增加，但程度较小。此外，当低剪切力（2 - 6达因/平方厘米）被高剪切力（16 - 33达因/平方厘米）取代时，观察到c-fos mRNA水平增加。搏动性和稳定性流动导致c-jun和c-myc mRNA水平略有增加。还研究了搏动性在血小板衍生生长因子（PDGF）表达中的作用。搏动性流动诱导PDGF A链和B链mRNA水平短暂增加，峰值出现在1.5 - 2小时。然而，在介导c-fos表达方面更具刺激性的搏动性流动，在介导PDGF表达方面比稳定性流动刺激性小。通过使用各种抑制剂，发现蛋白激酶C是流动诱导的c-fos表达中的重要介质，涉及G蛋白、磷脂酶C和细胞内钙。蛋白激酶C先前被证明是流动诱导的PDGF表达中可能的主要介质，其至少部分似乎遵循c-fos的诱导机制，表明c-fos和PDGF诱导之间可能存在联系。然而，显著抑制c-fos转录的c-fos反义处理未能阻断流动诱导的PDGF表达，表明流动诱导的c-fos表达可能在流动诱导的PDGF表达机制中不起重要作用。与稳定性流动相比，搏动性流动下c-fos和PDGF表达诱导的差异表明HUVEC中存在复杂的、流动介导的基因表达调控机制。由流动介导的这些原癌基因表达增加可能在调节长期细胞反应中起重要作用。
