Li Y S, Shyy J Y, Li S, Lee J, Su B, Karin M, Chien S
Department of Bioengineering, Institute for Biomedical Engineering, University of California, San Diego, La Jolla 92093, USA.
Mol Cell Biol. 1996 Nov;16(11):5947-54. doi: 10.1128/MCB.16.11.5947.
Hemodynamic forces play a key role in inducing atherosclerosis-implicated gene expression in vascular endothelial cells. To elucidate the signal transduction pathway leading to such gene expression, we studied the effects of fluid shearing on the activities of upstream signaling molecules. Fluid shearing (shear stress, 12 dynes/cm2 [1 dyne = 10(-5)N]) induced a transient and rapid activation of p21ras and preferentially activated c-Jun NH2 terminal kinases (JNK1 and JNK2) over extracellular signal-regulated kinases (ERK-1 and ERK-2). Cotransfection of RasN17, a dominant negative mutant of Ha-Ras, attenuated the shear-activated JNK and luciferase reporters driven by 12-O-tetradecanoylphorbol-13-acetate-responsive elements. JNK(K-R) and MEKK(K-M), the respective catalytically inactive mutants of JNK1 and MEKK, also partially inhibited the shear-induced luciferase reporters. In contrast, Raf301, ERK(K71R), and ERK(K52R), the dominant negative mutants of Raf-1, ERK-1, and ERK-2, respectively, had little effect on the activities of these reporters. The activation of JNK was also correlated with increased c-Jun transcriptional activity, which was attenuated by a negative mutant of Son of sevenless. Thus, mechanical stimulation exerted by fluid shearing activates primarily the Ras-MEKK-JNK pathway in inducing endothelial gene expression.
血流动力学力在诱导血管内皮细胞中与动脉粥样硬化相关的基因表达方面起着关键作用。为了阐明导致这种基因表达的信号转导途径，我们研究了流体剪切对上游信号分子活性的影响。流体剪切（剪切应力，12达因/平方厘米[1达因 = 10^(-5)牛]）诱导p21ras的瞬时快速激活，并且相较于细胞外信号调节激酶（ERK - 1和ERK - 2），优先激活c - Jun氨基末端激酶（JNK1和JNK2）。Ha - Ras的显性负突变体RasN17的共转染减弱了由12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯反应元件驱动的剪切激活的JNK和荧光素酶报告基因。JNK1和MEKK各自的催化失活突变体JNK(K - R)和MEKK(K - M)也部分抑制了剪切诱导的荧光素酶报告基因。相反，Raf - 1、ERK - 1和ERK - 2的显性负突变体Raf301、ERK(K71R)和ERK(K52R)对这些报告基因的活性影响很小。JNK的激活也与c - Jun转录活性的增加相关，而这种增加被Sevenless之子的负突变体减弱。因此，流体剪切施加的机械刺激在诱导内皮基因表达中主要激活Ras - MEKK - JNK途径。
