Ishizuka S, Yano T, Hagiwara K, Sone M, Nihei H, Ozasa H, Horikawa S
Department of Pathological Biochemistry, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, 101-0062, Japan.
Biochem Biophys Res Commun. 1999 Jan 8;254(1):88-92. doi: 10.1006/bbrc.1998.9902.
In vitro data support that extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), members of mitogen-activated protein (MAP) kinases, mediate the signal transduction pathways responsible for the cell proliferation. However, in vivo role of these MAP kinases is poorly understood. Intramuscular injection of 50% glycerol solution induces acute renal failure in rats. This injury is known as a model of rhabdomyolysis in human. To investigate the molecular mechanism of the signaling pathway in this injury, we examined the role of ERK and JNK. After the glycerol injection JNK was rapidly and transiently activated at about 4 h, while the activation of ERK was gradually increased and the levels were sustained at least to 24 h. Next, we examined the expression of cell-cycle related proteins after the glycerol injection using Western blot analysis. The levels of proliferating cell nuclear antigen (PCNA) protein as a marker for cell proliferation were induced at 2 h and significantly increased to 24 h after the injection. In addition, cyclins D1, D2, and D3 as markers for G1 phase also increased with similar time courses. To examine whether activation of ERK and/or JNK are involved in the renal regeneration after the glycerol injection, we examined the effect of genistein, which is an inhibitor of tyrosine kinase, on the activation of ERK and JNK. Administration of genistein to rats with this injury decreased the activation of ERK, but not JNK. The induction of PCNA and cyclin D1 was also prevented by this treatment. In this condition, renal function was further worsened as compared to control rats. These results provide the first evidence that ERK may be involved in the repair process of renal tubules damaged by this injury.
体外实验数据表明，丝裂原活化蛋白（MAP）激酶家族成员细胞外信号调节激酶（ERK）和c-Jun氨基末端激酶（JNK）介导负责细胞增殖的信号转导通路。然而，这些MAP激酶在体内的作用却知之甚少。肌肉注射50%甘油溶液可诱导大鼠急性肾衰竭。这种损伤是人类横纹肌溶解症的一种模型。为了研究该损伤中信号通路的分子机制，我们检测了ERK和JNK的作用。甘油注射后，JNK在约4小时迅速短暂激活，而ERK的激活则逐渐增加且水平至少维持到24小时。接下来，我们使用蛋白质免疫印迹分析检测甘油注射后细胞周期相关蛋白的表达。作为细胞增殖标志物的增殖细胞核抗原（PCNA）蛋白水平在注射后2小时被诱导，并在24小时显著增加。此外，作为G1期标志物的细胞周期蛋白D1、D2和D3也随相似的时间进程增加。为了检测ERK和/或JNK的激活是否参与甘油注射后的肾脏再生，我们检测了酪氨酸激酶抑制剂染料木黄酮对ERK和JNK激活的影响。给患有这种损伤的大鼠施用染料木黄酮可降低ERK的激活，但不影响JNK。这种处理也阻止了PCNA和细胞周期蛋白D1的诱导。在这种情况下，与对照大鼠相比，肾功能进一步恶化。这些结果首次证明ERK可能参与了这种损伤所致肾小管的修复过程。
