Molecular mechanism of apoptosis and differentiation in vascular smooth muscle cells: the role of c-Jun N-terminal kinase (JNK)

[目的]近年来的研究表明，血管平滑肌细胞的表型调控和凋亡是动脉粥样硬化的基础。血管平滑肌细胞的表型从以收缩蛋白高表达为特征的高度分化的收缩表型转变为以收缩蛋白低表达和蛋白质合成速率高为特征的合成表型。另一方面，血管平滑肌细胞的凋亡可能导致动脉壁平滑肌细胞层的丢失和动脉粥样硬化病变的不稳定。本课题旨在阐明丝裂原活化蛋白激酶（MAP激酶），尤其是c-Jun氨基末端激酶（JNK）在血管平滑肌细胞表型调控和凋亡中的作用。[结果]建立了高分化血管平滑肌细胞培养体系。血小板衍生生长因子（PDGF）引发动脉粥样硬化 ...更多信息 细胞毒性改变优先激活MAP激酶的ERK家族，而过氧化氢的氧化应激优先激活JNK，表明不同的MAP激酶亚家族介导响应于不同的细胞外刺激的细胞内信号传导。PDGF和过氧化氢都能引起培养的血管平滑肌细胞的去分化。此外，过氧化氢也引起细胞凋亡。我们制作了编码显性阴性和野生型JNK、显性阴性和组成型活性SEK 1和JNK通路上游调节因子MKK 7的腺病毒载体。这些腺病毒载体成功地转导了几乎100%的培养的血管平滑肌细胞。活性SEK 1的表达引起血管平滑肌细胞的去分化，部分模仿氧化应激的作用。我们还发现JNK通路在培养的成年心肌细胞凋亡中起着重要作用。我们利用基因芯片技术通过转录组分析鉴定了一组受JNK通路调控的基因。少

[ Aim ] Recent studies indicate that the phenotypic modulation and apoptosis of vascular smooth muscle are fundamental phenomena underlying atherosclerosis. Vascular smooth muscle cells change their phenotype from highly differentiated contractile phenotype that is characterized by high expression of contractile proteins to synthetic one that is characterized by low expression of contractile proteins and high rate of protein synthesis. On the other hand, apoptosis of vascular smooth muscle cells may cause the loss of smooth muscle cell layer form arterial wall and destabilization of atherosclerotic lesion. The aim of this project is to elucidate the role of mitogen-activated protein kinases (MAP kinases), especially c-Jun N-terminal kinase (JNK), in phenotypic modulation and apoptosis of vascular smooth muscle cells. [ Results ] We established highly differentiated vascular smooth muscle cell culture system as a model system. Platelet-derived growth factor (PDGF) that initiates atheros … More clerotic change preferentially activated ERK family of MAP kinases, whereas oxidative stress by hydrogen peroxide preferentially activated JNK, suggesting different MAP kinase subfamily are mediating intracellular signaling in response to different extracellular stimuli. Both PDGF and hydrogen peroxide caused dedifferentiation of vascular smooth muscle cells in culture. In addition, hydrogen peroxide also caused apoptotic cell death. We made adenoviral vectors encoding dominant negative and wild type JNK, dominant negative and constitutively active SEK1 and MKK7, the upstream regulator of JNK pathway. These adenoviral vectors successfully transduced almost 100 % of vascular smooth muscle cells in culture. Expression of active SEK1 caused dedifferentiation of vascular smooth muscle cells partly mimicking the effect of oxidative stress. We also found that JNK pathway plays a central role in apoptosis of adult cardiac myocytes in culture. We identified a group of genes that are regulated under the control of JNK pathway by transcriptome analyses using DNA microarray. Less