Sustained activation of extracellular-signal-regulated kinase 1 (ERK1) is required for the continued expression of cyclin D1 in G(1) phase
Sustained activation of extracellular-signal-regulated kinase 1 (ERK1) is required for the continued expression of cyclin D1 in G(1) phase
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DOI：
10.1042/bj3260061
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发表时间：
1997-08-15
影响因子：
4.1
通讯作者：
Baldassare, JJ
中科院分区：
文献类型：
--
作者：
Weber, JD;Raben, DM;Baldassare, JJ
在中国仓鼠胚胎成纤维细胞（IIC9细胞）中，血小板衍生生长因子（PDGF）刺激丝裂原活化蛋白激酶/细胞外信号调节激酶（MAP激酶/ERK）活性，但不刺激c-jun n-末端激酶（JNK）活性，并诱导G(1)期进展。ERK1的激活是双期的，并持续整个细胞周期的G(1)期。PDGF以时间依赖性的方式诱导细胞周期蛋白DI蛋白和mRNA水平。通过添加MEK1 （MAP激酶/ERK激酶1）激活的选择性抑制剂PD98059或转染显性阴性ERK1 （dnERK(-)）来抑制pdgf诱导的ERK1活性与生长停滞相关。相反，显性阴性JNK（dnJNK(-)）的表达不影响生长。有趣的是，添加PD98059或dnERK(-)，而不添加dnJNK(-)，导致细胞周期蛋白D1蛋白和mRNA水平急剧下降，同时细胞周期蛋白D1-细胞周期蛋白依赖性激酶活性下降。为了研究ERK1持续激活的重要性，在整个G中通过添加PD98059阻断ERK1活性(1)。PDGF处理后4小时，添加PD98059使ERK1活性降低到生长受阻的IIC9细胞的水平。在抑制ERK1第二持续期活性后1小时内，观察到cyclin D1 mRNA和蛋白表达的丧失。持续ERK1活性的破坏也导致G(1)生长停滞。这些数据为持续ERK活性在控制G(1)进展中的作用提供了证据，通过正向调节cyclin D1的持续表达，cyclin D1是一种已知正向调节G(1)进展的蛋白质。
In Chinese hamster embryo fibroblasts (IIC9 cells), platelet-derived growth factor (PDGF) stimulated mitogen-activated protein kinase/extracellular-signal-regulated kinase (MAP kinase/ERK) activity, but not that of c-jun N-terminal kinase (JNK), and induced G(1) phase progression. ERK1 activation was biphasic and was sustained throughout the G(1) phase of the cell cycle. PDGF induced cyclin DI protein and mRNA levels in a time-dependent manner. Inhibition of PDGF-induced ERK1 activity by the addition of a selective inhibitor of MEK1 (MAP kinase kinase/ERK kinase 1) activation, PD98059, or transfection with a dominant-negative ERK1 (dnERK(-)) was correlated with growth arrest. In contrast, growth was unaffected by expression of dominant-negative JNK (dnJNK(-)). Interestingly, addition of PD98059 or dnERK(-), but not dnJNK(-), resulted in a dramatic decrease in cyclin D1 protein and mRNA levels, concomitant with a decrease in cyclin D1-cyclin-dependent kinase activity. To investigate the importance of sustained ERK1 activation, ERK1 activity was blocked by the addition of PD98059 throughout G(1). Addition of PD98059 up to 4 h after PDGF treatment decreased ERK1 activity to the levels found in growth-arrested IIC9 cells. Loss of cyclin D1 mRNA and protein expression was observed within 1 h after inhibition of the second sustained phase of ERK1 activity. Disruption of sustained ERK1 activity also resulted in G(1) growth arrest. These data provide evidence for a role for sustained ERK activity in controlling G(1) progression through positive regulation of the continued expression of cyclin D1, a protein known to positively regulate G(1) progression.