Potassium-induced apoptosis in rat cerebellar granule cells involves cell-cycle blockade at the G1/S transition
Potassium-induced apoptosis in rat cerebellar granule cells involves cell-cycle blockade at the G1/S transition
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DOI：
10.1385/jmn:15:3:155
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发表时间：
2000-12-01
影响因子：
3.1
通讯作者：
Fernandez-Salguero, P
中科院分区：
文献类型：
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作者：
Martín-Romero, FJ;Santiago-Josefat, B;Fernandez-Salguero, P
在有丝分裂后小脑颗粒细胞中的神经元凋亡过程中，控制细胞周期的G1/S转换的调节剂的作用进行了分析，试图确定与转化细胞的共同控制机制。细胞周期蛋白D1及其相关的激酶活性CDK 4（细胞周期蛋白依赖性激酶4）是G1/S转换的主要调节因子。而细胞周期蛋白D1是复合物的调节亚基，CDK 4代表催化结构域，一旦激活，将磷酸化下游靶点，如视网膜母细胞瘤蛋白，允许细胞周期进展。在有血清存在的情况下，通过缺钾诱导大鼠小脑颗粒细胞凋亡。进行蛋白质印迹分析并测量蛋白激酶活性。随着细胞凋亡的进行，细胞活力的丧失与细胞周期蛋白D1蛋白水平的显著增加一致，而CDK 4表达基本保持不变。与细胞周期蛋白D1积累同步，细胞周期蛋白依赖性激酶抑制剂p27（Kip 1）急剧下降至20%正常值。细胞周期蛋白D1/CDK 4依赖性激酶活性在凋亡早期增加，在9-12 h达到最大值，48 h降至非常低的水平。细胞周期蛋白D1的主要下游靶点细胞周期蛋白E随着细胞周期蛋白D1/CDK 4依赖性激酶活性的降低而降低。我们认为，神经元凋亡发生通过参与控制的细胞周期的G1/S转换的蛋白质的功能改变。因此，有丝分裂后神经元的凋亡可能是由于响应于影响细胞活力的细胞外条件而重新进入细胞周期的失败尝试，并且它可能涉及与促进转化细胞增殖的机制类似的机制。
The role of regulators controlling the G1/S transition of the cell cycle was analyzed during neuronal apoptosis in post-mitotic cerebellar granule cells in an attempt to identify common mechanisms of control with transformed cells. Cyclin D1 and its associated kinase activity CDK4 (cyclin-dependent kinase 4) are major regulators of the G1/S transition. Whereas cyclin D1 is the regulatory subunit of the complex, CDK4 represents the catalytic domain that, once activated, will phosphorylate downstream targets such as the retinoblastoma protein, allowing cell-cycle progression. Apoptosis was induced in rat cerebellar granule cells by depleting potassium in presence of serum. Western-blot analyses were performed and protein kinase activities were measured. As apoptosis proceeded, loss in cell viability was coincident with a significant increase in cyclin D1 protein levels, whereas CDK4 expression remained essentially constant. Synchronized to cyclin D1 accumulation, cyclin-dependent kinase inhibitor p27(Kip1) drastically dropped to 20% normal values. Cyclin D1/CDK4-dependent kinase activity increased early during apoptosis, reaching a maximum at 9-12 h and decreasing to very low levels by 48 h. Cyclin E, a major downstream target of cyclin D1, decreased concomitantly to the reduction in cyclin D1/CDK4-dependent kinase activity. We suggest that neuronal apoptosis takes place through functional alteration of proteins involved in the control of the G1/S transition of the cell cycle. Thus, apoptosis in post-mitotic neurons could result from a failed attempt to re-enter cell cycle in response to extracellular conditions affecting cell viability and it could involve mechanisms similar to those that promote proliferation in transformed cells.