MT1 melatonin receptor internalization underlies melatonin-induced morphologic changes in Chinese hamster ovary cells and these processes are dependent on Gi proteins, MEK 1/2 and microtubule modulation
MT1 melatonin receptor internalization underlies melatonin-induced morphologic changes in Chinese hamster ovary cells and these processes are dependent on Gi proteins, MEK 1/2 and microtubule modulation
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DOI：
10.1111/j.1600-079x.2007.00525.x
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发表时间：
2008-04-01
影响因子：
10.3
通讯作者：
Witt-Enderby, Paula A.
中科院分区：
文献类型：
--
作者：
Bondi, C. Dominic;McKeon, Raelene M.;Witt-Enderby, Paula A.
褪黑素诱导多种细胞类型的细胞分化。数据显示，这些过程涉及多种机制，这些机制是细胞类型特异性的，可能是受体依赖或独立的。本研究的重点是利用mt1 -中国仓鼠卵巢（CHO）模型，专门评估人类MTI褪黑激素受体在细胞分化中的作用；一种可重复地产生可测量的形态变化以响应褪黑素的物质。通过多种方法，我们发现褪黑激素通过MEK 1/2和ERK 1/2依赖机制诱导MT1- cho细胞超伸长，该机制依赖于MT1受体Gi蛋白激活和网格蛋白介导的内吞作用。利用免疫沉淀分析，我们发现在褪黑激素存在的情况下，MTl受体与Gi(α) 2,3, Gq(α), β -arrestin-2， MEK 1/2和ERK 1/2形成复合物。我们还发现褪黑素诱导的MEK和ERK活性依赖于Gi蛋白激活、网格蛋白介导的内吞作用，并受微管调节。我们从这些研究中得出结论，褪黑激素诱导CHO细胞中MT1褪黑激素受体的内化负责激活MEK 1/2和ERK 1/2来驱动这些形态变化。褪黑素介导的这些事件需要Gi蛋白激活和网格蛋白介导的内吞作用，从而与β -arrestin-2/MEK 1/2和ERK 1/2形成MT1受体复合物。MT1-CHO模型对于绘制通过MTI受体介导的信号级联反应是非常宝贵的，特别是因为它将MTl受体的MEK/ERK 1/2激活与受体酪氨酸激酶的激活分离开来。
Melatonin induces cellular differentiation in numerous cell types. Data show that multiple mechanisms are involved in these processes that are cell-type specific and may be receptor dependent or independent. The focus of this study was to specifically assess the role of human MTI melatonin receptors in cellular differentiation using an MT1-Chinese hamster ovary (CHO) model; one that reproducibly produces measurable morphologic changes in response to melatonin. Using multiple approaches, we show that melatonin induces MT1-CHO cells to hyperelongate through a MEK 1/2, and ERK 1/2-dependent mechanism that is dependent upon MT1 receptor Gi protein activation, and clathrin-mediated endocytosis. internalization, Using immunoprecipitation analysis, we show that MTl receptors form complexes with Gi(alpha) 2,3, Gq(alpha), beta-arrestin-2, MEK 1/2, and ERK 1/2 in the presence of melatonin. We also show that MEK and ERK activity that is induced by melatonin is dependent on Gi protein activation, clathrin-mediated endocytosis and is modulated by microtubules. We conclude from these studies that melatonin-induced internalization of human MT1 melatonin receptors in CHO cells is responsible for activating both MEK 1/2 and ERK 1/2 to drive these morphologic changes. These events, as mediated by melatonin, require Gi protein activation and endocytosis mediated through clathrin, to form MT1 receptor complexes with beta-arrestin-2/MEK 1/2 and ERK 1/2. The MT1-CHO model is invaluable to mapping out signaling cascades as mediated through MTI receptors especially because it separates out MEK/ERK 1/2 activation by MTl receptors from that of receptor tyrosine kinases.