G-protein-coupled OX1 orexin/hcrtr-1 hypocretin receptors induce caspase-dependent and -independent cell death through p38 Mitogen-/Stress-activated protein kinase
G-protein-coupled OX1 orexin/hcrtr-1 hypocretin receptors induce caspase-dependent and -independent cell death through p38 Mitogen-/Stress-activated protein kinase
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DOI：
10.1074/jbc.m508603200
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发表时间：
2006-01-13
影响因子：
4.8
通讯作者：
Kukkonen, JP
中科院分区：
文献类型：
--
作者：
Ammoun, S;Lindholm, D;Kukkonen, JP
我们以中国仓鼠卵巢细胞为模型系统，研究了OX1受体对细胞死亡的信号转导作用。OX1受体被食欲素-A刺激后，细胞死亡延迟，不依赖于细胞内钙离子浓度的升高。经典的丝裂原活化蛋白激酶(MAPK)通路ERK和p38被增食欲素-A强烈激活。P38是诱导细胞死亡所必需的，而ERK通路似乎具有保护性。在p38介导的细胞死亡中经常涉及的一个途径，即P53的激活，并不介导细胞死亡，因为没有P53的稳定或依赖于P53的转录活性的增加，并且显性负P53结构不抑制细胞死亡。在基础条件下，食欲素-A诱导的细胞死亡与紧密的染色质凝集有关，它需要从头开始的基因转录和蛋白质合成，这是程序性(凋亡)细胞死亡的经典特征。然而，尽管泛型半胱氨酸氨基转移酶抑制剂N-苄氧羰基-瓦尔-丙氨酸-天冬氨酸-(O-甲基)氟甲基酮(Z-VAD-fmk)完全抑制了半胱氨酸氨基转移酶的活性，但它并不能使细胞从增食欲素A诱导的死亡中解救出来。在Z-VAD-fmk存在下，增食欲素-A诱导的细胞死亡仍然依赖于p38和从头蛋白的合成，但不再需要基因转录。因此，半胱氨酸天冬氨酸氨基转移酶的抑制导致可选择的、基因转录无关的死亡途径的激活。综上所述，本研究指出了增食欲素受体介导的细胞死亡的机制，并通过提出一条从G蛋白偶联受体到细胞死亡的途径，增加了我们对G蛋白偶联受体信号在细胞死亡中作用的一般理解，该途径不依赖于P53和caspase的激活，而是通过p38丝裂原/应激激活的蛋白激酶实现的。
We have investigated the signaling of OX1 receptors to cell death using Chinese hamster ovary cells as a model system. OX1 receptor stimulation with orexin-A caused a delayed cell death independently of cytosolic Ca2+ elevation. The classical mitogen-activated protein kinase (MAPK) pathways, ERK and p38, were strongly activated by orexin-A. p38 was essential for induction of cell death, whereas the ERK pathway appeared protective. A pathway often implicated in the p38-mediated cell death, activation of p53, did not mediate the cell death, as there was no stabilization of p53 or increase in p53-dependent transcriptional activity, and dominant-negative p53 constructs did not inhibit cell demise. Under basal conditions, orexin-A-induced cell death was associated with compact chromatin condensation and it required de novo gene transcription and protein synthesis, the classical hallmarks of programmed (apoptotic) cell death. However, though the pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-(O-methyl) fluoromethyl ketone (Z-VAD-fmk) fully inhibited the caspase activity, it did not rescue the cells from orexin-A-induced death. In the presence of Z-VAD-fmk, orexin-A-induced cell death was still dependent on p38 and de novo protein synthesis, but it no longer required gene transcription. Thus, caspase inhibition causes activation of alternative, gene transcription-independent death pathway. In summary, the present study points out mechanisms for orexin receptor-mediated cell death and adds to our general understanding of the role of G-protein-coupled receptor signaling in cell death by suggesting a pathway from G-protein-coupled receptors to cell death via p38 mitogen-/stress-activated protein kinase independent of p53 and caspase activation.