Osmotic cell swelling-induced ATP release mediates the activation of extracellular signal-regulated protein kinase (Erk)-1/2 but not the activation of osmo-sensitive anion channels
Osmotic cell swelling-induced ATP release mediates the activation of extracellular signal-regulated protein kinase (Erk)-1/2 but not the activation of osmo-sensitive anion channels
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DOI：
10.1042/0264-6021:3430579
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发表时间：
1999-11-01
影响因子：
4.1
通讯作者：
Tilly, BC
中科院分区：
文献类型：
--
作者：
van der Wijk, T;de Jonge, HR;Tilly, BC
人肠407细胞通过快速释放ATP到细胞外介质中来响应低渗应激。激活的时间过程以及对细胞松弛素B处理和BAPTA-AM [1，2-双-（2-氨基苯氧基）乙烷-N，N，N '，N'-四乙酸乙酰氧基甲酯]负载的敏感性的差异表明ATP通过不同于体积调节阴离子通道的途径离开细胞。为了评估一个假定的作用，核苷酸作为自分泌/旁分泌因子的渗透信号，细胞外ATP的调节体积敏感性阴离子通道以及低渗诱导的激活细胞外信号调节蛋白激酶（ERK-1/2）的影响进行了研究。微摩尔浓度的ATP本身不能引起I-125（-）-负载细胞的同位素流出，但通过Ca 2+依赖性机制强烈增强低渗引起的阴离子流出。核苷酸的效力顺序（ATP = UTP = ATP[S] > ADP = AMP远大于腺苷= cAMP）表明P2 Y（2）受体参与。与此相反，毫摩尔浓度的ATP显着抑制的同位素流出和全细胞Cl-电流。抑制全细胞Cl-电流，不仅由毫摩尔ATP，但也由嘌呤受体拮抗剂苏拉明和活性蓝，观察到最显着的去极化保持电位，这表明直接与体积敏感的Cl-通道，而不是相互作用与嘌呤受体。ATP和UTP，在亚微摩尔水平，被发现作为有效的激活剂的Erk-1/2在肠407细胞。加入ATP水解酶腺苷三磷酸双磷酸酶的浴大大降低了低渗诱导的Erk-1/2激活，但不影响肿胀诱导的同位素流出，或全细胞Cl-电流。此外，用苏拉明或活性蓝预处理几乎完全阻止了Erk-1/2的低渗激活。结果表明，细胞外释放的ATP作为自分泌/旁分泌因子介导低渗诱导的Erk-1/2激活，但不作为体积敏感性代偿性Cl-电流的激活剂。
Human intestine 407 cells respond to hypo-osmotic stress by the rapid release of ATP into the extracellular medium. A difference in the time course of activation as well as in the sensitivity to cytochalasin B treatment and BAPTA-AM [1,2-bis-(2-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid acetoxymethyl ester] loading suggests that ATP leaves the cell through a pathway distinct from volume-regulated anion channels. To evaluate a putative role for nucleotides as autocrinic/paracrinic factors in osmotic signalling, the effects of extracellular ATP on the regulation of volume-sensitive anion channels as well as on the hypotonicity-induced activation of extracellular signal-regulated protein kinases (Erk-1/2) were investigated. Micromolar concentrations of ATP were unable to elicit an isotope efflux from I-125(-)-loaded cells by itself, but strongly potentiated the hypotonicity-provoked anion efflux through a Ca2+-dependent mechanism. The order of potency of nucleotides (ATP = UTP = ATP[S] > ADP = AMP much greater than adenosine = cAMP) indicated the involvement of P2Y(2) receptors. In contrast, millimolar concentrations of ATP markedly inhibited both the osmotically induced isotope efflux and whole-cell Cl- currents. Inhibition of whole-cell Cl- currents, not only by millimolar ATP but also by the purinoceptor antagonists suramin and reactive blue, was observed most prominently at depolarizing holding potentials, suggesting a direct interaction with volume-sensitive Cl- channels rather than interaction with purinoceptors. Both ATP and UTP, at submicromolar levels, were found to act as potent activators of Erk-1/2 in intestine 407 cells. Addition of the ATP hydrolase apyrase to the bath greatly reduced the hypotonicity-induced Erk-1/2 activation, but did not affect the swelling-induced isotope efflux, or whole-cell Cl- currents. Furthermore, pre-treatment with suramin or reactive blue almost completely prevented the hypo-osmotic activation of Erk-1/2. The results indicate that extracellularly released ATP functions as an autocrinic/paracrinic factor that mediates hypotonicity-induced Erk-1/2 activation but does not serve as an activator of volume-sensitive compensatory Cl- currents.