Mechanisms underlying TNF-alpha effects on agonist-mediated calcium homeostasis in human airway smooth muscle cells
Mechanisms underlying TNF-alpha effects on agonist-mediated calcium homeostasis in human airway smooth muscle cells
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DOI：
10.1152/ajplung.1997.273.5.l1020
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发表时间：
1997-11-01
影响因子：
4.9
通讯作者：
Panettieri, RA
中科院分区：
文献类型：
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作者：
Amrani, Y;Krymskaya, V;Panettieri, RA
我们之前已经表明，肿瘤坏死因子(TNF)- α，一种参与哮喘的细胞因子，增强了培养的人气道平滑肌（ASM）细胞对支气管收缩剂的Ca2+反应性。在本研究中，我们研究了tnf - α调节ASM细胞对这些药物的反应的潜在机制。在携带fura 2的人ASM细胞中，tnf - α和白细胞介素(IL)-1 β显著增强凝血素和缓激素引起的细胞内Ca2+升高。在tnf α处理的细胞中，凝血酶和缓激素的Ca2+响应分别为350 +/- 14和573 +/- 93 nM，而未处理的细胞中分别为130 +/- 17和247 +/- 48 nM （P < 0.0001）。在IL-1 β处理的细胞中，Ca2+对缓激肽的反应为350 +/- 21 nM，而未处理的细胞为127 +/- 12 nM （P < 0.0001）。tnf - α增强激动剂诱导的Ca2+反应的时间过程至少需要6小时，在孵育12小时后达到最大值。此外，环己亚胺，一种蛋白质合成抑制剂，完全阻断了tnf - α对Ca2+信号的增强作用。我们还发现，tnf - α显著增强了缓激素诱导的磷酸肌肽（PI）积累的增加。在3 × 10（-9）至3 × 10(-6) M缓激素作用下，对照细胞中PI积累的变化百分比为115 +/- 8至210 +/- 15%，而在tnf α处理的细胞中，PI积累的变化百分比为128 +/- 10至437 +/- 92%。PI转化为10mm NaF （G蛋白的直接激活剂）也被发现被tnf - α增强。与对照组相比，PI积累的变化百分比从对照细胞的280 +/- 35%增加到tnf - α处理细胞的437 +/- 92%。综上所述，这些结果表明tnf - α可以通过激活依赖于蛋白质合成的途径，有效调节ASM细胞中G蛋白介导的信号转导。我们的研究揭示了细胞因子在人ASM细胞中诱导Ca2+对支气管收缩剂反应增强的一种潜在机制。
We have previously shown that tumor necrosis factor (TNF)-alpha, a cytokine involved in asthma, enhances Ca2+ responsiveness to bronchoconstrictor agents in cultured human airway smooth muscle (ASM) cells. In the present study we investigated the potential mechanism(s) by which TNF-alpha modulates ASM cell responsiveness to such agents. In human ASM cells loaded with fura 2, TNF-alpha and interleukin (IL)-1 beta significantly enhanced thrombin-and bradykinin-evoked elevations of intracellular Ca2+. In TNF-alpha-treated cells, Ca2+ responses to thrombin and bradykinin were 350 +/- 14 and 573 +/- 93 nM vs. 130 +/- 17 and 247 +/- 48 nM in nontreated cells, respectively (P < 0.0001). In IL-1 beta-treated cells, the Ca2+ response to bradykinin was 350 +/- 21 vs. 127 +/- 12 nM in nontreated cells (P < 0.0001). The time course for TNF-alpha potentiation of agonist-induced Ca2+ responses requires a minimum of 6 h and was maximum after 12 h of incubation. In addition, cycloheximide, a protein synthesis inhibitor, completely blocked the potentiating effect of TNF-alpha on Ca2+ signals. We also found that TNF-alpha significantly enhanced increases in phosphoinositide (PI) accumulation induced by bradykinin. The percentage ofchange in PI accumulation over control was 115 +/- 8 to 210 +/- 15% in control cells vs. 128 +/- 10 to 437 +/- 92% in TNF-alpha-treated cells for 3 x 10(-9) to 3 x 10(-6) M bradykinin. The PI turnover to 10 mM NaF, a direct activator of G proteins, was also found to be enhanced by TNF-alpha. The percentage of change in PI accumulation over control increased from 280 +/- 35% in control cells to 437 +/- 92% in TNF-alpha-treated cells. Taken together, these results show that TNF-alpha can potently regulate G protein-mediated signal transduction in ASM cells by activating pathways dependent on protein synthesis. Our study demonstrates one potential mechanism underlying the enhanced Ca2+ response to bronchoconstrictor agents induced by cytokines in human ASM cells.