CAMP AND INOSITOL 1,4,5-TRISPHOSPHATE INCREASE CA2+ IN HT-29 CELLS BY ACTIVATING DIFFERENT CA2+ INFLUX PATHWAYS
CAMP AND INOSITOL 1,4,5-TRISPHOSPHATE INCREASE CA2+ IN HT-29 CELLS BY ACTIVATING DIFFERENT CA2+ INFLUX PATHWAYS
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DOI：
10.1152/ajpcell.1994.267.3.c776
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发表时间：
1994-09-01
影响因子：
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通讯作者：
WELSH, MJ
中科院分区：
文献类型：
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作者：
DENNING, GM;CLARK, RA;WELSH, MJ
Ca ~（2+）在调节肠上皮细胞跨上皮液体和电解质转运中起重要作用。为了研究调节胞浆游离Ca 2+浓度（[Ca 2 +]（c））的机制，我们在肠上皮细胞系HT-29克隆19 A细胞中检测了分泌激动剂对[Ca 2 +]（c）的影响。我们发现，在加入腺苷3 '，5'-环一磷酸（cAMP）依赖性激动剂或D-肌肌醇1，4，5-三磷酸[Ins（1，4，5）P-3]依赖性激动剂卡巴胆碱后，[Ca ~（2+）]（c）增加。一些证据表明cAMP和Ins（1，4，5）P-3依赖性激动剂通过不同的途径起作用。首先，异丙肾上腺素和毛喉素增加cAMP的细胞水平，但不增加Ins（1，4，5）P-3，而卡巴胆碱增加细胞水平的Ins（1，4，5）P-3和刺激肌醇磷酸周转不增加cAMP。第二，卡巴胆碱通过刺激细胞内钙库释放钙和细胞外钙内流增加[Ca 2 +]（c）。相反，cAMP激动剂通过单独刺激Ca 2+内流增加[Ca 2 +]（c）。第三，对最大浓度的cAMP激动剂和卡巴胆碱的反应近似相加。无机钙通道阻断剂可抑制Ins（1，4，5）P-3依赖的Ca ~（2+）内流，但不抑制cAMP激动剂依赖的Ca ~（2+）内流。因此，在肠上皮细胞中，[Ca 2 +]（c）至少由两种不同的第二信使途径调节，涉及Ins（1，4，5）P-3或cAMP。此外，cAMP通过与Ins（1，4，5）P-3介导的途径不同的途径刺激细胞外Ca 2+的内流。
Ca2+ plays a central role in regulating transepithelial fluid and electrolyte transport in intestinal epithelial cells. To investigate the mechanisms regulating the cytosolic free Ca2+ concentration ([Ca2+](c)), we examined the effect of secretory agonists on [Ca2+](c) in the intestinal epithelial cell line HT-29 clone 19A cells. We found that [Ca2+](c) increased after addition of either adenosine 3',5'-cyclic monophosphate (cAMP)-dependent agonists or a D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P-3]-dependent agonist carbachol. Several lines of evidence suggest that cAMP- and Ins(1,4,5)P-3-dependent agonists act through separate pathways. First, isoproterenol and forskolin increased cellular levels of cAMP but not Ins(1,4,5)P-3, whereas carbachol increased cellular levels of Ins(1,4,5)P-3 and stimulated inositol phosphate turnover without increasing cAMP. Second, carbachol increased [Ca2+](c) by stimulating the release of Ca2+ from intracellular stores and influx of extracellular Ca2+. In contrast, cAMP agonists increased [Ca2+](c) by stimulating Ca2+ influx alone. Third, the responses to maximal concentrations of cAMP agonists and carbachol were approximately additive. Finally, Ins(1,4,5)P-3- but not cAMP agonist-dependent Ca2+ influx was inhibited by inorganic Ca2+ channel blockers. Thus, in intestinal epithelial cells, [Ca2+](c) is regulated by at least two different second-messenger pathways, involving Ins(1,4,5)P-3 or cAMP. In addition, cAMP stimulates influx of extracellular Ca2+ through a pathway distinct from that mediated by Ins(1,4,5)P-3.