Activation of cyclic AMP signaling in Ae2-deficient mouse fibroblasts
Activation of cyclic AMP signaling in Ae2-deficient mouse fibroblasts
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DOI：
10.1074/jbc.m710590200
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发表时间：
2008-05-02
影响因子：
4.8
通讯作者：
Elferink, Ronald P. J. Oude
中科院分区：
文献类型：
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作者：
Mardones, Pablo;Medina, Juan F.;Elferink, Ronald P. J. Oude
阴离子交换剂2（AE 2，SLC 4A 2）是一种广泛表达的膜溶质载体，其通过将胞质碳酸氢盐交换为胞外氯化物来调节细胞内pH（pH（i））。我们使用来自Ae 2缺陷（Ae 2（a，B）（-/-））小鼠的成纤维细胞来研究静息细胞内pH（pH（i））的碱性偏移对cAMP信号传导和基因表达的激活的影响。在细胞外pH（pH（o））7.4和37摄氏度下，与野生型细胞相比，Ae 2（a，B）（-/-）成纤维细胞显示pH（i）增加（增加0.22 +/- 0.03单位）。静息pHi的这种变化与碳酸氢盐激活的可溶性腺苷酸环化酶表达的上调、cAMP产生的增加、Creb磷酸化、诱导性cAMP早期阻遏物1 mRNA表达以及毛喉素对c-Fos转录的激活受损有关。这些结果突出了通过Ae 2在维持培养的小鼠成纤维细胞中的pHi稳态中的碳酸氢盐转运的重要性，并揭示了cAMP在对慢性碱化的细胞应答中的作用，其中包括诱导型cAMP早期阻遏物1介导的磷酸化Creb活性的衰减。
Anion exchanger 2 (AE2, SLC4A2) is a ubiquitously expressed membrane solute carrier that regulates intracellular pH (pH(i)) by exchanging cytosolic bicarbonate for extracellular chloride. We used fibroblasts from Ae2-deficient (Ae2(a,b)(-/-)) mice to study the effects of an alkaline shift in resting intracellular pH (pH(i)) on the activation of cAMP signaling and gene expression. Ae2(a,b)(-/-) fibroblasts show increased pH(i) (by 0.22 +/- 0.03 unit) compared with wild type cells at extracellular pH (pH(o)) 7.4 and 37 degrees C. This shift in resting pHi is associated with an up-regulation of bicarbonate-activated soluble adenylyl cyclase expression, increased cAMP production, Creb phosphorylation, inducible cAMP early repressor 1 mRNA expression, and impaired activation of c-Fos transcription by forskolin. These results highlight the importance of bicarbonate transport via Ae2 in maintaining pHi homeostasis in cultured mouse fibroblasts and unveil the role of cAMP in the cellular response to chronic alkalization, which putatively includes an inducible cAMP early repressor 1-mediated attenuation of phosphorylated Creb activity.