OX1 orexin receptors activate extracellular signal-regulated kinase in Chinese hamster ovary cells via multiple mechanisms:: The role of Ca2+ influx in OX1 receptor signaling
OX1 orexin receptors activate extracellular signal-regulated kinase in Chinese hamster ovary cells via multiple mechanisms:: The role of Ca2+ influx in OX1 receptor signaling
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DOI：
10.1210/me.2004-0389
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发表时间：
2006-01-01
影响因子：
--
通讯作者：
Kukkonen, JP
中科院分区：
文献类型：
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作者：
Ammoun, S;Johansson, L;Kukkonen, JP
在中国仓鼠卵巢（CHO）细胞中异源表达的OX 1食欲素受体的激活导致ERK磷酸化（激活）快速、强烈和持久的增加。使用多种抑制剂和显性负结构的ERK信号通路的解剖表明Ras、蛋白激酶C、磷酸肌醇-3-激酶和Src的参与。最有趣的是，Ca 2+内流出现中央的ERK反应在CHO细胞，同样的重组neuro-2a细胞和培养的大鼠纹状体神经元。在CHO细胞中的详细研究表明，抑制受体和存储操作的Ca 2+内流途径可以完全减弱的响应，而单独抑制存储操作的Ca 2+内流途径或Ca 2+释放是无效的。如果受体操纵通路被阻断，外源性激活的储存操纵通路可以取代它的位置，并恢复OX 1受体与ERK的偶联。进一步的实验表明，Ca 2+内流本身可能不是ERK磷酸化所需的，但是通过内流升高的Ca 2+充当开关，使得OX 1受体能够偶联到级联，导致ERK磷酸化、cAMP升高和磷脂酶C活化。总之，数据表明，食欲素受体的主要耦合到Ca 2+内流允许他们耦合到其他信号通路;在耦合到Ca 2+内流的情况下，食欲素受体可以作为信号整合剂，通过利用其他Ca 2+内流途径。
Activation of OX1 orexin receptors heterologously expressed in Chinese hamster ovary ( CHO) cells led to a rapid, strong, and long-lasting increase in ERK phosphorylation ( activation). Dissection of the signal pathways to ERK using multiple inhibitors and dominant-negative constructs indicated involvement of Ras, protein kinase C, phosphoinositide-3- kinase, and Src. Most interestingly, Ca2+ influx appeared central for the ERK response in CHO cells, and the same was indicated in recombinant neuro-2a cells and cultured rat striatal neurons. Detailed investigations in CHO cells showed that inhibition of the receptor- and store-operated Ca2+ influx pathways could fully attenuate the response, whereas inhibition of the store-operated Ca2+ influx pathway alone or the Ca2+ release was ineffective. If the receptor-operated pathway was blocked, an exogenously activated store-operated pathway could take its place and restore the coupling of OX 1 receptors to ERK. Further experiments suggested that Ca2+ influx, as such, may not be required for ERK phosphorylation, but that Ca2+, elevated via influx, acts as a switch enabling OX 1 receptors to couple to cascades leading to ERK phosphorylation, cAMP elevation, and phospholipase C activation. In conclusion, the data suggest that the primary coupling of orexin receptors to Ca2+ influx allows them to couple to other signal pathways; in the absence of coupling to Ca2+ influx, orexin receptors can act as signal integrators by taking advantage of other Ca2+ influx pathways.