Gi2 Signaling Enhances Proliferation of Neural Progenitor Cells in the Developing Brain*
Gi2 Signaling Enhances Proliferation of Neural Progenitor Cells in the Developing Brain*
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DOI：
10.1074/jbc.m406721200
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发表时间：
2004-09
影响因子：
4.8
通讯作者：
H. Shinohara;J. Udagawa;R. Morishita;H. Ueda;H. Otani;R. Semba;Kanefusa Kato;T. Asano
中科院分区：
文献类型：
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作者：
H. Shinohara;J. Udagawa;R. Morishita;H. Ueda;H. Otani;R. Semba;Kanefusa Kato;T. Asano
我们先前的研究表明，百日咳毒素敏感的G蛋白GI2选择性地定位于胚胎脑室区，那里的神经上皮细胞经历了活跃的增殖。为了阐明GI2在这个部位的作用，我们首先在胚胎14.5天通过宫外操作的方法将百日咳毒素注射到小鼠的侧脑室。胚胎18.5天的检查显示，注射百日咳毒素的胚胎大脑皮质较薄，由较少的组成细胞组成。溴脱氧尿嘧啶核苷标记显示，注射百日咳毒素的胚胎大脑皮层中溴脱氧尿嘧啶核苷阳性细胞数量较少，表明神经上皮细胞增殖受损。接下来，我们培养了大鼠胚胎大脑的神经前体细胞，并评估了几种已知在脑室区域表达的GI偶联受体激动剂的促有丝分裂作用。在被测试的激动剂中，内皮素通过内皮素-B受体在纤维连接蛋白存在的情况下最有效地刺激[~3H]胸腺嘧啶核苷的掺入。这与细胞外信号调节激酶的磷酸化有关，百日咳毒素部分抑制了内皮素刺激的DNA合成和细胞外信号调节激酶的磷酸化。将内皮素-3注入胚胎脑室增加了大脑皮层中溴脱氧尿苷阳性细胞的数量，而注射内皮素-B受体拮抗剂则减少了这些阳性细胞的数量。这些发现表明，GI2介导了来自内皮素-B受体等受体的信号，以维持发育中大脑的神经前体细胞的有丝分裂活性。
Our previous study showed that the pertussis toxin-sensitive G protein, Gi2, is selectively localized in the ventricular zone of embryonic brains, where the neuroepithelial cells undergo active proliferation. In order to clarify the role of Gi2 in this site, we first administered pertussis toxin by an exo-utero manipulation method into the lateral ventricle of mouse brain at embryonic day 14.5. Examination at embryonic day 18.5 revealed that pertussis toxin-injected embryos had brains with thinner cerebral cortices, made up of fewer constituent cells. Bromodeoxyuridine labeling revealed fewer numbers of bromodeoxyuridine-positive cells in the cerebral cortices of pertussis toxin-injected embryos, suggesting impaired proliferation of neuroepithelial cells. Next we cultured neural progenitor cells from rat embryonic brains and evaluated the mitogenic effects of agonists for several Gi-coupled receptors that are known to be expressed in the ventricular zone. Among agonists tested, endothelin most effectively stimulated the incorporation of [3H]thymidine in the presence of fibronectin, via the endothelin-B receptor. This was associated with phosphorylation of extracellular signal-regulated kinase, and pertussis toxin partially inhibited both endothelin-stimulated DNA synthesis and phosphorylation of extracellular signal-regulated kinase. Injection of endothelin-3 into the ventricle of embryonic brains increased numbers of bromodeoxyuridine-positive cells in the cerebral cortex, whereas injection of an endothelin-B receptor antagonist decreased them. These findings indicate that Gi2 mediates signaling from receptors such as the endothelin-B receptor to maintain mitogenic activity in the neural progenitor cells of developing brain.