GTPase-deficient G alpha 16 and G alpha q induce PC12 cell differentiation and persistent activation of cJun NH2-terminal kinases.
GTPase-deficient G alpha 16 and G alpha q induce PC12 cell differentiation and persistent activation of cJun NH2-terminal kinases.
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GTPase 缺陷的 G α 16 和 G α q 诱导 PC12 细胞分化和 cJun NH2 末端激酶的持续激活。
DOI：
10.1128/mcb.16.2.648
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发表时间：
1996
影响因子：
5.3
通讯作者：
Maue,RA
中科院分区：
文献类型：
--
作者：
Heasley,LE;Storey,B;Fanger,GR;Butterfield,L;Zamarripa,J;Blumberg,D;Maue,RA
对特定蛋白激酶通路的持续刺激被认为是受体酪氨酸激酶和细胞内癌蛋白的关键特征，这些蛋白是大鼠嗜铬细胞瘤(PC12)细胞分化的信号。在迄今已发现的丝氨酸/苏氨酸激酶中，p42/44丝裂原活化蛋白(MAP)激酶因其在PC12细胞分化信号中的潜在作用而被重点关注。在此，我们报道了逆转录病毒介导的GTP酶缺陷、组成活性形式的异源三聚体Gq家族成员GαqQ209L和Gα16Q212L在PC12细胞中的表达诱导神经元分化，表现为轴突生长和电压依赖性钠通道表达增加。在GTP酶缺陷形式的αi2或αo的细胞表达后，没有观察到分化，这表明G蛋白的Gq家族具有选择性。正如预测的那样，αqQ209L和α16Q212L的过表达使PC12细胞的基础磷脂酶C活性增加了约10倍。值得注意的是，在用α16Q212L或αqQ209L分化的PC12细胞中，几乎没有检测到p42/44 MAPK活性，尽管这些蛋白在成分活性CRAF1的表达后被强烈激活。相反，在表达αqQ209L和α16Q212L的PC12细胞中观察到cJun氨基末端激酶(JNKs)的持续三倍激活。这种JNK活性水平与神经生长因子相似，神经生长因子是PC12细胞分化的强大诱导剂。支持JNK激活在PC12细胞分化中的作用，逆转录病毒介导的JNK靶点cJun在PC12细胞中过表达诱导轴突生长。这些结果明确了p42/44 MAP激酶非依赖于p12细胞分化的机制，并表明GTP酶缺陷的GαQ和Gα16亚单位持续激活Pro导向的蛋白激酶家族的JNK成员足以诱导PC12细胞分化。
Persistent stimulation of specific protein kinase pathways has been proposed as a key feature of receptor tyrosine kinases and intracellular oncoproteins that signal neuronal differentiation of rat pheochromocytoma (PC12) cells. Among the protein serine/threonine kinases identified to date, the p42/44 mitogen-activated protein (MAP) kinases have been highlighted for their potential role in signalling PC12 cell differentiation. We report here that retrovirus-mediated expression of GTPase-deficient, constitutively active forms of the heterotrimeric Gqfamily members, GαqQ209L and Gα16Q212L, in PC12 cells induces neuronal differentiation as indicated by neurite outgrowth and the increased expression of voltage-dependent sodium channels. Differentiation was not observed after cellular expression of GTPase-deficient forms of αi2or αo, indicating selectivity for the Gqfamily of G proteins. As predicted, overexpression of αqQ209L and α16Q212L constitutively elevated basal phospholipase C activity ~10-fold in PC12 cells. Significantly, little or no p42/44 MAP kinase activity was detected in PC12 cells differentiated with α16Q212L or αqQ209L, although these proteins were strongly activated following expression of constitutively active cRaf-1. Rather, a persistent threefold activation of the cJun NH2-terminal kinases (JNKs) was observed in PC12 cells expressing αqQ209L and α16Q212L. This level of JNK activation was similar to that achieved with nerve growth factor, a strong inducer of PC12 cell differentiation. Supportive of a role for JNK activation in PC12 cell differentiation, retrovirus-mediated over-expression of cJun, a JNK target, in PC12 cells induced neurite outgrowth. The results define a p42/44 MAP kinase-independent mechanism for differentiation of PC12 cells and suggest that persistent activation of the JNK members of the proline-directed protein kinase family by GTPase-deficient Gαqand Gα16subunits is sufficient to induce differentiation of PC12 cells.