Analysis of mutant platelet-derived growth factor receptors expressed in PC12 cells identifies signals governing sodium channel induction during neuronal differentiation
Analysis of mutant platelet-derived growth factor receptors expressed in PC12 cells identifies signals governing sodium channel induction during neuronal differentiation
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DOI：
10.1128/mcb.17.1.89
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发表时间：
1997-01-01
影响因子：
5.3
通讯作者：
Maue, RA
中科院分区：
文献类型：
--
作者：
Fanger, GR;Vaillancourt, RR;Maue, RA
调控神经元分化的机制，包括神经营养因子诱导电压依赖性钠(Na+)通道表达的信号，不依赖RAS活性而发生，目前还不清楚。因此，分析了稳定表达血小板衍生生长因子(PDGF)β受体的PC12细胞亚系的Na+通道诱导，突变消除了特定信号分子的激活。核糖核酸酶保护实验和全细胞膜片钳记录表明，消除磷脂酰肌醇3-激酶(PI3K)、磷脂酶C-伽马(PLC(Gamma))、GTP酶激活蛋白(GAP)和SYP磷酸酶的突变并不能减少PDGF诱导的II型Na+通道α亚单位mRNA和功能性Na+通道的表达。然而，当受体激活时，结合Src家族成员的膜旁酪氨酸突变抑制了功能性Na+通道的诱导，而保持了II型α亚单位mRNA的诱导不变。膜旁酪氨酸的突变与消除PI3K、PLC伽马、GAP和SYP激活的突变相结合，取消了II型α亚单位mRNA的诱导，这表明至少部分冗余的信号机制介导了这种诱导。受体突变对Na+通道表达的不同影响并不反映受体信号转导能力的全球变化，因为在所有分析的突变受体中，c-fos和Transin mRNAs的诱导仍然发生。这些结果揭示了Src家族在诱导Na+通道表达中的重要作用，并强调了调控神经元分化的信号机制的多样性和组合性。
The mechanisms governing neuronal differentiation, including the signals underlying the induction of voltage-dependent sodium (Na+) channel expression by neurotrophic factors, which occurs independent of Ras activity, are not well understood. Therefore, Na+ channel induction was analyzed in sublines of PC12 cells stably expressing platelet-derived growth factor (PDGF) beta receptors with mutations that eliminate activation of specific signaling molecules. Mutations eliminating activation of phosphatidylinositol 3-kinase (PI3K), phospholipase C-gamma (PLC(gamma)), the GTPase-activating protein (GAP), and Syp phosphatase failed to diminish the inducation of type II Na+ channel alpha-subunit mRNA and functional Na+ channel expression by PDGF, as determined by RNase protection assays and whole-cell patch clamp recording. However, mutation of juxtamembrane tyrosines that bind members of the Src family of kinases upon receptor activation inhibited the induction of functional Na+ channels while leaving the induction of type II alpha-subunit mRNA intact. Mutation of juxtamembrane tyrosines in combination with mutations eliminating activation of PI3K, PLC gamma, GAP, and Syp abolished the induction of type II alpha-subunit mRNA, suggesting that at Least partially redundant signaling mechanisms mediate this induction. The differential effects of the receptor mutations on Na+ channel expression did not reflect global changes in receptor signaling capabilities, as in all of the mutant receptors analyzed, the induction of c-fos and transin mRNAs still occurred. The results reveal an important role for the Src family in the induction of Na+ channel expression and highlight the multiplicity and combinatorial nature of the signaling mechanisms governing neuronal differentiation.