Insulin-like growth factor-1-dependent maintenance of neuronal metabolism through the phosphatidylinositol 3-kinase-Akt pathway is inhibited by C2-ceramide in CAD cells
Insulin-like growth factor-1-dependent maintenance of neuronal metabolism through the phosphatidylinositol 3-kinase-Akt pathway is inhibited by C2-ceramide in CAD cells
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DOI：
10.1111/j.1460-9568.2007.05557.x
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发表时间：
2007-05-01
影响因子：
3.4
通讯作者：
Gibson, Rosemary M.
中科院分区：
文献类型：
--
作者：
Arboleda, Gonzalo;Huang, Tze-Jen;Gibson, Rosemary M.
神经酰胺是响应于与神经变性相关的刺激而产生的脂质第二信使，其诱导细胞凋亡，这是帕金森病中神经元死亡的潜在机制。我们测试了胰岛素样生长因子-1（IGF-1）可以介导CAD细胞中的代谢反应的假设，CAD细胞是一种中脑起源的多巴胺能细胞系，其在去除血清后分化成神经元样表型，延伸类似神经突的过程，合成丰富的多巴胺和去甲肾上腺素，并表达儿茶酚胺能生物合成酶酪氨酸羟化酶和多巴胺β-羟化酶，这一过程是磷脂酰肌醇3-激酶（PI 3-K）-Akt依赖性的，可被C-2-神经酰胺抑制。使用微生理测量法将代谢反应评价为细胞外酸化率（ECAR）的实时变化。IGF-1诱导的ECAR反应与糖酵解增加相关，通过增加NAD（P）H还原、升高的己糖激酶活性和Akt磷酸化来确定。C-2-神经酰胺以剂量依赖性方式抑制所有这些变化，并且是特异性的，因为它不是由无活性的C-2-神经酰胺类似物C-2-二氢神经酰胺诱导的。与C-2-神经酰胺类似，上游激酶PI 3-K的抑制也会抑制Akt磷酸化和对IGF-1的代谢反应。Akt磷酸化丧失后，线粒体膜电位降低。这些结果表明，IGF-1可以通过PI 3-K-Akt快速调节神经元代谢，并且C-2-神经酰胺诱导的早期代谢抑制涉及PI 3-K-Akt通路的阻断，并且可能损害糖酵解的第一步。这可能代表了C-2-神经酰胺诱导的细胞死亡途径中的一个新的早期事件，其可以协调线粒体的后续变化和神经元凋亡的承诺。
Ceramide is a lipid second-messenger generated in response to stimuli associated with neurodegeneration that induces apoptosis, a mechanism underlying neuronal death in Parkinson's disease. We tested the hypothesis that insulin-like growth factor-1 (IGF-1) could mediate a metabolic response in CAD cells, a dopaminergic cell line of mesencephalic origin that differentiate into a neuronal-like phenotype upon serum removal, extend processes resembling neurites, synthesize abundant dopamine and noradrenaline and express the catecholaminergic biosynthetic enzymes tyrosine hydroxylase and dopamine beta-hydroxylase, and that this process was phosphatidylinositol 3-kinase (PI 3-K)-Akt-dependent and could be inhibited by C-2-ceramide. The metabolic response was evaluated as real-time changes in extracellular acidification rate (ECAR) using microphysiometry. The IGF-1-induced ECAR response was associated with increased glycolysis, determined by increased NAD(P)H reduction, elevated hexokinase activity and Akt phosphorylation. C-2-ceramide inhibited all these changes in a dose-dependent manner, and was specific, as it was not induced by the inactive C-2-ceramide analogue C-2-dihydroceramide. Inhibition of the upstream kinase, PI 3-K, also inhibited Akt phosphorylation and the metabolic response to IGF-1, similar to C-2-ceramide. Decreased mitochondrial membrane potential occurred after loss of Akt phosphorylation. These results show that IGF-1 can rapidly modulate neuronal metabolism through PI 3-K-Akt and that early metabolic inhibition induced by C-2-ceramide involves blockade of the PI 3-K-Akt pathway, and may compromise the first step of glycolysis. This may represent a new early event in the C-2-ceramide-induced cell death pathway that could coordinate subsequent changes in mitochondria and commitment of neurons to apoptosis.