Activation of phospholipase C pathways by a synthetic chondroitin sulfate-E tetrasaccharide promotes neurite outgrowth of dopaminergic neurons
Activation of phospholipase C pathways by a synthetic chondroitin sulfate-E tetrasaccharide promotes neurite outgrowth of dopaminergic neurons
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DOI：
10.1111/j.1471-4159.2007.04849.x
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发表时间：
2007-10-01
影响因子：
4.7
通讯作者：
Nishi, Akinori
中科院分区：
文献类型：
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作者：
Sotogaku, Naoki;Tully, Sarah E.;Nishi, Akinori
在多巴胺能神经元中，硫酸软骨素（CS）蛋白聚糖在神经元的发育和再生中起着重要作用。然而，由于CS的复杂性和异质性，CS的精确结构与生物活性及其对多巴胺能神经元影响的分子机制知之甚少。在这项研究中，我们研究了合成CS寡糖和天然多糖促进中脑多巴胺能神经元突起生长的能力和CS激活的信号通路。CS-E多糖，而不是CSA，-C或-D多糖，促进多巴胺能神经元的突起生长在CS浓度在生理范围内。CS-E多糖对神经突起生长的刺激作用被软骨素酶ABC消化成二糖单位完全消除。与CS-E多糖类似，仅显示CS-E硫酸化基序的合成四糖刺激多巴胺能神经元的轴突生长，而CS-E二糖或未硫酸化四糖则没有影响。分子机制分析显示，CS-E四糖的作用是通过中期因子-多效生长因子/蛋白酪氨酸磷酸酶ζ和脑源性神经营养因子/酪氨酸激酶B受体途径介导的，随后激活两个细胞内磷脂酶C（PLC）信号级联：PLC/蛋白激酶C和PLC/肌醇1，4，5-三磷酸/肌醇1，4，5-三磷酸受体信号传导导致Ca（2+）钙调蛋白依赖性激酶II和钙调磷酸酶的细胞内Ca 2+浓度依赖性激活。这些结果表明，一个特定的硫酸化基序，特别是CS-E四糖单位，代表了一个关键的结构决定因素，激活中期因子，多效生长因子和脑源性神经营养因子介导的信号转导，并需要在多巴胺能神经元的轴突活性的CS。
In dopaminergic neurons, chondroitin sulfate (CS) proteoglycans play important roles in neuronal development and regeneration. However, due to the complexity and heterogeneity of CS, the precise structure of CS with biological activity and the molecular mechanisms underlying its influence on dopaminergic neurons are poorly understood. In this study, we investigated the ability of synthetic CS oligosaccharides and natural polysaccharides to promote the neurite outgrowth of mesencephalic dopaminergic neurons and the signaling pathways activated by CS. CS-E polysaccharide, but not CSA, -C or -D polysaccharide, facilitated the neurite outgrowth of dopaminergic neurons at CS concentrations within the physiological range. The stimulatory effect of CS-E polysaccharide on neurite outgrowth was completely abolished by its digestion into disaccharide units with chondroitinase ABC. Similarly to CS-E polysaccharide, a synthetic tetrasaccharide displaying only the CS-E sulfation motif stimulated the neurite outgrowth of dopaminergic neurons, whereas a CS-E disaccharide or unsulfated tetrasaccharide had no effect. Analysis of the molecular mechanisms revealed that the action of the CS-E tetrasaccharide was mediated through midkine-pleiotrophin/protein tyrosine phosphatase zeta and brain-derived neurotrophic factor/tyrosine kinase B receptor pathways, followed by activation of the two intracellular phospholipase C (PLC) signaling cascades: PLC/protein kinase C and PLC/ inositol 1,4,5-triphosphate/inositol 1,4,5-triphosphate receptor signaling leading to intracellular Ca2+ concentration-dependent activation of Ca(2+)calmodulin-dependent kinase II and calcineurin. These results indicate that a specific sulfation motif, in particular the CS-E tetrasaccharide unit, represents a key structural determinant for activation of midkine, pleiotrophin and brain-derived neurotrophic factor-mediated signaling, and is required for the neuritogenic activity of CS in dopaminergic neurons.