Research for requirement of down-regulation of energy metabolism for neuronal differentiation

只有少数人神经母细胞瘤细胞系保持神经分化的潜力。我们偶然注意到，包括SH-SY5Y在内的可分化的人类神经母细胞瘤的二氢硫胺-琥珀酸基转移酶(DLST)基因存在一种特殊的突变，其产物是参与线粒体能量代谢的α-酮戊二酸-脱氢酶复合体的一部分。在这里，我们证明了通过恢复SH-SY5Y的野生型DLST基因来降低能量对神经元分化的要求。DLST活性上调增加线粒体膜电位，损害神经元分化。通过能量代谢抑制剂的治疗，这种损伤部分得到了恢复。此外，用小干扰RNA下调DLST的表达可促进大鼠嗜铬细胞瘤PC12和原代培养的新皮质细胞的神经元分化。我们进一步发现SH-SY5Y细胞之间的线粒体膜电位是不均匀的，在神经母细胞型细胞中线粒体膜电位较低。因此，随机突变赋予了神经母细胞瘤分化的潜力，这表明这种突变已被优先选择作为神经元分化的模型细胞系。能量的降低似乎通过阻止细胞死亡来促进分化。这些结果为神经元分化提供了新的视角。

Only a few human neuroblastoma cell-lines maintain the potential for neuronal differentiation. We noticed by chance that differentiable human neuroblastomas including SH-SY5Y have a specific mutation in the dihydrolipoamide-succinyltransferase (DLST) gene, whose product is a component of the α-ketoglutarate-dehydrogenase complex involved in mitochondrial energy metabolism. Here we demonstrate a requirement of energy-reduction for neuronal differentiation by restoring SH-SY5Y with the wild-type DLSTgene. Up-regulation of DLST activity increased mitochondrial membrane potential and impaired neuronal differentiation. The impairment was partially rescued by treatment with inhibitors of energy metabolism. Additionally, down-regulation of DLST expression with small interfering RNA enhanced neuronal differentiation in rat pheochromocytoma PC12 and primary cultured neocortical cells. We further found that mitochondrial membrane potential among SH-SY5Y cells was heterogeneous and lower in neuroblastic type cells. It is thus concluded that the casual mutation conferred the potential for differentiation on the neuroblastomas, suggesting that such mutants had been preferentially selected as a model cell-line for neuronal differentiation. The energy-reduction seemed to contribute to the differentiation by preventing cell-death. These results provide a new insight into neuronal differentiation.