Fu J, Tay S S W, Ling E A, Dheen S T
Molecular Neurobiology Laboratory, Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Diabetologia. 2006 May;49(5):1027-38. doi: 10.1007/s00125-006-0153-3. Epub 2006 Mar 1.
AIMS/HYPOTHESIS: Maternal diabetes induces neural tube defects during embryogenesis. Since the neural tube is derived from neural stem cells (NSCs), it is hypothesised that in diabetic pregnancy neural tube defects result from altered expression of developmental control genes, leading to abnormal proliferation and cell-fate choice of NSCs.
Cell viability, proliferation index and apoptosis of NSCs and differentiated cells from mice exposed to physiological or high glucose concentration medium were examined by a tetrazolium salt assay, 5-bromo-2'-deoxyuridine incorporation, terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling and immunocytochemistry. Expression of developmental genes, including sonic hedgehog (Shh), bone morphogenetic protein 4 (Bmp4), neurogenin 1/2 (Neurog1/2), achaete-scute complex-like 1 (Ascl1), oligodendrocyte transcription factor 1 (Olig1), oligodendrocyte lineage transcription factor 2 (Olig2), hairy and enhancer of split 1/5 (Hes1/5) and delta-like 1 (Dll1), was analysed by real-time RT-PCR. Proliferation index and neuronal specification in the forebrain of embryos at embryonic day 11.5 were examined histologically.
High glucose decreased the proliferation of NSCs and differentiated cells. The incidence of apoptosis was increased in NSCs treated with high glucose, but not in the differentiated cells. High glucose also accelerated neuronal and glial differentiation from NSCs. The decreased proliferation index and early differentiation of neurons were evident in the telencephalon of embryos derived from diabetic mice. Exposure to high glucose altered the mRNA expression levels of Shh, Bmp4, Neurog1/2, Ascl1, Hes1, Dll1 and Olig1 in NSCs and Shh, Dll1, Neurog1/2 and Hes5 in differentiated cells.
CONCLUSIONS/INTERPRETATION: The changes in proliferation and differentiation of NSCs exposed to high glucose are associated with altered expression of genes that are involved in cell-cycle progression and cell-fate specification during neurulation. These changes may form the basis for the defective neural tube patterning observed in embryos of diabetic pregnancies.
目的/假设：母体糖尿病在胚胎发育过程中会诱发神经管缺陷。由于神经管源自神经干细胞（NSC），因此推测在糖尿病妊娠中，神经管缺陷是由发育控制基因表达改变所致，进而导致神经干细胞的增殖异常和细胞命运选择异常。
通过四氮唑盐检测、5-溴-2'-脱氧尿苷掺入、末端脱氧核苷酸转移酶介导的dUTP缺口末端标记和免疫细胞化学，检测暴露于生理或高葡萄糖浓度培养基中的小鼠神经干细胞及分化细胞的细胞活力、增殖指数和凋亡情况。通过实时逆转录聚合酶链反应分析发育基因的表达，这些基因包括音猬因子（Shh）、骨形态发生蛋白4（Bmp4）、神经生成素1/2（Neurog1/2）、achaete-scute复合体样蛋白1（Ascl1）、少突胶质细胞转录因子1（Olig1）、少突胶质细胞谱系转录因子2（Olig2）、毛状分裂增强子1/5（Hes1/5）和Delta样蛋白1（Dll1）。组织学检查胚胎第11.5天前脑的增殖指数和神经元分化情况。
高葡萄糖降低了神经干细胞及分化细胞的增殖。高葡萄糖处理的神经干细胞凋亡发生率增加，但分化细胞未增加。高葡萄糖还加速了神经干细胞向神经元和神经胶质细胞的分化。糖尿病小鼠胚胎端脑神经元的增殖指数降低和早期分化明显。暴露于高葡萄糖会改变神经干细胞中Shh、Bmp4、Neurog1/2、Ascl1、Hes1、Dll1和Olig1以及分化细胞中Shh、Dll1、Neurog1/2和Hes5的mRNA表达水平。
结论/解读：暴露于高葡萄糖的神经干细胞增殖和分化变化与神经形成过程中参与细胞周期进程和细胞命运决定的基因表达改变有关。这些变化可能是糖尿病妊娠胚胎中观察到的神经管模式缺陷的基础。
