Experimental Diabetes, Metabolism and Nutrition Section, Diabetes Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
Mol Cell Neurosci. 1991 Aug;2(4):351-60. doi: 10.1016/1044-7431(91)90066-w.
The brain is dependent on glucose as an energy source and thus requires the expression of glucose transporter proteins to enable passage of glucose across both the endothelial cells of the blood-brain barrier and the plasma membranes of neurons and glia. The GLUT 1 isoform of the facilitative glucose transporter family is expressed in the blood-brain barrier; however, the major glucose transporter isoform(s) in neurons and glia have not been identified. We have investigated the expression of glucose transporters in cultured rat cerebellar granule neurons. Two isoforms, GLUT1 and GLUT3, were detected by Western and Northern blot analyses. Expression of both isoforms increased as neurons differentiated in culture, corresponding to an increase in glucose uptake. Localization of glucose transporters by immunofluorescence indicated the presence of both isoforms in neuronal processes and in the cell body. GLUT1 was detected in both plasma membrane and cytoplasm, whereas GLUT3 appeared only in plasma membrane. Significant GLUT3 expression was also detected in the neuronal cell lines PC12 and NG108 but not in primary cultured glia or C6 glioma cells. Our findings indicate that, in the rat brain, GLUT3 expression is predominantly in neurons, suggesting that this isoform may play a major role in neuronal glucose transport.
大脑依赖葡萄糖作为能量来源，因此需要表达葡萄糖转运蛋白，以使葡萄糖能够穿过血脑屏障的内皮细胞和神经元和神经胶质细胞的质膜。易化葡萄糖转运蛋白家族的 GLUT1 同工型在血脑屏障中表达；然而，神经元和神经胶质细胞中的主要葡萄糖转运蛋白同工型尚未确定。我们研究了培养的大鼠小脑颗粒神经元中葡萄糖转运体的表达。Western 和 Northern 印迹分析检测到两种同工型，GLUT1 和 GLUT3。两种同工型的表达随着神经元在培养中的分化而增加，与葡萄糖摄取的增加相对应。通过免疫荧光定位葡萄糖转运体表明两种同工型均存在于神经元突起和细胞体中。GLUT1 存在于质膜和细胞质中，而 GLUT3 仅存在于质膜中。在神经元细胞系 PC12 和 NG108 中也检测到显著的 GLUT3 表达，但在原代培养的神经胶质细胞或 C6 神经胶质瘤细胞中未检测到。我们的发现表明，在大鼠脑中，GLUT3 的表达主要在神经元中，表明该同工型可能在神经元葡萄糖转运中起主要作用。
