Gammelsaeter R, Jenstad M, Bredahl M K L, Gundersen V, Chaudhry F A
The Centre for Molecular Biology and Neuroscience, University of Oslo, N-0317 Oslo, Norway.
Biochem Biophys Res Commun. 2009 Apr 10;381(3):378-82. doi: 10.1016/j.bbrc.2009.02.062. Epub 2009 Feb 20.
Insulin and glucagon secretion from the islets of Langerhans is highly regulated. Although an increased plasma glucose level is the major stimulus for insulin exocytosis, roles for glutamine and glutamate have been suggested. Interestingly, the islet cells display elements associated with synaptic transmission. In the central nervous system (CNS), glutamine transport by SN1 and SAT2 sustain the generation of neurotransmitter glutamate. We hypothesized that the same transporters are essential for glutamine transport into the islet cells and for subsequent formation of glutamate acting as an intracellular signaling molecule. We demonstrate that islet cells express several transporters which can mediate glutamine transport. In particular, we show pronounced expression of SN1 and SAT2 in B-cells and A-cells, respectively. The cell-specific expression of these transporters together with their functional characteristics suggest an important role for glutamine in the regulation of insulin secretion.
胰岛β细胞分泌胰岛素和胰高血糖素受到高度调节。尽管血浆葡萄糖水平升高是胰岛素胞吐作用的主要刺激因素，但已有研究表明谷氨酰胺和谷氨酸也发挥作用。有趣的是，胰岛细胞表现出与突触传递相关的成分。在中枢神经系统（CNS）中，SN1和SAT2介导的谷氨酰胺转运维持神经递质谷氨酸的生成。我们推测，相同的转运体对于谷氨酰胺转运进入胰岛细胞以及随后作为细胞内信号分子的谷氨酸的形成至关重要。我们证明胰岛细胞表达几种可介导谷氨酰胺转运的转运体。特别是，我们分别在B细胞和A细胞中发现了SN1和SAT2的显著表达。这些转运体的细胞特异性表达及其功能特性表明谷氨酰胺在胰岛素分泌调节中起重要作用。
