Ohmoto Makoto, Matsumoto Ichiro, Yasuoka Akihito, Yoshihara Yoshihiro, Abe Keiko
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Mol Cell Neurosci. 2008 Aug;38(4):505-17. doi: 10.1016/j.mcn.2008.04.011. Epub 2008 May 2.
We established transgenic mouse lines expressing a transneuronal tracer, wheat germ agglutinin (WGA), under the control of mouse T1R3 gene promoter/enhancer. In the taste buds, WGA transgene was faithfully expressed in T1R3-positive sweet/umami taste receptor cells. WGA protein was transferred not laterally to the synapse-bearing, sour-responsive type III cells in the taste buds but directly to a subset of neurons in the geniculate and nodose/petrosal ganglia, and further conveyed to a rostro-central region of the nucleus of solitary tract. In addition, WGA was expressed in solitary chemoreceptor cells in the nasal epithelium and transferred along the trigeminal sensory pathway to the brainstem neurons. The solitary chemoreceptor cells endogenously expressed T1R3 together with bitter taste receptors T2Rs. This result shows an exceptional signature of receptor expression. Thus, the t1r3-WGA transgenic mice revealed the sweet/umami gustatory pathways from taste receptor cells and the trigeminal neural pathway from solitary chemoreceptor cells.
我们构建了在小鼠T1R3基因启动子/增强子控制下表达跨神经元示踪剂小麦胚凝集素（WGA）的转基因小鼠品系。在味蕾中，WGA转基因在T1R3阳性的甜味/鲜味味觉受体细胞中得到忠实表达。WGA蛋白并非横向转移至味蕾中带有突触的酸味响应性III型细胞，而是直接转移至膝状神经节和结状/岩状神经节中的一部分神经元，并进一步传递至孤束核的 rostro - 中央区域。此外，WGA在鼻上皮中的孤离化学感受细胞中表达，并沿着三叉神经感觉通路转移至脑干神经元。孤离化学感受细胞内源性地同时表达T1R3和苦味受体T2Rs。这一结果显示了受体表达的独特特征。因此，t1r3 - WGA转基因小鼠揭示了从味觉受体细胞出发的甜味/鲜味味觉通路以及从孤离化学感受细胞出发的三叉神经通路。
