Section of Oral Neuroscience, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
Monell Chemical Senses Center, Philadelphia, PA, United States of America.
PLoS One. 2019 Nov 12;14(11):e0225190. doi: 10.1371/journal.pone.0225190. eCollection 2019.
Expression of insulin and its receptor (IR) in rodent taste cells has been proposed, but exactly which types of taste cells express IR and the function of insulin signaling in taste organ have yet to be determined. In this study, we analyzed expression of IR mRNA and protein in mouse taste bud cells in vivo and explored its function ex vivo in organoids, using RT-PCR, immunohistochemistry, and quantitative PCR. In mouse taste tissue, IR was expressed broadly in taste buds, including in type II and III taste cells. With using 3-D taste bud organoids, we found insulin in the culture medium significantly decreased the number of taste cell and mRNA expression levels of many taste cell genes, including nucleoside triphosphate diphosphohydrolase-2 (NTPDase2), Tas1R3 (T1R3), gustducin, carbonic anhydrase 4 (CA4), glucose transporter-8 (GLUT8), and sodium-glucose cotransporter-1 (SGLT1) in a concentration-dependent manner. Rapamycin, an inhibitor of mechanistic target of rapamycin (mTOR) signaling, diminished insulin's effects and increase taste cell generation. Altogether, circulating insulin might be an important regulator of taste cell growth and/or proliferation via activation of the mTOR pathway.
胰岛素及其受体（IR）在啮齿动物味细胞中的表达已被提出，但确切哪些类型的味细胞表达 IR 以及胰岛素信号在味器官中的功能仍有待确定。在这项研究中，我们使用 RT-PCR、免疫组织化学和定量 PCR 分析了体内小鼠味芽细胞中 IR mRNA 和蛋白的表达，并在类器官中探索了其功能。在小鼠味觉组织中，IR 在味觉芽中广泛表达，包括 II 型和 III 型味细胞。使用 3-D 味芽类器官，我们发现培养基中的胰岛素显著减少了味细胞的数量，并以浓度依赖性方式降低了许多味细胞基因的 mRNA 表达水平，包括核苷酸三磷酸二磷酸水解酶-2（NTPDase2）、Tas1R3（T1R3）、gustducin、碳酸酐酶 4（CA4）、葡萄糖转运蛋白-8（GLUT8）和钠-葡萄糖协同转运蛋白-1（SGLT1）。雷帕霉素是机械性靶标雷帕霉素（mTOR）信号的抑制剂，可减弱胰岛素的作用并增加味细胞的生成。总之，循环胰岛素可能通过激活 mTOR 途径成为调节味细胞生长和/或增殖的重要调节剂。
