In mammals, taste buds typically contain 50–100 tightly packed taste-receptor cells (TRCs), representing all five basic qualities: sweet, sour, bitter, salty and umami. Notably, mature taste cells have life spans of only 5–20 days and, consequently, are constantly replenished by differentiation of taste stem cells. Given the importance of establishing and maintaining appropriate connectivity between TRCs and their partner ganglion neurons (that is, ensuring that a labelled line from sweet TRCs connects to sweet neurons, bitter TRCs to bitter neurons, sour to sour, and so on), we examined how new connections are specified to retain fidelity of signal transmission. Here we show that bitter and sweet TRCs provide instructive signals to bitter and sweet target neurons via different guidance molecules (SEMA3A and SEMA7A). We demonstrate that targeted expression of SEMA3A or SEMA7A in different classes of TRCs produces peripheral taste systems with miswired sweet or bitter cells. Indeed, we engineered mice with bitter neurons that now responded to sweet tastants, sweet neurons that responded to bitter or sweet neurons responding to sour stimuli. Together, these results uncover the basic logic of the wiring of the taste system at the periphery, and illustrate how a labelled-line sensory circuit preserves signalling integrity despite rapid and stochastic turnover of receptor cells.

中文翻译：

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重新连接味觉系统

在哺乳动物中，味蕾通常包含 50-100 个紧密排列的味觉受体细胞 (TRC)，代表所有五种基本品质：甜、酸、苦、咸和鲜味。值得注意的是，成熟的味觉细胞只有 5-20 天的寿命，因此，味觉干细胞的分化不断补充。鉴于在 TRC 与其伙伴神经节神经元之间建立和维持适当连接的重要性（即，确保从甜 TRC 连接到甜神经元、苦 TRC 到苦神经元、酸到酸等的标记线），我们检查了如何指定新连接以保持信号传输的保真度。在这里，我们表明苦味和甜味 TRC 通过不同的引导分子（SEMA3A 和 SEMA7A）向苦味和甜味目标神经元提供指导信号。我们证明了 SEMA3A 或 SEMA7A 在不同类别的 TRC 中的靶向表达会产生带有错误连接的甜味或苦味细胞的外围味觉系统。事实上，我们设计了具有苦味神经元的小鼠，这些神经元现在对甜味剂有反应，甜味神经元对苦味或甜味神经元对酸味刺激有反应。总之，这些结果揭示了外围味觉系统布线的基本逻辑，并说明了标记线感觉电路如何在受体细胞快速和随机更新的情况下保持信号完整性。对酸味刺激有反应的甜味神经元或对酸味刺激有反应的甜味神经元。总之，这些结果揭示了外围味觉系统布线的基本逻辑，并说明了标记线感觉电路如何在受体细胞快速和随机更新的情况下保持信号完整性。对酸味刺激有反应的甜味神经元或对酸味刺激有反应的甜味神经元。总之，这些结果揭示了外围味觉系统布线的基本逻辑，并说明了标记线感觉电路如何在受体细胞快速和随机更新的情况下保持信号完整性。