Michlig Stéphanie, Damak Sami, Le Coutre Johannes
Nestlé Research Center, Vers-chez-les-Blanc, Lausanne 1000, Switzerland.
J Comp Neurol. 2007 Jun 20;502(6):1003-11. doi: 10.1002/cne.21354.
Tight junctions operate as semipermeable barriers in epithelial tissue, separating the apical from the basolateral sides of the cells. Membrane proteins of the claudin family represent the major tight junction constituents, and some reinforce permeability barriers, whereas others create pores based on solute size and ion selectivity. To outline paracellular permeability pathways in gustatory tissue, all claudins expressed in mouse taste buds and in human fungiform papillae have been characterized. Twelve claudins are expressed in murine taste-papillae-enriched tissue, and five of those are expressed in human fungiform papillae. A subset of the claudins expressed in mouse papillae is uniquely found in taste buds. By immunohistochemistry, claudin 4 has been found in mouse taste epithelium, with high abundance around the taste pore. Claudin 6 is explicitly detected inside the pore, claudin 7 was found at the basolateral side of taste cells, and claudin 8 was found around the pore. With the ion permeability features of the different claudins, a highly specific permeability pattern for paracellular diffusion is apparent, which indicates a peripheral mechanism for taste coding.
紧密连接在上皮组织中作为半透性屏障发挥作用，将细胞的顶端与基底外侧分隔开。紧密连接蛋白家族的膜蛋白是紧密连接的主要组成成分，其中一些增强渗透屏障，而另一些则根据溶质大小和离子选择性形成孔隙。为了勾勒味觉组织中的细胞旁通透性途径，已对在小鼠味蕾和人菌状乳头中表达的所有紧密连接蛋白进行了表征。在富含小鼠味乳头的组织中表达了12种紧密连接蛋白，其中5种在人菌状乳头中表达。在小鼠乳头中表达的紧密连接蛋白的一个亚群在味蕾中独特存在。通过免疫组织化学，在小鼠味觉上皮中发现了紧密连接蛋白4，在味孔周围含量很高。在孔内明确检测到紧密连接蛋白6，在味觉细胞的基底外侧发现了紧密连接蛋白7，在孔周围发现了紧密连接蛋白8。鉴于不同紧密连接蛋白的离子通透性特征，细胞旁扩散的高度特异性通透性模式显而易见，这表明了一种味觉编码的外周机制。
