Molecular Mechanism and Signal Transduction for Salivary Secretion

本研究的目的是探讨唾液分泌的分子机制，即通过信号转导，唾液蛋白的合成、分选、分泌颗粒的胞内转运和胞吐时的膜融合等一系列现象来表明唾液分泌的分子机制。缝隙连接是由连接蛋白组成的，具有调节唾液分泌的信号功能。众所周知，不同类型的连接蛋白存在于各种组织和器官中。通过免疫印迹、免疫组织化学和免疫细胞化学的方法，我们证实了连接蛋白26和32都位于腺泡细胞之间，而连接蛋白43则分布在唾液腺肌上皮细胞之间。这些可能表明连接蛋白26和32都参与腺泡细胞中唾液分泌的信号转导，但连接蛋白43与肌上皮细胞收缩的信号转导相关（J Histochem Cytochem 44：49- 56，1996; EuropJ Morphol 34： 关于我们 197- 202，1996）。我们还阐明了连接蛋白26和32在唾液腺中构成相同的间隙连接（Acta Histochem Cytochem，出版中）。采用PCR、原位杂交和免疫组织化学研究了连接蛋白32和43在发育中的唾液腺中的表达（EuropJ Morphol，出版中）。我们不仅研究了肌动蛋白丝和蛋白质组成的紧密连接，如ZO-1或occludin的定位，但网格蛋白参与内吞和膜融合相关蛋白（突触素）在腺泡细胞分泌过程中的表达，免疫组织化学，免疫细胞化学和共聚焦激光扫描显微镜。肌动蛋白丝的定位与ZO-1和Occludin密切相关。在IPR刺激后10或30分钟，网格蛋白位于细胞内小管的外围。这可能表明分泌颗粒膜的内吞作用在分泌后立即发生（手稿，准备中）。少

The purpose of this study is to investigate the molecular mechanism of salivary secretion, which is indicated by serial phenomena including synthesis of salivary protein, sorting, intracellular transport of secretory granules and membrane fusion at the exocytosis through the signal transduction. Gap junctions which possess a signal function for salivary secretion are composed of proteins termed as connexins. It is well known that different types of connexins exist in various tissues and organs. Using western blotting, immunohistochemistry and immunocytochemistry, we demonstrated that both connexins 26 and 32 were Iocated between acinar cells, but connexin 43 was distributed between myoepithelial cells in the salivary glands. These may suggest that both connexins 26 and 32 participate in signal transduction for salivary secretion in acinar cells, but connexin 43 is correlated to signaling for contraction of myoepithelial cells (J Histochem Cytochem 44 : 49-56,1996 ; Europ J Morphol 34 : … More 197-202,1996). We also clarified that connexins 26 and 32 constituted the same gap junction in the salivary gland (Acta Histochem Cytochem, in press). The expression of connexins 32 and 43 was investigated in the developing salivary glands employing PCR,in situ hybridization and immunohistochemistry (Europ J Morphol, in press). We studied not only the localization of actin filaments and proteins constituting tight junction such as ZO-1 or occludin but also the expression of clathlin participating endocytosis and a membrane-fusion associated protein (synaptophysin) in acinar cells during secretion using immunohistochemistry, immunocytochemistry and confocal laser scanning microscope. There was a close relationship between the localization of actin filaments and ZO-1 or Occludin. Clathrin was located at the periphery of the intracellular canalicula 10 or 30 minutes after IPR stimulation. This may indicate that endocytosis of secretory-granule-membrane occur immediately after the secretion (manuscript, in preparation). Less