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Molecular mechanisms of salivary exocytosis-endocytosis coupling

唾液胞吐-内吞耦合的分子机制

基本信息

批准号：
09671866
负责人：
SEGAWA Akihisa
金额：
$ 1.98万
依托单位：
Kitasato University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09671866/
关键词：
Salivary glands exocytosis endocytosis calcium IPィイD23ィエD2 receptor

项目摘要

This research project is aimed to clarify the molecular mechanisms involved in exocytosis-endocytosis coupling in salivary glands by morphological/functional/biochemical approaches. This year, analyses were performed on whole gland perfusion system, calcium signaling and parotid glands in l3-galactosidase knock-out mice.1) Whole gland perfusion: Isolated whole parotid glands of rats were perfused arterially with isoproterenol (β-agonist) or carbachol (muscarinic agonist), and secreted saliva and tissues were collected sequentially; β-stimulation evoked exocytosis following which the fused granule membranes were removed one by one. Muscarinic stimulation inhibited this removal process. Since muscarinic stimulation causes fluid secretion but β-stimulation does not, it is suggested that membrane retrieval process plays significant roles in regulation of fluid secretion.2) Calcium signaling: High speed cofocal microscopy of living parotid glands showed the synchronized response in acini and the non-synchronized response in ducts. Gap junction was detected between acinar cells but not duct cells. Acini are likely to function as a syncitium.3) β-galactosidase knock-out mice: β-galactosidase is involved in the lysosomal degradation of membrane components. Parotid acinar cells in mice deficient in this enzyme revealed vacuolar profiles in the cytoplasm. Electron microscopic observation demonstrated that the vacuoles appeared in the RER region. Unexpectedly, this enzyme is suggested to play roles in the biosynthetic processes rather than the degradation.

本研究旨在通过形态学、功能学和生物化学方法阐明唾液腺胞吐-胞吞耦合的分子机制。今年，我们对β-半乳糖苷酶基因敲除小鼠的全腺体灌注系统、钙信号和腮腺进行了分析。1）全腺体灌注：用异丙肾上腺素动脉灌注大鼠的离体全腮腺（β-激动剂）或卡巴胆碱（毒蕈碱激动剂），并依次收集分泌的唾液和组织; β刺激诱发胞吐作用，随后融合的颗粒膜被逐一去除。毒蕈碱刺激抑制了这一清除过程。由于毒蕈碱刺激引起液体分泌，而β-刺激不引起液体分泌，因此推测膜修复过程在液体分泌的调节中起重要作用。2）钙信号：在活体腮腺的高速共聚焦显微镜下观察到腺泡的同步反应和导管的非同步反应。腺泡细胞间有缝隙连接，导管细胞间无缝隙连接。腺泡可能具有合胞体的功能。3）β-半乳糖苷酶基因敲除小鼠：β-半乳糖苷酶参与溶酶体降解膜成分。这种酶缺乏的小鼠腮腺腺泡细胞在细胞质中呈现空泡状。电镜观察表明，粗面内质网区出现空泡。出乎意料的是，这种酶被认为在生物合成过程中发挥作用，而不是降解。