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Induction mechanism and physiological role of autophagy in yeast and plant cell.

酵母和植物细胞自噬的诱导机制和生理作用。

基本信息

批准号：
02454009
负责人：
OHSUMI Yoshinori
金额：
$ 1.47万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-02454009/
关键词：
Yeast autophagy vacuole acidic compartment protein turnover cell cycle 自食胞

项目摘要

It was first shown that yeast, Saccharomyces cerevisiae, shows extensive autophagic activity. It provides a good model system for understanding autophagy at molecular level. Summary of research in these two years are follows. (1) By using vacuolar proteinases-deficient mutants autophagy was demonstrated with light microscope ; under various nutrient-defifient conditions spherical bodies containing cytosolic components, named autophagic bodies, accumulated in the vacuoles within 3-4 hours. (2) Dynamic behavior of intracellular membranes in the cell under nutrientdeficient condition was investigated by electron microscope using rapidfreezing and freeze-substitution methods. Then we proposed a model for autophagy in yeast cells. (3) By using mutants of cAMP-signal pathway cAMP was shown to be a negative regulator of autophagic process in yeast. (4) Mutants of vacuolar membrane proton ATPase still accumulated autophagic bodies under nutrient starvation into their vacuoles. It was concluded that in contrast to animal cell acidification of vacuole (lysosome) was not essential to autophagy in yeast. (5) Vacuolar proteinase B was shown to be the most responsible enzymes to degrade the autophagic bodies in the vacuoles by biochemical and molecular genetical analyses. (6) Under nitrogen starvation condition wild type cell proceed its cell cycle to Gl. However, vacuolar proteinase-deficient cells or mutants cell activated CAMP pathway failed to arrest to G1 and rapidly lost their viability. It was suggested that bulk turnover of proteins by autophagy is obligatory to provide amino acids to proceed their cell cycle. (7) Mutants difective with autophagic process were isolated under light microscope. Various genes involved in the whole process of autophagy may be identified.

首次发现酿酒酵母具有广泛的自噬活性。这为在分子水平上理解自噬提供了一个很好的模型系统。以下是这两年的研究总结。(1)利用空泡蛋白水解酶缺失突变体，在光镜下观察到自噬现象，在不同营养条件下，含有胞液成分的球形小体在3-4小时内聚集在空泡中，称为自噬小体。(2)采用快速冷冻法和冷冻替换法，在电子显微镜下观察了营养缺乏条件下细胞内膜的动态行为。然后，我们提出了酵母细胞自噬的模型。(3)利用cAMP信号通路突变体，证明cAMP是酵母自噬过程的负调控因子。(4)液泡膜质子ATPase突变体在营养饥饿条件下仍可积累自噬小体进入液泡。与动物细胞不同，液泡(溶酶体)的酸化不是酵母自噬所必需的。(5)生化和分子遗传学分析表明，液泡酶B是降解液泡中自噬小体的最主要酶。(6)在氮饥饿条件下，野生型细胞进入G1期。然而，空泡蛋白水解酶缺陷细胞或突变细胞激活的cAMP通路未能阻止其进入G1期，并迅速丧失其活性。有人认为，蛋白质通过自噬的大量周转是必需的，以提供氨基酸来继续其细胞周期。(7)光镜下分离出具有自噬功能的突变株。参与自噬整个过程的各种基因可能会被识别出来。