盘基网柄菌细胞分化和凋亡中酸性磷酸酶的定位

Localization of acid phophatase in Dictyostelium discoideum cells during differentiation and apoptosis

利用电镜酶细胞化学方法,观察盘基网柄菌细胞分化和凋亡过程中酸性磷酸酶的变化。在细胞丘阶段,酶反应颗粒出现在线粒体内自噬空泡内,随着内自噬空泡的逐渐增大,线粒体内的酶反应颗粒逐渐增多,线粒体内嵴结构不断破坏,直至遍布整个空泡化的线粒体内;当细胞发育至前孢子细胞时,由于嵴结构被完全破坏,酶反应颗粒主要集中在前孢子细胞空泡的单层膜上,空泡化的线粒体内酶反应颗粒逐渐消失。在凋亡的柄细胞中,自噬泡内酶反应强烈,凋亡中期的前柄细胞的细胞核中出现酶反应颗粒,均匀分布在细胞核中,直至细胞核与自噬泡融合。在孢子细胞外被与质膜间也观察到非溶酶体酸性磷酸酶。所得结果证实:线粒体内自噬小泡具有消化功能;自噬泡内酶活性与细胞器消亡有关;细胞核中的酸性磷酸酶可能作为一种非溶酶体酸性磷酸酶参与细胞核中核蛋白的脱磷酸化过程。

By means of the electron microscopic enzymo-cytochemistry, the process of acid phosphatase activity during in Dictyostelium discoideum cells during differentiation and apoptosis was investigated. The enzyme activity was localized within the small vacuoles nearby the outer membrane of some mitochondria at mound stage during Dictyostelium discoideum development. At the same time that the small vacuoles became bigger and bigger, the acid phosphatase activity was increased until the all vacuolated mitochondria were covered with the particles of the acid phosphatase. In prespore cell at slug stage, when the cristea had been eliminated completely, the acid phosphatase activity was restricted to the monomembrane of the vacuolated mitochondrion. The activity of acid phosphataso was very high in the autophage vacuole of the prestalk cells. The acid phosphatase was found in the nucleus of prestalk cells, dispersed evenly in the karyoplasm and disappeared until nucleus was engulfed by autophagic vacuoles. Non-lysosomal acid phosphatase was observed between the spore coat and spore membrane. The acid phosphataso acitivity of autophagy in mitochondrion provides the further evidence for the criterion charactering the apoptosis at the level of organelle. The acid phosphatase in nucleus, considered as an non-lysosomal enzyme, appears to be involved in the dephosphorylation of nucleoprotein. This result suggests that it is associated with the regulation of gene expression relating to apoptosis or cell differentiation .