Paine R, Ben-Ze'ev A, Farmer S R, Brody J S
Pulmonary Center, Boston University School of Medicine, Massachusetts 02118.
Dev Biol. 1988 Oct;129(2):505-15. doi: 10.1016/0012-1606(88)90396-x.
During the last stages of fetal life, the immature epithelial cells of the rat lung alveolus develop the properties of mature type 2 cells. Adult type 2 cells rapidly lose these same properties when isolated and maintained in cell culture. We have examined the synthesis of cytokeratin proteins by adult type 2 cells as they lose their differentiated characteristics during 1 week in culture, and of immature fetal alveolar epithelial cells as they differentiate either in utero or when cultured on an extracellular matrix. Freshly isolated adult type 2 cells synthesize four cytokeratins which by electrophoretic mobilities and Western blot analysis correspond to human cytokeratins Nos. 7, 8, 18, and 19. During 7 days in culture synthesis of cytokeratin No. 19 is dramatically decreased and cytokeratin No. 18 becomes the predominant acidic cytokeratin produced. Fetal lung epithelial cells at 18 days gestation lack most characteristics of mature type 2 cells. When freshly isolated, these cells synthesize cytokeratins Nos. 7, 8, and 18 but make only minimal amounts of cytokeratin No. 19. When these cells are allowed to mature either in utero or in culture on a whole basement membrane extract, they develop both the morphological characteristics and the pattern of cytokeratin synthesis of fully developed type 2 cells, with cytokeratins No. 19 being the major acidic cytokeratin produced.
在胎儿期的最后阶段，大鼠肺泡的未成熟上皮细胞逐渐具备成熟Ⅱ型细胞的特性。成年Ⅱ型细胞在分离并进行细胞培养时，会迅速丧失这些相同的特性。我们研究了成年Ⅱ型细胞在培养1周期间丧失其分化特征时细胞角蛋白的合成情况，以及未成熟胎儿肺泡上皮细胞在子宫内或在细胞外基质上培养时分化过程中的细胞角蛋白合成情况。刚分离的成年Ⅱ型细胞合成四种细胞角蛋白，通过电泳迁移率和蛋白质印迹分析，它们分别对应于人细胞角蛋白7、8、18和19。在培养7天的过程中，细胞角蛋白19的合成显著减少，细胞角蛋白18成为产生的主要酸性细胞角蛋白。妊娠18天的胎儿肺上皮细胞缺乏成熟Ⅱ型细胞的大多数特征。刚分离时，这些细胞合成细胞角蛋白7、8和18，但仅产生极少量的细胞角蛋白19。当这些细胞在子宫内或在完整基底膜提取物上培养使其成熟时，它们会呈现出完全发育的Ⅱ型细胞的形态特征和细胞角蛋白合成模式，其中细胞角蛋白19是产生的主要酸性细胞角蛋白。
