Taub M L, Syracuse J A, Cai J W, Fiorella P, Subjeck J R
Department of Biochemistry, State University of New York, Buffalo 14214.
Exp Cell Res. 1989 May;182(1):105-13. doi: 10.1016/0014-4827(89)90283-8.
Madin-Darby canine kidney (MDCK) cells spontaneously form dome-like structures in vitro, a phenomenon which has been proposed to be indicative of cellular differentiation. This study indicates the existence of a correlation between the induction of domes and of glucose-regulated proteins during glucose starvation. When MDCK monolayers were glucose deprived, domes appeared very rapidly. After only 3 h of glucose deprivation domes appeared in 69% of the microscope fields. The level of expression of glucose-regulated proteins (grps) as well as domes was examined over a 6-h time interval of glucose deprivation. Both grp 76 and 97 were induced over this time interval, with grp 76 being the more readily detectable. The level of induction of grp 76 as a function of time was quantitated by means of densitometry measurements. The induction of domes was examined in parallel with the induction of grp 76. The results indicated that the induction of grp 76 and domes occurs with a similar time course. The effect of glucose deprivation on the initial rate of ouabain-sensitive Rb+ uptake was also examined. Within the first 4 h of glucose deprivation, the initial rate of ouabain-sensitive Rb+ uptake did not differ significantly in glucose-deprived and control MDCK monolayers. These observations indicate that unlike the case with other methods of dome induction (e.g., treatment with either prostaglandin E1 (PGE1) or hexamethylene bis-acetamide (HMBA] glucose deprivation does not affect the Na+K+ ATPase activity of MDCK monolayers. These observations suggest that PGE1, HMBA, and glucose deprivation affect dome formation in MDCK monolayers by means of distinct mechanisms.
麦迪逊-达比犬肾（MDCK）细胞在体外能自发形成穹顶状结构，这一现象被认为是细胞分化的标志。本研究表明，在葡萄糖饥饿期间，穹顶的诱导与葡萄糖调节蛋白的诱导之间存在相关性。当MDCK单层细胞被剥夺葡萄糖时，穹顶很快就会出现。仅在葡萄糖剥夺3小时后，69%的显微镜视野中就出现了穹顶。在葡萄糖剥夺的6小时时间间隔内，检测了葡萄糖调节蛋白（grps）的表达水平以及穹顶的情况。在这段时间间隔内，grp 76和97均被诱导，其中grp 76更容易被检测到。通过光密度测量法定量了grp 76随时间的诱导水平。同时检测了穹顶的诱导情况与grp 76的诱导情况。结果表明，grp 76和穹顶的诱导具有相似的时间进程。还研究了葡萄糖剥夺对哇巴因敏感的Rb+摄取初始速率的影响。在葡萄糖剥夺的前4小时内，葡萄糖剥夺组和对照MDCK单层细胞中哇巴因敏感的Rb+摄取初始速率没有显著差异。这些观察结果表明，与其他诱导穹顶的方法（如用前列腺素E1（PGE1）或六甲撑双乙酰胺（HMBA）处理）不同，葡萄糖剥夺不会影响MDCK单层细胞的Na+K+ ATP酶活性。这些观察结果表明，PGE1、HMBA和葡萄糖剥夺通过不同的机制影响MDCK单层细胞中穹顶的形成。
