Guttman S D, Gorovsky M A
Cell. 1979 Jun;17(2):307-17. doi: 10.1016/0092-8674(79)90156-9.
Deciliated starved Tetrahymena recover motility with kinetics similar to those of growing cells and, like growing cells, require RNA and protein synthesis for regeneration. Comparisons of polysome profiles and electrophoretic analyses of newly synthesized proteins indicate, however, that the basal level of protein synthesis in starved cells is markedly lower than that in growing cells. This difference allows demonstration of changes in protein synthesis following deciliation of starved cells which cannot be detected (if they occur at all) in growing cells. Deciliation of starved cells induces a specific and orderly program of protein synthesis. The synthesis of an 80,000 dalton protein (deciliation-induced protein, DIP) begins shortly after deciliation, comprises 15% of the protein synthesized from 20-60 min, and declines around 60 min after deciliation, shortly after most cells have begun to regenerate cilia. The synthesis of a 55,000 dalton protein is also induced during regeneration and has been identified as tubulin using a well characterized antibody made to ciliary tubulin. Tubulin synthesis is undetectable during the first hour after deciliation even though 60-80% of the cells regain mobility and regenerate short but clearly visible cilia. Tubulin synthesis begins 60 min after deciliation and continues for 2 hr. At its peak, tubulin comprises 7-8% of the protein synthesized. The results of actinomycin D addition at different times after deciliation suggest that RNA required for DIP synthesis is synthesized early (0-30 min), while RNA required for tubulin is synthesized later and over a longer period (30-90 min). Thus deciliation of starved cells, an event occurring at the cell periphery, initiates a well defined and reproducible series of events culminating in cilia formation. This system should be useful in elucidating the molecular mechanisms regulating gene expression and organelle biogenesis in Tetrahymena.
脱纤毛饥饿的四膜虫恢复运动的动力学与生长细胞相似，并且与生长细胞一样，再生需要RNA和蛋白质合成。然而，多核糖体谱的比较和新合成蛋白质的电泳分析表明，饥饿细胞中蛋白质合成的基础水平明显低于生长细胞。这种差异使得能够证明饥饿细胞脱纤毛后蛋白质合成的变化，而在生长细胞中（如果这些变化确实发生）则无法检测到。饥饿细胞的脱纤毛诱导了一个特定且有序的蛋白质合成程序。一种80,000道尔顿蛋白质（脱纤毛诱导蛋白，DIP）的合成在脱纤毛后不久开始，占20 - 60分钟内合成蛋白质的15%，并在脱纤毛后约60分钟下降，此时大多数细胞已开始再生纤毛。一种55,000道尔顿蛋白质的合成在再生过程中也被诱导，并且使用针对纤毛微管蛋白制备的特征明确的抗体已将其鉴定为微管蛋白。即使60 - 80%的细胞恢复运动并再生出短但清晰可见的纤毛，脱纤毛后第一小时内微管蛋白的合成仍无法检测到。微管蛋白合成在脱纤毛后60分钟开始并持续2小时。在其峰值时，微管蛋白占合成蛋白质的7 - 8%。脱纤毛后不同时间添加放线菌素D的结果表明，DIP合成所需的RNA在早期（0 - 30分钟）合成，而微管蛋白所需的RNA在后期且在更长时间段（30 - 90分钟）合成。因此，饥饿细胞的脱纤毛，这一发生在细胞周边的事件，引发了一系列明确且可重复的事件，最终导致纤毛形成。该系统应有助于阐明调节四膜虫基因表达和细胞器生物发生的分子机制。
