Finney R, Ellis M, Langtimm C, Rosen E, Firtel R, Soll D R
Dev Biol. 1987 Apr;120(2):561-76. doi: 10.1016/0012-1606(87)90259-4.
During development of Dictyostelium discoideum, cells acquire the capacity to rapidly recapitulate morphogenesis. Therefore, when cells at the loose aggregate stage are disaggregated and challenged to reaggregate, they do so in a tenth of the original time. If loose aggregate cells are disaggregated and resuspended in buffered dextrose solution (erasure medium), they retain the capacity of rapid recapitulation for 80 min, then completely lose this capacity in a single, synchronous step referred to as the "erasure event." The erasure event sets in motion a program of dedifferentiation during which cells lose developmentally acquired characteristics at different times. The erasure event is inhibited by the addition of 10(-4) M cAMP to erasure medium. The synthesis of 33 growth-associated polypeptides, the synthesis of 53 development-associated polypeptides, and the level of 2 development-associated RNAs have been monitored during the erasure program and in cultures inhibited from erasing by the addition of 10(-4) M cAMP. Growth-associated polypeptides begin to be resynthesized and development-associated polypeptides exhibit dramatic decreases in rate of synthesis at different times throughout the first 240 min in erasure medium. Inhibiting the erasure event with cAMP has no major effect in the resynthesis of the majority of growth-associated polypeptides. Only one growth-associated polypeptide, V28, is completely inhibited by cAMP, suggesting that it may play a role in the erasure process. In contrast, inhibiting the erasure event with cAMP has a marked effect on the synthesis of development-associated polypeptides, causing a dramatic reduction in the rate at which synthesis decreases for 6 polypeptides, and completely inhibits the decrease in the synthetic rate of 8 polypeptides. The two development-associated RNAs, 16G1 and 10C3, exhibit two distinctly different patterns of loss during erasure, but in both cases cAMP added at time zero of the erasure process dramatically retards or inhibits loss. In addition, when cAMP is added just prior to the erasure event, it inhibits the erasure event and stimulates a rapid increase in the level of 16G1 RNA back to the developmental level. The level of 16G1 RNA then remains at this level for at least 400 min. When cAMP is added after the erasure event, it causes a low, transient increase in the level of 16G1 RNA. These results are considered both in relation to the program of erasure, and in relation to the role of cAMP in the expression of developmental genes during the forward program of development.
在盘基网柄菌的发育过程中，细胞获得了快速重演形态发生的能力。因此，当处于松散聚集体阶段的细胞被分散并再次受到聚集挑战时，它们能在原来十分之一的时间内完成聚集。如果将松散聚集体细胞分散并重悬于缓冲葡萄糖溶液（消除培养基）中，它们在80分钟内仍保持快速重演的能力，然后在一个被称为“消除事件”的单一同步步骤中完全丧失这种能力。消除事件启动了一个去分化程序，在此过程中细胞在不同时间失去发育过程中获得的特征。向消除培养基中添加10⁻⁴ M的环磷酸腺苷（cAMP）可抑制消除事件。在消除程序期间以及在添加10⁻⁴ M cAMP而被抑制消除的培养物中，监测了33种与生长相关的多肽的合成、53种与发育相关的多肽的合成以及2种与发育相关的RNA的水平。在消除培养基中的前240分钟内，与生长相关的多肽开始重新合成，与发育相关的多肽在不同时间合成速率显著下降。用cAMP抑制消除事件对大多数与生长相关多肽的重新合成没有重大影响。只有一种与生长相关的多肽V28被cAMP完全抑制，这表明它可能在消除过程中起作用。相反，用cAMP抑制消除事件对与发育相关多肽的合成有显著影响，导致6种多肽合成速率下降的速度急剧降低，并完全抑制了8种多肽合成速率的下降。两种与发育相关的RNA，16G1和10C3，在消除过程中呈现出两种明显不同的丧失模式，但在这两种情况下，在消除过程开始时添加cAMP会显著延缓或抑制丧失。此外，在消除事件即将发生之前添加cAMP，它会抑制消除事件并刺激16G1 RNA水平迅速回升至发育水平。然后16G1 RNA水平至少在400分钟内保持在该水平。在消除事件之后添加cAMP，它会导致16G1 RNA水平出现低水平的短暂升高。这些结果既与消除程序有关，也与cAMP在正向发育程序中发育基因表达中的作用有关。
