Kubohara Y, Maeda M, Okamoto K
Department of Botany, Faculty of Science, Kyoto University, Japan.
Exp Cell Res. 1993 Jul;207(1):107-14. doi: 10.1006/excr.1993.1168.
The requirements for the terminal differentiation process of the stalk pathway (from prestalk to stalk) of Dictyostelium discoideum were analyzed by using a low-cell-density culture system with prestalk cells isolated from normally developed slugs. Any of the substances, such as differentiation-inducing factor-1 (DIF-1), DIF-2, dimethyloxazolidinedione, and adenosine, that had been shown to promote prestalk/stalk differentiation did not cause an efficient and consistent induction of prestalk-to-stalk conversion, either alone or in combination. However, the addition of 8-bromoadenosine 3',5'-cyclic monophosphate (Br-cAMP) resulted in high efficiency (80-90%) of stalk cell formation which accompanied the accumulation of a stalk-specific protein, wst34. The maturation process was inhibited by Ca2+ but not by Mg2+. More importantly, the Br-cAMP-induced stalk cell differentiation was neither inhibited nor promoted by DIF-1, cAMP, or ammonia and occurred even at very low cell densities if only Br-cAMP was supplied. Since Br-cAMP is though to penetrate into the cells and to activate the intracellular protein kinase A, the present results suggest that the activation of protein kinase A is sufficient for prestalk-to-stalk conversion.
通过使用从正常发育的蛞蝓中分离出的前柄细胞的低细胞密度培养系统，分析了盘基网柄菌柄细胞分化途径（从前柄细胞到柄细胞）的终末分化过程的要求。任何已被证明能促进前柄/柄细胞分化的物质，如分化诱导因子-1（DIF-1）、DIF-2、二甲基恶唑烷二酮和腺苷，单独或组合使用时，均不能有效且一致地诱导前柄细胞向柄细胞的转化。然而，添加8-溴腺苷3',5'-环磷酸（Br-cAMP）可导致高效（80-90%）的柄细胞形成，并伴随着一种柄特异性蛋白wst34的积累。成熟过程受到Ca2+的抑制，但不受Mg2+的抑制。更重要的是，Br-cAMP诱导的柄细胞分化既不受DIF-1、cAMP或氨的抑制，也不受其促进，并且即使在细胞密度非常低的情况下，如果仅提供Br-cAMP，分化也会发生。由于Br-cAMP被认为可穿透细胞并激活细胞内蛋白激酶A，目前的结果表明蛋白激酶A的激活足以实现前柄细胞向柄细胞的转化。
