Salger K, Wetterauer B W
Zoologisches Institut, Ludwig-Maximilians-Universität of München, Luisenstrasse 14, D-80333 München, Germany.
Differentiation. 2000 Dec;66(4-5):197-207. doi: 10.1046/j.1432-0436.2000.660406.x.
Growth and development are mutually exclusive in Dictyostelium discoideum. The transition between the two stages of the life cycle is regulated by the relative abundance of nutrients and proteins secreted by the cells which reflect population density. At the transition from growth to development, the discoidin genes--developmental markers--are induced by the "quorum" protein PSF. The effect of PSF is counteracted by food bacteria and by folate [8]. We show that folate treatment during growth delays morphologic development. Furthermore, we demonstrate that in a mutant of Dictyostelium discoideum (V188, renamed HBW3), which expresses discoidinI during growth and which develops rapidly [46], discoidinI expression is less sensitive to folate than in wild type cells. Finally, we present evidence that fragments of the discoidinI gamma promoter which are unresponsive to PSF and CM are sufficient for misregulation in the mutant. The only known regulator of these promoter elements is folate. Changes in the expression of other early developmental genes are also shown. Taken together, these data suggest that the reduced sensitivity to folate might be the cause for the "rapid development" phenotype of the mutant and that folate regulates developmental timing.
在盘基网柄菌中，生长和发育是相互排斥的。生命周期两个阶段之间的转变由细胞分泌的反映群体密度的营养物质和蛋白质的相对丰度来调节。在从生长向发育转变时，盘状菌素基因（发育标志物）由“群体感应”蛋白PSF诱导。PSF的作用会被食物细菌和叶酸抵消[8]。我们发现生长期间的叶酸处理会延迟形态发育。此外，我们证明在盘基网柄菌的一个突变体（V188，重命名为HBW3）中，该突变体在生长期间表达盘状菌素I且发育迅速[46]，其盘状菌素I的表达对叶酸的敏感性低于野生型细胞。最后，我们提供证据表明盘状菌素Iγ启动子中对PSF和CM无反应的片段足以导致该突变体的调控异常。这些启动子元件唯一已知的调节因子是叶酸。还展示了其他早期发育基因表达的变化。综上所述，这些数据表明对叶酸敏感性降低可能是该突变体“快速发育”表型的原因，并且叶酸调节发育时间。
