Maeda Mineko, Sakamoto Haruyo, Iranfar Negin, Fuller Danny, Maruo Toshinari, Ogihara Satoshi, Morio Takahiro, Urushihara Hideko, Tanaka Yoshimasa, Loomis William F
Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.
Eukaryot Cell. 2003 Jun;2(3):627-37. doi: 10.1128/EC.2.3.627-637.2003.
We used microarrays carrying most of the genes that are developmentally regulated in Dictyostelium to discover those that are preferentially expressed in prestalk cells. Prestalk cells are localized at the front of slugs and play crucial roles in morphogenesis and slug migration. Using whole-mount in situ hybridization, we were able to verify 104 prestalk genes. Three of these were found to be expressed only in cells at the very front of slugs, the PstA cell type. Another 10 genes were found to be expressed in the small number of cells that form a central core at the anterior, the PstAB cell type. The rest of the prestalk-specific genes are expressed in PstO cells, which are found immediately posterior to PstA cells but anterior to 80% of the slug that consists of prespore cells. Half of these are also expressed in PstA cells. At later stages of development, the patterns of expression of a considerable number of these prestalk genes changes significantly, allowing us to further subdivide them. Some are expressed at much higher levels during culmination, while others are repressed. These results demonstrate the extremely dynamic nature of cell-type-specific expression in Dictyostelium and further define the changing physiology of the cell types. One of the signals that affect gene expression in PstO cells is the hexaphenone DIF-1. We found that expression of about half of the PstO-specific genes were affected in a mutant that is unable to synthesize DIF-1, while the rest appeared to be DIF independent. These results indicate that differentiation of some aspects of PstO cells can occur in the absence of DIF-1.
我们使用了携带大多数在盘基网柄菌发育过程中受调控基因的微阵列，来发现那些在前柄细胞中优先表达的基因。前柄细胞位于蛞蝓状群体的前端，在形态发生和蛞蝓状群体迁移中发挥关键作用。通过全组织原位杂交，我们能够验证104个前柄基因。其中三个被发现仅在蛞蝓状群体最前端的细胞（PstA细胞类型）中表达。另外10个基因被发现在前体形成中央核心的少数细胞（PstAB细胞类型）中表达。其余的前柄特异性基因在PstO细胞中表达，PstO细胞紧邻PstA细胞后方，但在由前孢子细胞组成的蛞蝓状群体的80%之前。其中一半也在PstA细胞中表达。在发育后期，相当数量的这些前柄基因的表达模式发生了显著变化，这使我们能够进一步细分它们。一些在发育后期表达水平大幅提高，而另一些则受到抑制。这些结果证明了盘基网柄菌中细胞类型特异性表达的极端动态性质，并进一步定义了细胞类型不断变化的生理学特征。影响PstO细胞中基因表达的信号之一是六苯酮DIF-1。我们发现，在一个无法合成DIF-1的突变体中，约一半的PstO特异性基因的表达受到影响，而其余的似乎与DIF无关。这些结果表明，在没有DIF-1的情况下，PstO细胞某些方面的分化仍可发生。
