Shimada Nao, Kawata Takefumi
Department of Biology, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan.
Eukaryot Cell. 2007 Jun;6(6):1030-40. doi: 10.1128/EC.00035-07. Epub 2007 Apr 13.
Dd-STATa, a Dictyostelium discoideum homologue of metazoan STAT transcription factors, is necessary for culmination. We created a mutant strain with partial Dd-STATa activity and used it to screen for unlinked suppressor genes. We screened approximately 450,000 clones from a slug-stage cDNA library for their ability to rescue the culmination defect when overexpressed. There were 12 multicopy suppressors of Dd-STATa, of which 4 encoded segments of a known noncoding RNA, dutA. Expression of dutA is specific to the pstA zone, the region where Dd-STATa is activated. In suppressed strains the expression patterns of several putative Dd-STATa target genes become similar to the wild-type strain. In addition, the amount of the tyrosine-phosphorylated form of Dd-STATa is significantly increased in the suppressed strain. These results indicate that partial copies of dutA may act upstream of Dd-STATa to regulate tyrosine phosphorylation by an unknown mechanism.
Dd-STATa是后生动物STAT转录因子在盘基网柄菌中的同源物，对细胞聚集是必需的。我们构建了一个具有部分Dd-STATa活性的突变菌株，并利用它来筛选非连锁的抑制基因。我们从蛞蝓阶段的cDNA文库中筛选了约450,000个克隆，以检测它们在过表达时拯救细胞聚集缺陷的能力。有12个Dd-STATa的多拷贝抑制子，其中4个编码已知非编码RNA dutA的片段。dutA的表达特异性地定位于pstA区，即Dd-STATa被激活的区域。在被抑制的菌株中，几个假定的Dd-STATa靶基因的表达模式变得与野生型菌株相似。此外，在被抑制的菌株中，Dd-STATa的酪氨酸磷酸化形式的量显著增加。这些结果表明，dutA的部分拷贝可能在Dd-STATa的上游起作用，通过未知机制调节酪氨酸磷酸化。
