Role of an expansin-like molecule in Dictyostelium morphogenesis and regulation of its gene expression by the signal transducer and activator of transcription protein Dd-STATa
Role of an expansin-like molecule in Dictyostelium morphogenesis and regulation of its gene expression by the signal transducer and activator of transcription protein Dd-STATa
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DOI：
10.1111/j.1440-169x.2009.01086.x
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发表时间：
2009-02-01
影响因子：
2.5
通讯作者：
Kawata, Takefumi
中科院分区：
文献类型：
--
作者：
Ogasawara, Shun;Shimada, Nao;Kawata, Takefumi
Expansins是参与植物形态发生的蛋白质，作用于纤维素以延长细胞壁。网柄苔藓是一种拥有扩张素样分子的有机体，但它们的功能尚不清楚。在这项研究中，我们分析了ExpL7(Expansin-like 7)基因，该基因已被鉴定为DD-STATA的假定靶标，DD-STATA是后生动物信号转导和转录激活蛋白(STAT)的Dictyostoma同源物。将ExpL7的启动子片段与LacZ报告基因融合，确定表达模式。正如从内源expL7基因的行为中所预期的那样，expL7/lacZ融合基因在DD-Stata缺失的弹状物中下调。在亲本株中，exL7启动子在前端区被激活。对启动子的突变分析确定了在TIP细胞中表达所必需的序列。此外，还鉴定了pstAB细胞的激活序列。这些序列与抑制子区域一起作用，以防止在虫草和顶端的前孢子和前柄区域异位表达exL7。虽然expL7缺失突变体没有表现出表型变化，但expL7过表达突变体表现出异常的茎形成。这些结果表明，Expansin样分子对网柄苔藓的形态发生有重要作用。
Expansins are proteins involved in plant morphogenesis, exerting their effects on cellulose to extend cell walls. Dictyostelium is an organism that possesses expansin-like molecules, but their functions are not known. In this study, we analyzed the expL7 (expansin-like 7) gene, which has been identified as a putative target of Dd-STATa, a Dictyostelium homolog of the metazoan signal transducer and activator of transcription (STAT) proteins. Promoter fragments of the expL7 were fused to a lacZ reporter and the expression patterns determined. As expected from the behavior of the endogenous expL7 gene, the expL7/lacZ fusion gene was downregulated in Dd-STATa null slugs. In the parental strain, the expL7 promoter was activated in the anterior tip region. Mutational analysis of the promoter identified a sequence that was necessary for expression in tip cells. In addition, an activator sequence for pstAB cells was identified. These sequences act in combination with the repressor region to prevent ectopic expL7 expression in the prespore and prestalk regions of the slug and culminant. Although the expL7 null mutant showed no phenotypic change, the expL7 overexpressor showed aberrant stalk formation. These results indicate that the expansin-like molecule is important for morphogenesis in Dictyostelium.