Spatial and temporal expression of a Polysphondylium spore-specific gene
Spatial and temporal expression of a Polysphondylium spore-specific gene
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DOI：
10.1006/dbio.2000.9768
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发表时间：
2000-08-01
影响因子：
2.7
通讯作者：
Cox, EC
中科院分区：
文献类型：
--
作者：
Gregg, KY;Cox, EC
在细胞黏液霉菌中，聚多酚球状细胞团周期性地从最终发酵剂的底部释放出来。这些螺纹经历了从球状对称到径向对称的形态发生转变，其特征是在螺纹面上早期出现了径向对称的预图案。在以前的实验中，形态发生是通过观察前柄细胞标记来进行的。在这里，我们描述了一个孢子皮基因的分离和鉴定，该基因的表达模式是前柄模式的负像。为了研究SP-45基因调控的分子机制，我们克隆并分析了SP-45启动子。缺失分析将单个正调控元件(Pre)定位于上游编码序列的-246至-352位之间的106bp片段。该片段可进一步分为启动子-近端和启动子-远端的Pre，以及它们之间的一个29bp的序列。当与不起作用的基本启动子融合时，远端的PRE可以调节前孢子的表达。远端的Pre含有两个相邻的基本元件，一个Gr盒(GTGATATAGTGG)和一个TA盒(TAATATT)。每个元件都可以独立地驱动前孢子细胞特异性报告基因的表达，当它们被整合到一个非功能性启动子中时。我们的结果还表明，前孢子细胞特异的基因表达只受正向调控，没有证据表明存在孢子特异的增强子或顺式作用的负调控元件。通过将GFP融合到SP-45的C末端，我们证明了SP45在索氏菌中的分级基因表达受到位于SP-45编码序列内的序列的调控。该蛋白质的时间和空间表达模式，与前柄表达模式一起，明确地表明，在轮生中出现的径向对称性是由位置坐标系建立的，细胞分选在这一过程中几乎没有作用。(C)2000年学术出版社。
In the cellular slime mold Polysphondylium spherical masses of cells are periodically released from the base of the culminating sorogen. These whorls undergo a morphogenetic transformation from spherical to radial symmetry, marked by the early emergence of a radially symmetric prepattern on the whorl surface. In previous experiments, morphogenesis was followed by observing prestalk cell markers. Here we describe the isolation and characterization of a spore coat gene whose expression pattern is the negative image of the prestalk pattern. To study the molecular mechanism of sp-45 gene regulation, we have cloned and analyzed the sp-45 promoter. Deletion analysis localized a single positive regulatory element (PRE) to a 106-bp fragment between positions -246 and -352 of the upstream coding sequence. This fragment can be further divided into a promoter-proximal and promoter-distal PRE and a 29-bp sequence between them. The distal PRE can regulate prespore expression when fused to a nonfunctioning basal promoter. The distal PRE contains two adjacent essential elements, a Gr box (GTGATATAGTGG) and a TA box (TAATATATT). Each element can drive prespore cell-specific reporter gene expression independently when incorporated into a nonfunctional promoter. Our results also show that prespore cell-specific gene expression is solely under positive regulation, with no evidence for spore-specific enhancers or cis-acting negative regulatory elements. By fusing GFP to the C-terminus of sp-45, we have demonstrated that the graded gene expression of SP45 in the sorogen is regulated by a sequence lying within the sp-45 coding sequence. The temporal and spatial expression pattern of this protein, taken together with the prestalk expression pattern, demonstrates unambiguously that the radial symmetries that emerge in the whorl are established by a system of positional coordinates and that cell sorting plays little if any role in this process. (C) 2000 Academic Press.