Gutjahr T, Vanario-Alonso C E, Pick L, Noll M
Institute for Molecular Biology II, University of Zürich, Switzerland.
Mech Dev. 1994 Nov;48(2):119-28. doi: 10.1016/0925-4773(94)90021-3.
The paired (prd) gene of Drosophila belongs to the pair-rule class of segmentation genes involved in establishing the metameric organization of the Drosophila body plan. The complex expression pattern of prd has previously been shown to depend upon a number of segmentation genes, including gap and pair-rule genes. In an attempt to characterize and analyze the regulatory regions necessary and sufficient for prd expression, we have identified an 18-kb genomic fragment, consisting of the transcribed portion of prd and 10 kb of 5'- and 5 kb of 3'-flanking region, that is able to rescue prd mutant embryos to full viability. Analysis of a series of prd-lacZ fusion constructs containing progressively reduced lengths of prd 5'-flanking sequences delimits different cis-regulatory regions. The entire 5'-flanking region directs fusion gene expression in a pattern similar, but not identical, to the endogenous prd protein pattern. This 10-kb fragment contains both activator and repressor regions that mediate the establishment of the seven-stripe prd pattern, as well as the splitting into anterior and posterior stripes for the 14-stripe expression phase. The prd intron in combination with a minimal upstream region (0.15 kb) is able to direct low levels of prd-lacZ fusion gene expression in stripes. Information for expression of the anterior dorsal spot and of the early seven-stripe pattern is located downstream of the prd coding region. We propose that regulation of prd by pair-rule and gap gene products is mediated by upstream and downstream cis-regulatory elements. Regulation during separate but overlapping phases of expression by separable regulatory regions might be a general characteristic of segmentation genes.
果蝇的配对（prd）基因属于参与建立果蝇身体计划体节组织的体节极性基因类别。之前已表明，prd复杂的表达模式依赖于许多体节基因，包括缺口基因和体节极性基因。为了表征和分析prd表达所必需且足够的调控区域，我们鉴定出一个18 kb的基因组片段，它由prd的转录部分以及10 kb的5'侧翼区域和5 kb的3'侧翼区域组成，该片段能够将prd突变胚胎拯救至完全存活。对一系列包含逐渐缩短的prd 5'侧翼序列长度的prd - lacZ融合构建体的分析确定了不同的顺式调控区域。整个5'侧翼区域指导融合基因的表达，其模式与内源性prd蛋白模式相似但不完全相同。这个10 kb的片段包含激活区域和抑制区域，它们介导了七条带prd模式的建立，以及在14条带表达阶段分裂为前后带。prd内含子与一个最小上游区域（0.15 kb）结合能够指导融合基因在条带中低水平表达。前背斑和早期七条带模式的表达信息位于prd编码区域的下游。我们提出，体节极性基因和缺口基因产物对prd的调控是由上游和下游顺式调控元件介导的。由可分离的调控区域在表达的不同但重叠阶段进行调控可能是体节基因的一个普遍特征。
