Schwartz C, Locke J, Nishida C, Kornberg T B
Department of Biochemistry and Biophysics, University of California, San Francisco 94143, USA.
Development. 1995 Jun;121(6):1625-35. doi: 10.1242/dev.121.6.1625.
The cubitus interruptus (ci) gene of Drosophila is expressed in all anterior compartment cells in both embryos and imaginal disks where it encodes a putative zinc-finger protein related to the vertebrate Gli and C. elegans Tra-1 proteins. Using ci/lacZ fusions, we located regulatory sequences responsible for the normal pattern of ci expression, and obtained evidence that separate elements regulate its expression in embryos and imaginal disks. Mutants that delete a portion of this regulatory region express ci ectopically in the posterior compartments of their wing imaginal disks and have wings with malformed posterior compartments. Similar deletions of ci/lacZ fusion constructs also result in ectopic posterior compartment expression. Evidence that the engrailed protein normally represses ci in posterior compartments includes the expansion of ci expression into posterior compartment cells that lack engrailed function, diminution of ci expression upon overexpression of engrailed protein in anterior compartment cells, and the ability of engrailed protein to bind to the ci regulatory region in vivo and in vitro. We suggest that engrailed protein directly represses ci expression in posterior compartment cells.
果蝇的间断性肘脉（ci）基因在胚胎和成虫盘的所有前区室细胞中表达，在这些细胞中它编码一种与脊椎动物Gli蛋白和秀丽隐杆线虫Tra-1蛋白相关的假定锌指蛋白。利用ci/lacZ融合基因，我们定位了负责ci正常表达模式的调控序列，并获得证据表明不同元件调控其在胚胎和成虫盘中的表达。缺失该调控区域一部分的突变体在其翅成虫盘的后区室中异位表达ci，并且翅膀的后区室畸形。ci/lacZ融合构建体的类似缺失也导致后区室异位表达。表明正常情况下 engrailed 蛋白在后区室中抑制ci的证据包括：ci表达扩展到缺乏engrailed功能的后区室细胞中；在前区室细胞中过表达engrailed蛋白时ci表达减少；以及engrailed蛋白在体内和体外与ci调控区域结合的能力。我们认为engrailed蛋白直接在后区室细胞中抑制ci表达。
