Mastick G S, Scholnick S B
Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213.
Mol Cell Biol. 1992 Dec;12(12):5659-66. doi: 10.1128/mcb.12.12.5659-5666.1992.
Glial expression of the Drosophila dopa decarboxylase gene (Ddc) is repressed by a regulatory region located approximately 1 kb upstream of the transcriptional start site. We have used in vitro mutagenesis and germ line transformation to determine which elements within the Ddc promoter mediate repression. Our evidence suggests that the hypodermal cell activator elements IIA and IIB play a major role in the transcriptional regulation of Ddc in glial cells. A variety of mutations demonstrate that element IIA is a strong glial activator element and that element IIB is necessary for glial repression. Although these two regulatory elements are nearly identical in sequence, our data suggest that they are not redundant. Altering the wild-type number and spacing of elements IIA and IIB indicates that the wild-type arrangement of this repeat is critical for repression. We conclude that these key elements of the Ddc promoter regulate both activation and repression in glia.
果蝇多巴脱羧酶基因（Ddc）在神经胶质细胞中的表达受到位于转录起始位点上游约1 kb处的一个调控区域的抑制。我们利用体外诱变和生殖系转化来确定Ddc启动子中的哪些元件介导抑制作用。我们的证据表明，皮下细胞激活元件IIA和IIB在神经胶质细胞中Ddc的转录调控中起主要作用。多种突变表明，元件IIA是一个强大的神经胶质细胞激活元件，元件IIB是神经胶质细胞抑制所必需的。尽管这两个调控元件在序列上几乎相同，但我们的数据表明它们并非冗余。改变元件IIA和IIB的野生型数量和间距表明，该重复序列的野生型排列对于抑制作用至关重要。我们得出结论，Ddc启动子的这些关键元件调节神经胶质细胞中的激活和抑制作用。
