McKenzie R W, Brennan M D
Department of Biochemistry and Molecular Biology, School of Medicine, University of Louisville, KY 40292,
Dev Genet. 1998;23(2):119-27. doi: 10.1002/(SICI)1520-6408(1998)23:2<119::AID-DVG4>3.0.CO;2-9.
The cis-acting sequences required for the adult-specific expression pattern of the alcohol dehydrogenase (Adh) gene of the Hawaiian picture-winged fruit fly, Drosophila affinidisjuncta were analyzed by germline transformation. Normally this gene produces two developmentally regulated transcripts. The upstream (distal) promoter produces a distal transcript, which makes up about 80% of the total in adults, while the downstream (proximal) promoter produces a corresponding proximal transcript, which accounts for the remainder. Previously constructed genes lacking regions corresponding to regulatory elements within the Drosophila melanogaster Adh gene or regions known to be required for full expression of the D. affinidisjuncta Adh gene in larvae were analyzed by introduction into the germline of D. melanogaster followed by RNase-protection analysis of RNA levels. In addition, to test a model of preferential promoter utilization by which transcription at the proximal promoter is inhibited by transcription initiated at the upstream distal promoter, a construction lacking the distal promoter was analyzed. Sequences homologous to the adult enhancer of the Adh gene of D. melanogaster appear to play a similar role in the D. affinidisjuncta gene. In contrast to what has been reported for other Drosophila Adh genes, this and some other regulatory elements are shared by the two promoters of the D. affinidisjuncta gene. Taken together, the results favor a model of stage-specific switching between the two promoters of the D. affinidisjuncta gene that involves competition for limiting components stimulating transcription, rather than interference by read-through from the upstream promoter.
通过种系转化分析了夏威夷形象翅果蝇（Drosophila affinidisjuncta）乙醇脱氢酶（Adh）基因成体特异性表达模式所需的顺式作用序列。正常情况下，该基因产生两种受发育调控的转录本。上游（远端）启动子产生一种远端转录本，在成体中约占总量的80%，而下游（近端）启动子产生相应的近端转录本，占其余部分。先前构建的缺少与黑腹果蝇Adh基因内调控元件相对应区域或已知对D. affinidisjuncta Adh基因在幼虫中完全表达所必需区域的基因，通过导入黑腹果蝇种系，随后对RNA水平进行核糖核酸酶保护分析来进行研究。此外，为了测试一种优先启动子利用模型，即近端启动子处的转录受到上游远端启动子起始转录的抑制，对一个缺少远端启动子的构建体进行了分析。与黑腹果蝇Adh基因的成体增强子同源的序列似乎在D. affinidisjuncta基因中发挥类似作用。与其他果蝇Adh基因的报道不同，D. affinidisjuncta基因的两个启动子共享这个和一些其他调控元件。综合来看，结果支持D. affinidisjuncta基因两个启动子之间阶段特异性转换的模型，该模型涉及对刺激转录的有限成分的竞争，而不是上游启动子通读的干扰。
