Skeath J B, Carroll S B
Howard Hughes Medical Institute, University of Wisconsin, Madison 53706.
Genes Dev. 1991 Jun;5(6):984-95. doi: 10.1101/gad.5.6.984.
Adult Drosophila possess a large number of sensory organs, including large and small bristles and other types of sensilla, each arising from a single mother cell at particular positions in a reproducible pattern. Genetic studies have shown that sensory organ pattern formation is partly coordinated by a number of structurally similar, potential heterodimer-forming, helix-loop-helix (HLH) regulatory proteins. Here, by localizing regulatory gene expression during the development of normal and mutant imaginal discs, we show that two positive regulators of sensory neurogenesis, the proneural achaete and scute proteins, initially trans-activate each other and are transiently expressed in identical patterns, including clusters of wing ectodermal cells and the individual sensory mother cells that arise from them. Two negative regulators, hairy and extramacrochaete, suppress sensory neurogenesis by selectively repressing achaete and scute gene expression, respectively, but in different spatial domains and at different developmental stages. Surprisingly, we also find that the level of achaete-scute activity influences the level of hairy expression, thereby providing feedback control upon achaete-scute activity and sensory organ formation. Some or all of these interactions may involve specific dimerization reactions between different combinations of HLH proteins.
成年果蝇拥有大量感觉器官，包括大刚毛和小刚毛以及其他类型的感器，每一种都由单个母细胞在特定位置以可重复的模式产生。遗传学研究表明，感觉器官模式形成部分是由一些结构相似、可能形成异源二聚体的螺旋-环-螺旋（HLH）调节蛋白协调的。在这里，通过在正常和突变成虫盘发育过程中定位调节基因的表达，我们发现感觉神经发生的两个正调节因子，即原神经的achaete和scute蛋白，最初相互反式激活，并以相同的模式短暂表达，包括翅外胚层细胞簇以及由它们产生的单个感觉母细胞。两个负调节因子，hairy和extra macrochaete，分别通过选择性抑制achaete和scute基因表达来抑制感觉神经发生，但在不同的空间域和不同的发育阶段。令人惊讶的是，我们还发现achaete-scute活性水平影响hairy表达水平，从而对achaete-scute活性和感觉器官形成提供反馈控制。这些相互作用中的一些或全部可能涉及HLH蛋白不同组合之间的特定二聚化反应。
