TEMPORAL COORDINATION OF REGULATORY GENE-EXPRESSION BY THE STEROID-HORMONE ECDYSONE
TEMPORAL COORDINATION OF REGULATORY GENE-EXPRESSION BY THE STEROID-HORMONE ECDYSONE
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DOI：
10.1002/j.1460-2075.1992.tb05501.x
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发表时间：
1992-11-01
期刊：
影响因子：
11.4
通讯作者：
THUMMEL, CS
中科院分区：
文献类型：
--
作者：
KARIM, FD;THUMMEL, CS
在果蝇中，类固醇激素蜕皮激素的脉冲作为触发主要胚胎后发育转变的时间信号。这些脉冲中最具特征的是，当它触发变态时，会激活多染色体中的一系列气泡。对这种激素的主要反应是早期的一小段喘息。这些泡体编码调节蛋白，既抑制自身的表达，又激活大量的晚期次级反应基因。我们使用Northern blot分析从分期动物和培养器官中分离的RNA，研究了三个主要反应调节基因E75， BR-C和EcR的转录。值得注意的是，它们在幼虫后期的转录模式可以根据对不同蜕皮激素浓度的两种反应来定义。I类转录本（E74B和EcR）在中3龄幼虫中受ecdysone滴度较低但升高的影响而被诱导。当激素浓度在3龄后期达到峰值时，这些转录本受到抑制，II类rna （E74A、E75A和E75B）被诱导。BR-C rna似乎同时具有I类和II类特征。这些数据表明，激素脉冲的相对简单的轮廓包含了关键的时间信息，这些信息被转导成初级反应调节基因活性的波。
In Drosophila, pulses of the steroid hormone ecdysone function as temporal signals that trigger the major postembryonic developmental transitions. The best characterized of these pulses activates a series of puffs in the polytene chromosomes as it triggers metamorphosis. A small set of early puffs is induced as a primary response to the hormone. These puffs encode regulatory proteins that both repress their own expression and activate a large set of late secondary response genes. We have used Northern blot analysis of RNA isolated from staged animals and cultured organs to study the transcription of three primary response regulatory genes, E75, BR-C and EcR. Remarkably, their patterns of transcription in late larvae can be defined in terms of two responses to different ecdysone concentrations. The class I transcripts (E74B and EcR) are induced in mid-third instar larvae in response to the low, but increasing, titer of ecdysone. As the hormone concentration peaks in late third instar larvae, these transcripts are repressed and the class II RNAs (E74A, E75A and E75B) are induced. The BR-C RNAs appear to have both class I and class II characteristics. These data demonstrate that the relatively simple profile of a hormone pulse contains critic-al temporal information that is transduced into waves of primary response regulatory gene activity.