Brenner R, Thomas T O, Becker M N, Atkinson N S
Department of Zoology, University of Texas at Austin 78712-1064, USA.
J Neurosci. 1996 Mar 1;16(5):1827-35. doi: 10.1523/JNEUROSCI.16-05-01827.1996.
The electrical properties of a cell are produced by the complement of ion channels that it expresses. To understand how ion-channel gene expression is regulated, we are studying the tissue-specific regulation of the slowpoke (slo) Ca(2+)-activated K+ channel gene. This gene is expressed in the central and peripheral nervous system, in midgut and tracheal cells, and in the musculature of Drosophila melanogaster. The entire transcriptional control region has been cloned previously and shown to reproduce the tissue and developmental expression pattern of the endogenous gene. Here we demonstrate that s/o has at least four promoters distributed over approximately 4.5 kb of DNA. Promoter C1 and C1c display a TATA box-like sequence at the appropriate distance from the transcription start site. Promoters C1b and C2, however, are TATA-less promoters. C1, C1b, and C1c transcripts differ in their leader sequence but share a common translation start site. C2 transcripts incorporate a new translation start site that appends 17 amino acids to the N terminus of the encoded protein. Deletion analysis was used to identify sequences important for tissue-specific expression. We used a transgenic in vivo expression system in which all tissues and developmental stages can be assayed easily. Six nested deletions were transformed into Drosophila, and the expression pattern was determined using a lacZ reporter in both dissected tissues and sectioned animals. We have identified different sequences required for expression in the CNS, midgut, tracheal cells, and muscle.
细胞的电特性由其表达的离子通道组合产生。为了解离子通道基因表达是如何被调控的，我们正在研究慢poke（slo）钙激活钾通道基因的组织特异性调控。该基因在黑腹果蝇的中枢和外周神经系统、中肠和气管细胞以及肌肉组织中表达。整个转录控制区域先前已被克隆，并显示可重现内源基因的组织和发育表达模式。在这里，我们证明s/o至少有四个启动子，分布在约4.5 kb的DNA上。启动子C1和C1c在距转录起始位点适当距离处显示出类似TATA框的序列。然而，启动子C1b和C2是无TATA框的启动子。C1、C1b和C1c转录本的前导序列不同，但共享一个共同的翻译起始位点。C2转录本包含一个新的翻译起始位点，该位点在编码蛋白的N末端附加了17个氨基酸。缺失分析用于鉴定对组织特异性表达重要的序列。我们使用了一种转基因体内表达系统，在该系统中可以轻松检测所有组织和发育阶段。六个嵌套缺失被转化到果蝇中，并使用lacZ报告基因在解剖组织和切片动物中确定表达模式。我们已经鉴定出在中枢神经系统、中肠、气管细胞和肌肉中表达所需的不同序列。
