Iverson L E, Mottes J R, Yeager S A, Germeraad S E
Division of Neurosciences, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA.
J Neurobiol. 1997 May;32(5):457-68.
Alternative splicing of precursor RNA enables a single gene to encode multiple protein isoforms with different functional characteristics and tissue distributions. Differential splicing of Drosophila Shaker (Sh) gene transcripts regulates the tissue-specific expression of kinetically distinct potassium ion channels throughout development. Regulation of Sh alternative splicing is being examined in germline transformants using lacZ as a reporter gene. P-element constructs were generated in which one or both of the two mutually exclusive Sh 3' acceptor sites were positioned in the same translational reading frame as the lacZ coding sequences. The constructs were introduced into the germline and the transgenic animals examined for tissue-specific beta-galactosidase expression patterns. Some tissues exhibit "promiscuous" splicing; these tissues are competent to splice to either 3' acceptor even when both are present on the same pre-mRNA. In other tissues splice choice results from competition between the two 3' sites; these tissues can splice to either site when it is the only available 3' acceptor, but when given a choice will splice to only one of the two 3' acceptors. In some tissues, splicing occurs exclusively at only one of the 3' acceptor sites; these tissues are not competent to splice to one of the sites even if it is the only 3' acceptor present on the pre-mRNA. These results suggests that multiple, distinct regulatory modes are operating to control tissue-specific alternative splicing of Sh 3' domains and are discussed in terms of potential underlying mechanisms for regulating the tissue-specific expression of alternatively spliced genes.
前体RNA的可变剪接使单个基因能够编码具有不同功能特征和组织分布的多种蛋白质异构体。果蝇Shaker（Sh）基因转录本的差异剪接在整个发育过程中调节动力学上不同的钾离子通道的组织特异性表达。正在使用lacZ作为报告基因在种系转化体中研究Sh可变剪接的调控。构建了P因子载体，其中两个相互排斥的Sh 3'受体位点中的一个或两个与lacZ编码序列位于相同的翻译阅读框中。将这些载体导入种系，并检查转基因动物的组织特异性β-半乳糖苷酶表达模式。一些组织表现出“混杂”剪接；即使两个3'受体都存在于同一前体mRNA上，这些组织也能够剪接到任一3'受体。在其他组织中，剪接选择是由两个3'位点之间的竞争导致的；当只有一个3'受体可用时，这些组织可以剪接到任一受体，但当有选择时，只会剪接到两个3'受体中的一个。在一些组织中，剪接仅发生在两个3'受体位点中的一个；即使该位点是前体mRNA上唯一存在的3'受体，这些组织也不能剪接到该位点。这些结果表明，多种不同的调控模式在控制Sh 3'结构域的组织特异性可变剪接，并从调节可变剪接基因组织特异性表达的潜在潜在机制方面进行了讨论。
