Alternative splicing removes an Ets interaction domain from Lozenge during Drosophila eye development
Alternative splicing removes an Ets interaction domain from Lozenge during Drosophila eye development
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DOI：
10.1007/s00427-005-0490-0
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发表时间：
2005-08-01
影响因子：
2.4
通讯作者：
Pollock, JA
中科院分区：
文献类型：
--
作者：
Behan, KJ;Fair, J;Pollock, JA
RUNX家族转录因子的物理和功能特征在脊椎动物和果蝇蛋白质锭剂之间是保守的。负责DNA结合的runt-homology结构域和C-末端在两种蛋白质之间几乎相同。哺乳动物和苍蝇蛋白与非DNA结合伴侣蛋白异二聚化，形成细胞分化过程中基因调控所必需的核心结合因子。哺乳动物蛋白RUNX 1（AML 1/PEBP 2 alpha B）与转录因子Ets-1相互作用，以增加DNA结合和转录激活潜力。哺乳动物RUNX 1的选择性剪接去除了这种合作反式激活所需的结构域。在这项工作中，我们确定了菱形转录单位的结构和地图21个突变。我们发现，菱形转录选择性剪接在眼睛发育过程中，以消除Ets相互作用域。重点放在尖的果蝇同源物的脊椎动物Ets-1蛋白，糖锭和尖的蛋白质都需要激活的表达。我们使用定点突变和酵母双杂交分析，以显示在交替菱形外显子的保守氨基酸是重要的相互作用与尖。此外，锭剂的异位表达足以在Pointed竞争者Yan（ACT）存在下挽救Prospero表达。我们发现，这两个菱形亚型在眼睛发育过程中表达，这两个亚型的转录本的相对比例是敏感的Ras活性的变化。我们认为，在眼睛发育过程中，菱形异构体的功能在不同的角色，无论是相互作用的下游目标的Pointed或独立运作，以建立不同的细胞命运。
Physical and functional characteristics of the RUNX family of transcription factors are conserved between vertebrates and the Drosophila protein Lozenge. The runt-homology domain responsible for DNA binding and also the C-terminus are both nearly identical between the two proteins. The mammalian and fly proteins heterodimerize with a non-DNA binding partner protein to form a core binding factor essential for gene regulation during cell differentiation. The mammalian protein RUNX1 (AML1/PEBP2 alpha B) interacts with the transcription factor Ets-1 to increase DNA binding and transactivation potential. Alternative splicing of the mammalian RUNX1 removes a domain required for this cooperative transactivation. In this work we determine the structure of the lozenge transcription unit and map 21 mutations. We show that the lozenge transcript is alternatively spliced during eye development to remove an Ets interaction domain. Emphasis is placed on Pointed the Drosophila homolog of the vertebrate Ets-1 protein; both Lozenge and Pointed proteins are needed for the activation of prospero expression. We use site-directed mutagenesis and yeast two-hybrid analysis to show that conserved amino acids within the alternate Lozenge exon are important for interaction with Pointed. Furthermore, the ectopic expression of Lozenge is sufficient to rescue Prospero expression in the presence of the Pointed competitor, Yan(ACT). We show that both lozenge isoforms are expressed during eye development and that the relative ratio of the transcripts for the two isoforms is sensitive to changes in Ras activity. We suggest that during eye development, Lozenge isoforms function in divergent roles, either interacting with Pointed on downstream targets or by functioning independently to establish distinct cell fates.