Sequence requirements for myosin gene expression and regulation in Caenorhabditis elegans.
Sequence requirements for myosin gene expression and regulation in Caenorhabditis elegans.
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秀丽隐杆线虫肌球蛋白基因表达和调控的序列要求。
DOI：
10.1093/genetics/135.2.385
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发表时间：
1993
期刊：
影响因子：
3.3
通讯作者：
Fire,A
中科院分区：
文献类型：
--
作者：
Okkema,PG;Harrison,SW;Plunger,V;Aryana,A;Fire,A
秀丽线虫的四个基因编码肌型特异性肌球蛋白重链亚型：Myo-1和myo-2在咽部肌肉中表达；UNC-54和myo-3在体壁肌肉中表达。我们已经使用转化拯救和LacZ融合分析来确定在发育过程中对调节肌球蛋白基因表达的序列要求。所有四个基因都存在多个组织特异性激活元件。对于这四个基因中的每一个，编码区上游的序列都是组织特异性启动子，正如它们能够驱动报告基因(LacZ)在适当的肌肉类型中表达所表明的那样。每个基因至少包含一个额外的组织特异性调控元件，其定义是能够增强异源启动子在适当肌肉类型中的表达。在UNC-54的抢救实验中，发现了两个明显独立于组织特异性的进一步要求：3‘非编码区内的序列是活性所必需的，而5’端附近的内含子增加了表达水平。一般内含子的刺激明显不受内含子序列的影响，这表明剪接是一种机械效应。为了进一步确定肌球蛋白基因启动子的特征和检测基因组中增强子序列的类型，我们启动了线虫基因组DNA的筛选，以寻找能够增强myo-2启动子的片段。从这一筛选中回收的增强剂的性质表明，启动子对增强剂的反应能力仅限于肌肉细胞。
Four Caenorhabditis elegans genes encode muscle-type specific myosin heavy chain isoforms: myo-1 and myo-2 are expressed in the pharyngeal muscles; unc-54 and myo-3 are expressed in body wall muscles. We have used transformation-rescue and lacZ fusion assays to determine sequence requirements for regulated myosin gene expression during development. Multiple tissue-specific activation elements are present for all four genes. For each of the four genes, sequences upstream of the coding region are tissue-specific promoters, as shown by their ability to drive expression of a reporter gene (lacZ) in the appropriate muscle type. Each gene contains at least one additional tissue-specific regulatory element, as defined by the ability to enhance expression of a heterologous promoter in the appropriate muscle type. In rescue experiments with unc-54, two further requirements apparently independent of tissue specificity were found: sequences within the 3' non-coding region are essential for activity while an intron near the 5' end augments expression levels. The general intron stimulation is apparently independent of intron sequence, indicating a mechanistic effect of splicing. To further characterize the myosin gene promoters and to examine the types of enhancer sequences in the genome, we have initiated a screen of C. elegans genomic DNA for fragments capable of enhancing the myo-2 promoter. The properties of enhancers recovered from this screen suggest that the promoter is limited to muscle cells in its ability to respond to enhancers.