The role of basal and myogenic factors in the transcriptional activation of utrophin promoter A: implications for therapeutic up-regulation in Duchenne muscular dystrophy
The role of basal and myogenic factors in the transcriptional activation of utrophin promoter A: implications for therapeutic up-regulation in Duchenne muscular dystrophy
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DOI：
10.1093/nar/29.23.4843
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发表时间：
2001-12-01
影响因子：
14.9
通讯作者：
Davies, KE
中科院分区：
文献类型：
--
作者：
Perkins, KJ;Burton, EA;Davies, KE
杜氏肌营养不良症（DMD）是一种X-连锁隐性肌肉萎缩性疾病，由于缺乏肌肉细胞骨架蛋白，肌营养不良蛋白。肌营养不良蛋白是肌营养不良蛋白的常染色体同源物。我们以前证明，肌营养不良蛋白基因敲除转基因小鼠的肌肉中肌营养不良蛋白的过度表达完全阻止了肌营养不良蛋白缺陷引起的表型。两个独立调控的启动子控制肌营养蛋白的表达，上游启动子（启动子A）在肌肉中受到突触调控。在这项研究中，我们研究了启动子A的基础调控和肌源性诱导。Ap 2和Sp1及其同源DNA基序之间的相互作用对于从最小启动子区域的基础转录至关重要。在体外C2 C12成肌细胞分化过程中，观察到A-utrophin mRNA水平增加2倍。报告基因的表达，其转录由1.3 kb启动子A片段驱动，抑制内源转录本的表达。生肌诱导映射到保守的上游肌肉特异性E盒，该E盒被证明与生肌调节因子结合，在瞬时测定中反式激活启动子高达18倍。本研究为进一步了解肌营养因子表达的调控机制提供了基础，并可能有助于开发有效上调DMD肌营养因子治疗的试剂。
Duchenne muscular dystrophy (DMD) is an X-linked recessive muscle wasting disease caused by the absence of a muscle cytoskeletal protein, dystrophin. Utrophin is the autosomal homologue of dystrophin. We previously demonstrated that overexpression of utrophin in the muscles of dystrophin-null transgenic mice completely prevented the phenotype arising from dystrophin deficiency. Two independently regulated promoters control utrophin expression and the upstream promoter (promoter A) is synaptically regulated in muscle. In this study, we have investigated basal regulation and myogenic induction of promoter A. Interactions between Ap2 and Sp1 and their cognate DNA motifs are critical for basal transcription from the minimal promoter region. During differentiation of C2C12 myoblasts in vitro, a 2-fold increase in A-utrophin mRNA level was observed. Expression of a reporter gene, whose transcription was driven by a 1.3 kb promoter A fragment, paralleled expression of the endogenous transcript. Myogenic induction mapped to a conserved upstream muscle-specific E-box, which was shown to bind myogenic regulatory factors, transactivating the promoter up to 18-fold in transient assays. This study provides a basis for further understanding the regulatory mechanisms that control utrophin expression in muscle and may facilitate the development of reagents to effect therapeutic up-regulation of utrophin in DMD.