Dixit Manjusha, Ansseau Eugénie, Tassin Alexandra, Winokur Sara, Shi Rongye, Qian Hong, Sauvage Sébastien, Mattéotti Christel, van Acker Anne M, Leo Oberdan, Figlewicz Denise, Barro Marietta, Laoudj-Chenivesse Dalila, Belayew Alexandra, Coppée Frédérique, Chen Yi-Wen
Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA.
Proc Natl Acad Sci U S A. 2007 Nov 13;104(46):18157-62. doi: 10.1073/pnas.0708659104. Epub 2007 Nov 5.
Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant disorder linked to contractions of the D4Z4 repeat array in the subtelomeric region of chromosome 4q. By comparing genome-wide gene expression data from muscle biopsies of patients with FSHD to those of 11 other neuromuscular disorders, paired-like homeodomain transcription factor 1 (PITX1) was found specifically up-regulated in patients with FSHD. In addition, we showed that the double homeobox 4 gene (DUX4) that maps within the D4Z4 repeat unit was up-regulated in patient myoblasts at both mRNA and protein level. We further showed that the DUX4 protein could activate transient expression of a luciferase reporter gene fused to the Pitx1 promoter as well as the endogenous Pitx1 gene in transfected C2C12 cells. In EMSAs, DUX4 specifically interacted with a 30-bp sequence 5'-CGGATGCTGTCTTCTAATTAGTTTGGACCC-3' in the Pitx1 promoter. Mutations of the TAAT core affected Pitx1-LUC activation in C2C12 cells and DUX4 binding in vitro. Our results suggest that up-regulation of both DUX4 and PITX1 in FSHD muscles may play critical roles in the molecular mechanisms of the disease.
面肩肱型肌营养不良症（FSHD）是一种常染色体显性疾病，与4号染色体长臂亚端粒区域的D4Z4重复序列收缩有关。通过比较FSHD患者肌肉活检的全基因组基因表达数据与其他11种神经肌肉疾病患者的数据，发现配对样同源域转录因子1（PITX1）在FSHD患者中特异性上调。此外，我们发现位于D4Z4重复单元内的双同源盒4基因（DUX4）在患者成肌细胞的mRNA和蛋白质水平均上调。我们进一步表明，DUX4蛋白可激活与Pitx1启动子融合的荧光素酶报告基因以及转染的C2C12细胞中的内源性Pitx1基因的瞬时表达。在电泳迁移率变动分析中，DUX4与Pitx1启动子中一段30个碱基对的序列5'-CGGATGCTGTCTTCTAATTAGTTTGGACCC-3'特异性相互作用。TAAT核心序列的突变影响C2C12细胞中Pitx1-LUC的激活以及体外DUX4的结合。我们的结果表明，FSHD肌肉中DUX4和PITX1的上调可能在该疾病的分子机制中起关键作用。
