Watanabe Tomoji, Takagi Akio, Sasagawa Noboru, Ishiura Shoichi, Nakase Hirofumi
Department of Neurology, Toranomon Hospital and Okinaka Memorial Institute for Medical Research, 222 Toranomon, Minato-ku, Tokyo 105-0001, Japan.
Neurosci Res. 2004 May;49(1):47-54. doi: 10.1016/j.neures.2004.01.008.
The triplet repeats mutation, which causes myotonic dystrophy 1 (DM1), is thought to have a dominant negative effect on RNA levels. In light of previous results using differential display analysis, the present study focused on the expression of CUG binding protein 1 (CUGBP1) mRNA. Northern blot analysis demonstrated that the quantity of CUGBP1 mRNA in three DM1 patients was approximately 70% of that observed in three normal controls (P < 0.05). In addition, a semi-quantitative RT-PCR assay showed that the relative amount of CUGBP1 mRNA was reduced in muscle biopsy samples from 10 DM1 patients compared to that from five normal individuals (P < 0.01) and 10 myopathic disease controls (P < 0.01). The amount of CUGBP1 mRNA was negatively correlated with the size of the CTG expansion (r = -0.85, P < 0.05). In vitro RNA-RNA binding experiments demonstrated that the incubation of expanded CUG repeats with CUGBP1 RNA generated a higher molecular weight band, which was digested by RNase III. The CUGBP1 mRNA was found to contain several CAG repeat sequences. These results suggest that the CUG expansion may bind to complementary sequences within the CUGBP1 mRNA and that this molecular interaction may affect CUGBP1 mRNA expression in DM1.
导致强直性肌营养不良1型（DM1）的三联体重复突变被认为对RNA水平具有显性负效应。鉴于先前使用差异显示分析的结果，本研究聚焦于CUG结合蛋白1（CUGBP1）mRNA的表达。Northern印迹分析表明，三名DM1患者中CUGBP1 mRNA的量约为三名正常对照中观察到的量的70%（P < 0.05）。此外，半定量RT-PCR分析显示，与五名正常个体（P < 0.01）和十名肌病疾病对照（P < 0.01）的肌肉活检样本相比，十名DM1患者的肌肉活检样本中CUGBP1 mRNA的相对量减少。CUGBP1 mRNA的量与CTG扩增的大小呈负相关（r = -0.85，P < 0.05）。体外RNA-RNA结合实验表明，将扩展的CUG重复序列与CUGBP1 RNA一起孵育会产生一条更高分子量的条带，该条带被RNase III消化。发现CUGBP1 mRNA包含几个CAG重复序列。这些结果表明，CUG扩增可能与CUGBP1 mRNA内的互补序列结合，并且这种分子相互作用可能影响DM1中CUGBP1 mRNA的表达。
