Function of DMAHP/Six5 gene and the involvement in myotonic dystrophy

DMAHP/Six5基因的功能及其与强直性肌营养不良的关系

基本信息

批准号：
10670143
负责人：
KAWAKAMI Kiyoshi
金额：
$ 1.73万
依托单位：
Jichi Medical School
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10670143/
关键词：
myotonic dystrophy DMAHP Six5 gene transcription start site CTG repeat target genes transcription regulatory element myogenin Eya genes Six5 Sp1 Sp3

项目摘要

To reveal the involvement of DMAHP/Six5 in pathogenesis of myotonic dystrophy (DM) at the molecular level, we clarified several points described below.(1)We identified two transcription start sites common to skeletal muscle, heart, and embryo and one site specific to early embryo (El1). All of these sites reside downstream of the CTG repeat. This observation excludes the possibility that the CUG repeat in the transcribed mRNA causes aberrant splicing or translation leading to DM.(2)We analyzed the transcription regulatory elements of the DMAHP/Six5 gene in P19 cells and identified three Sp1/Sp3 sites as positive regulatory elements and two negative regulatory elements, to one of which an unidentified factor binds.(3)To identify target genes of DMAHP/Six5 protein, we constructed constitutive active VPl6-Six5 and constitutive repressive Eng-Six5. The constitutive active Six5 functions as expected but the constitutive repressive Six5 did not. The screening of the possible target genes are ongoing using microarray by infecting adenovirus vector containing the VP16-Six5 into cultured cells.(4)The myogenin promoter has been identified as a target gene for Six1, Six4 protein. We found out that the promoter could be activated by Six5. Co-transfection of Eya genes greatly enhanced the activation. This result suggests a new insight into the DM pathogenesis that diminished expression of Six5 lead to weak cooperative action with Eya leading to reduced expression of myogenin. This might cause the immaturation of skeletal muscle.

为了揭示DMAHP/SIX5参与分子水平上肌营养不良症（DM）的发病机理，我们阐明了下面描述的几个点。（1）我们确定了两个转录起始位点，骨骼肌，心脏，心脏和胚胎和一个特定部位的特定于骨骼肌肉，心脏和一个。到早期胚胎（EL1）。所有这些站点都驻留在CTG重复的下游。该观察结果排除了转录mRNA中的CUG重复引起异常的剪接或翻译导致DM的剪接或翻译。元素和两个负调控元件，其中一个不明显的因子结合。（3）为了识别DMAHP/SIX5蛋白的靶基因，我们构建了组成型Active VPL6-SIX5和构成抑制ENG-SIX5。组成型Active SIX5按预期功能，但构型抑制六5均不做。通过微阵列，通过将含有VP16-SIX5的腺病毒载体感染到培养的细胞中，使用微阵列进行筛查。我们发现启动子可以被六5激活。 EYA基因的共转染大大增强了激活。该结果表明，对DM发病机理有了新的见解，即six5的表达降低导致与EYA的合作作用较弱，从而导致肌蛋白的表达降低。这可能会导致骨骼肌不成熟。