Modifiers of penetrance and expressivity in monogenic dystonia: Insights from systems biology

单基因肌张力障碍的外显率和表达性的修饰因素：来自系统生物学的见解

• 批准号: 318860125
• 负责人: Professor Dr. Hauke Busch
• 金额: --
• 依托单位: Institut für Neurogenetik
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/318860125?language=en
• 关键词: Modifiers; penetrance; expressivity; monogenic; dystonia

Mutations in several genes, including THAP1 (THAP domain-containing apoptosis-associated protein 1), SGCE (sarcoglycan, epsilon), and GCH1 (GTP cyclohydrolase 1) have been confirmed as inherited cause of dystonia. Penetrance of mutations in these genes is about 50%, and there is enormous variable expressivity among the affected carriers. In the first funding period, we focused on genetic modifiers of THAP1 penetrance. For this, we generated 20 iPSC clones from fibroblast lines of 5 affected and 5 unaffected THAP1 mutation carriers. These clones and 14 matched control lines have been differentiated into cortical neuronal lines and used for transcriptome analysis. Further, 13 affected and unaffected THAP1 mutation carriers were whole genome- sequenced and Chromosome Conformation Capture-on-Chip (4C) data of a cortical neuronal line without THAP1 mutation were generated. Using these comprehensive data resources, we demonstrated differential expression of several genes linked to diverse pathways including response to type I interferon, membrane fusion, and mitochondrial fission. For several of those genes, binding of the THAP1 transcription factor has been shown within the respective promoter regions (ENCODE data). Further, the genome data ruled out simple, coding sequence variants in other dystonia genes in the affected carriers. Finally, a common variant within the promoter of KAT6A (lysine acetyltransferase 6A) has been nominated as a potential modifier of THAP1 penetrance based on 3D interaction with the THAP1 gene and segregation in a family.Within this proposal, the overall hypothesis is that penetrance and expressivity of mutations in THAP1, SGCE, or GCH1 are modified by further genetic variants and/or epigenetic marks affecting gene expression and/or metabolites. To substantiate this hypothesis, we will re-analyze existing data for THAP1 with a focus on molecular function combining transcriptome, genome, and regulome data in a trans-Omics multi-variate modeling approach to elucidate synergistic actions relevant to the penetrance of THAP1 mutations (Objective 1). We will broaden our focus to SGCE and GCH1. While the reduced penetrance in SGCE is mainly explained by maternal imprinting, as we demonstrated earlier, the impact of differential methylation and gene expression on the variable expressivity is largely elusive and will be targeted by transcriptome, genome, and methylome studies (Objective 2). Finally, the highly reduced penetrance in, especially, male GCH1 mutation carriers will be investigated by transcriptomics, genome sequencing, and metabolomics (Objective 3). This approach will contribute to a better understanding of molecular variations in THAP1, SGCE, and GCH1 mutation carriers and potentially elucidate factors influencing reduced penetrance and variable expressivity of mutations in these genes.P4 will closly collaborate with P5, P8, and P9 in terms of dystonia, and methodologically with P10 and the Cores in Z2, P1 and P3.

多个基因的突变，包括 THAP1（包含 THAP 结构域的凋亡相关蛋白 1）、SGCE（肌聚糖，ε）和 GCH1（GTP 环水解酶 1）已被证实是肌张力障碍的遗传原因。这些基因突变的外显率约为50%，受影响的携带者之间的表达差异巨大。在第一个资助期，我们专注于 THAP1 外显率的基因修饰剂。为此，我们从 5 个受影响和 5 个未受影响的 THAP1 突变携带者的成纤维细胞系中产生了 20 个 iPSC 克隆。这些克隆和 14 个匹配的对照系已分化为皮质神经元系并用于转录组分析。此外，对 13 个受影响和未受影响的 THAP1 突变携带者进行了全基因组测序，并生成了不带 THAP1 突变的皮质神经元系的染色体构象芯片捕获 (4C) 数据。利用这些全面的数据资源，我们证明了与不同途径相关的几个基因的差异表达，包括对 I 型干扰素、膜融合和线粒体裂变的反应。对于其中几个基因，THAP1 转录因子的结合已显示在各自的启动子区域内（ENCODE 数据）。此外，基因组数据排除了受影响携带者中其他肌张力障碍基因的简单编码序列变异。最后，基于与 THAP1 基因的 3D 相互作用和家族中的分离，KAT6A（赖氨酸乙酰转移酶 6A）启动子内的常见变体被提名为 THAP1 外显率的潜在修饰剂。在该提议中，总体假设是 THAP1、SGCE 或 GCH1 中突变的外显率和表达性受到进一步的遗传变体和/或 影响基因表达和/或代谢物的表观遗传标记。为了证实这一假设，我们将重新分析 THAP1 的现有数据，重点关注跨组学多变量建模方法中结合转录组、基因组和调节组数据的分子功能，以阐明与 THAP1 突变外显率相关的协同作用（目标 1）。我们将把重点扩大到 SGCE 和 GCH1。虽然 SGCE 外显率降低主要是由母体印记解释的，但正如我们之前所证明的，差异甲基化和基因表达对可变表达性的影响在很大程度上是难以捉摸的，并将成为转录组、基因组和甲基化组研究的目标（目标 2）。最后，将通过转录组学、基因组测序和代谢组学研究外显率的高度降低，尤其是男性 GCH1 突变携带者（目标 3）。这种方法将有助于更好地理解 THAP1、SGCE 和 GCH1 突变携带者的分子变异，并有可能阐明影响这些基因突变外显率降低和可变表达率的因素。P4 将在肌张力障碍方面与 P5、P8 和 P9 密切合作，并在方法学上与 P10 和 Z2、P1 和 P3 中的核心合作。