The role of cytoplasmic pre-assembly of axonemal components in primary ciliary dyskinesia

轴丝成分细胞质预组装在原发性纤毛运动障碍中的作用

• 批准号: 274886879
• 负责人: Professor Dr. Heymut Omran
• 金额: --
• 依托单位: Klinik für Kinder- und Jugendmedizin - Allgemeine Pädiatrie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/274886879?language=en
• 关键词: role; cytoplasmic; pre; assembly; axonemal

Primary Ciliary Dyskinesia (PCD; MIM#242650) is a genetically, functionally and on ultrastructural level heterogeneous group of rare diseases caused by dysfunction of motile cilia. Due to reduced mucociliary clearance PCD individuals suffer from chronic destructive lower and upper airway infections, which cause bronchiectasis and chronic lung failure. Other typical clinical symptoms include respiratory distress of the neonate, chronic otitis media, laterality defects of the body axis, congenital heart defects, infertility and rarely hydrocephalus. Dynein arms are necessary for ciliary motility. The components of dynein arms are first pre-assembled to a multi-protein complex in the cytoplasm of ciliated/ flagellated cells, and then delivered to the axoneme during ciliogenesis. This process is regulated by evolutionarily conserved proteins referred to as dynein axonemal assembly factors (DNAAFs).During the first funding period, we identified genetic defects in two novel DNAAFs (PIH1D3/DNAAF6 and C11orf70/CFAP300) that result in defective cytoplasmic pre-assembly of dynein arms causing ciliary immotility, disturbed mucociliary clearance of the airway, randomization of the left/right body asymmetry and male infertility. Additionally, we found that defective cytoplasmic pre-assembly of dynein arms affects sperm flagella length. By detecting mutations in PIH1D3/DNAAF6 that cause PCD, we were able to describe the first non-syndromic X-linked PCD variant. Due to randomization of X-chromosomal inactivation, we observed in female heterozygous PIH1D3/DNAAF6 mutation carriers that approx. 50% of respiratory cells show absence of dynein arms. However, so far nothing is known about the clinical status of female heterozygous mutation carriers. In terms of therapeutic approaches, it is important to find out how many respiratory cells have to be functional for effective ciliary clearance of the airways and which additional factors are involved in the cytoplasmic pre-assembly of dynein arms. Therefore, the objectives of this current proposal are as follows:1) Identification of additional families carrying mutations in PIH1D3/DNAAF6 or in other DNAAF genes2) Molecular, cellular and clinical characterization of the ciliary defect caused by mutations in PIH1D3/DNAAF6 in female carriers and hemizygous mutants and in other DNAAFs3) Characterization of the ciliary and flagellar length defects caused by disturbed cytoplasmic preassembly of dynein arms 4) Molecular and cellular characterization of novel DNAAF defects 5) Characterization of protein interactions between newly identified and known DNAAFsThe results of this proposal will i) expand knowledge of the clinical phenotype and disease course, ii) further decipher the process of cytoplasmic pre-assembly of dynein arms in respiratory as well as sperm cells, and iii) lead to the identification of new DNAAF genes. The results of this project will improve diagnostics as well as clinical care for PCD.

原发性纤毛运动障碍（PCD；MIM#242650）是一组由运动纤毛功能障碍引起的遗传、功能和超微结构水平异质性罕见疾病。由于粘膜纤毛清除能力降低，PCD 患者会遭受慢性破坏性下呼吸道和上呼吸道感染，从而导致支气管扩张和慢性肺衰竭。其他典型的临床症状包括新生儿呼吸窘迫、慢性中耳炎、身体轴偏侧缺陷、先天性心脏病、不孕症和罕见的脑积水。动力蛋白臂对于纤毛运动是必需的。动力蛋白臂的成分首先在纤毛/鞭毛细胞的细胞质中预组装成多蛋白复合物，然后在纤毛发生过程中递送至轴丝。这一过程受到称为动力蛋白轴丝组装因子 (DNAAF) 的进化保守蛋白的调节。在第一个资助期间，我们发现了两种新型 DNAAF（PIH1D3/DNAAF6 和 C11orf70/CFAP300）中的遗传缺陷，这些缺陷导致细胞质预组装缺陷动力蛋白臂导致纤毛不运动、气道粘膜纤毛清除紊乱、随机化左右身体不对称和男性不育。此外，我们发现动力蛋白臂的细胞质预组装缺陷会影响精子鞭毛的长度。 通过检测导致 PCD 的 PIH1D3/DNAAF6 突变，我们能够描述第一个非综合征性 X 连锁 PCD 变异。由于 X 染色体失活的随机性，我们在女性杂合子 PIH1D3/DNAAF6 突变携带者中观察到大约。 50% 的呼吸细胞缺乏动力蛋白臂。然而，迄今为止，对于女性杂合突变携带者的临床状况尚不清楚。就治疗方法而言，重要的是要找出需要多少呼吸细胞才能有效地纤毛清除气道，以及哪些其他因素参与动力蛋白臂的细胞质预组装。因此，当前提案的目标如下：1) 鉴定携带 PIH1D3/DNAAF6 或其他 DNAAF 基因突变的其他家族2) 女性携带者中 PIH1D3/DNAAF6 突变引起的纤毛缺陷的分子、细胞和临床特征和半合子突变体以及其他 DNAAF 3) 动力蛋白臂细胞质预组装紊乱引起的纤毛和鞭毛长度缺陷的表征4) 新型 DNAAF 缺陷的分子和细胞表征 5) 新鉴定的和已知的 DNAAF 之间蛋白质相互作用的表征 该提案的结果将 i) 扩展对临床表型和疾病过程的了解，ii) 进一步破译细胞质预组装的过程呼吸细胞和精子细胞中动力蛋白臂的变化，以及 iii) 导致新 DNAAF 基因的鉴定。该项目的结果将改善 PCD 的诊断和临床护理。