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。由于减少的粘膜纤毛清除，PCD个体遭受慢性破坏性的下呼吸道和上呼吸道感染，这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、体轴偏侧缺陷、先天性心脏缺陷、不孕症和罕见的脑积水。动力蛋白臂是纤毛运动所必需的。动力蛋白臂的组分首先在纤毛/鞭毛细胞的细胞质中预组装成多蛋白复合物，然后在纤毛发生期间递送到轴丝。这一过程受进化上保守的称为动力蛋白轴丝组装因子（DNAAFs）的蛋白质的调控。在第一个基金资助期间，我们在两个新的DNAAFs中发现了遗传缺陷（PIH 1D 3/DNAAF 6和C11 orf 70/CFAP 300），其导致动力蛋白臂的有缺陷的细胞质预组装，引起纤毛不运动，气道的粘液纤毛清除紊乱，左/右身体不对称和男性不育的随机化。此外，我们发现，有缺陷的细胞质预组装的动力蛋白武器影响精子鞭毛长度。 通过检测导致PCD的PIH 1D 3/DNAAF 6突变，我们能够描述第一个非综合征性X连锁PCD变体。由于X染色体失活的随机化，我们观察到在女性杂合子PIH 1D 3/DNAAF 6突变携带者中，50%的呼吸细胞显示动力蛋白臂的缺失。然而，到目前为止，对女性杂合突变携带者的临床状况一无所知。在治疗方法方面，重要的是要找出有多少呼吸细胞必须具有有效的气道纤毛清除功能，以及哪些额外的因素参与了动力蛋白臂的细胞质预组装。因此，本建议的目标如下：1） 携带PIH 1D 3/DNAAF 6或其他DNAAF基因突变的其他家族的鉴定2） 女性携带者和半合子突变体以及其他DNAAF中PIH 1D 3/DNAAF 6突变引起的纤毛缺陷的分子、细胞和临床特征3） 由动力蛋白臂的胞质预组装紊乱引起的纤毛和鞭毛长度缺陷的表征 新型DNAAF缺陷的分子和细胞表征5） 新鉴定的和已知的DNAAF之间的蛋白质相互作用的表征该提议的结果将i）扩展临床表型和疾病过程的知识，ii）进一步破译呼吸道细胞以及精子细胞中的动力蛋白臂的细胞质预组装过程，以及iii）导致新的DNAAF基因的鉴定。该项目的结果将改善PCD的诊断和临床护理。