Male infertility caused by defective sperm flagella beat generation due to ODA defects

精子鞭毛是进化保守的细胞器，含有9+2-微管结构，也存在于多个运动纤毛中。鞭毛和纤毛的搏动是由外动力臂产生的。这些多聚体蛋白复合物是由ATP水解产生的，这是微管滑动的驱动力。外动力臂缺陷与运动性纤毛病原发性纤毛运动障碍（PCD, ORPHA 244）有关。这种罕见的遗传性疾病在基因、功能和超微结构上都是异质的。呼吸纤毛和粘膜纤毛清除引起的慢性破坏性气道疾病是PCD的标志性发现，但由于精子鞭毛运动受损（弱精子症）导致的男性不育也是该病的一部分。我们的研究表明，精子鞭毛轴突的组成不同于运动纤毛，如呼吸纤毛。不足为奇的是，一些编码轴突成分的基因被鉴定为与精子鞭毛功能障碍特异性相关，而不影响毛粘清除。在第一个资助期内，我们确定了三种新的遗传缺陷，导致ODA缺陷影响男性生育能力。此外，我们还鉴定了精子鞭毛和活动纤毛的ODA组成，包括连接睾丸和附睾的输出管的ODA组成，并鉴定了细胞类型的特异性差异。我们发现，传出管纤毛跳动对男性生育能力起着重要的作用。然而，针对精子ODA缺陷和其他类型的活动纤毛（如出管纤毛）导致的男性不育的研究只是一个新兴领域，知识仍然有限。因此，在本提案中，我们的目标是：1 .进一步表征人类精子鞭毛和发出管纤毛中的ODA复合物；确定潜在的遗传缺陷和致病机制，导致男性不育负责ODA缺陷。我们将招募先证者，他们将接受详细的临床检查和诊断工作，包括生育/精子功能和/或PCD。蛋白质组学方法将用于鉴定精子ODA复合物的新成分，下一代测序方法将有助于鉴定导致男性不育和/或PCD的遗传缺陷。此外，通过小鼠模型，我们将详细研究传出管纤毛运动对男性生育能力的作用。全面的基因型/表型相关性最终将有助于更好地理解精子鞭毛生物学，从而帮助当前与男性不育相关的诊断工具，并改善基因检测和咨询。

Sperm flagella are evolutionary conserved organelles that contain a 9+2- microtubule structure also present in multiple motile cilia. The flagellar and ciliary beat generation is produced by outer dynein arms (ODA). These multimeric protein complexes generate by ATP hydrolysis, the driving force of microtubule sliding. Outer dynein arm defects are associated with the motile ciliopathy primary ciliary dyskinesia (PCD, ORPHA 244). This rare inherited disorder is genetically, functionally, and ultrastructurally heterogeneous. Respiratory cilia and mucociliary clearance causing a chronic destructive airway disease are hallmark findings in PCD, but also male infertility due to compromised sperm flagella motility (asthenozoospermia) is part of the disease spectrum. Our studies have shown that the composition of sperm flagella axonemes differ from motile cilia such as respiratory cilia. Not surprisingly, several genes encoding for axonemal components were identified to be specifically related to dysfunction of sperm flagella without affecting mucociliary clearance. Within the first funding period we identified three novel genetic defects resulting in ODA defects affecting male fertility. In addition we characterized the ODA composition of sperm flagella and motile cilia, including those of the efferent ducts that connect the testis to the epididymis, and identified cell-type specific differences. We found that efferent duct ciliary beating plays an important role for male fertility. However, research focussing on male infertility due to ODA defects in sperm and other types of motile cilia, such as efferent duct cilia, is just an emerging field and knowledge remains limited. Within this proposal we therefore aim I. to further characterize ODA complexes in human sperm flagella and efferent duct cilia, II. identify underlying genetic defects and pathogenic mechanisms leading to male infertility responsible for ODA defects. We will recruit probands who will undergo detailed clinical examination and diagnostic work up for fertility/sperm function and/or PCD. Proteomic approaches will be used to identify novel components of sperm ODA complexes and next generation sequencing approaches will aid identification of genetic defects responsible for male infertility and/or PCD. Moreover, using a mouse model, we will study in detail the role of efferent duct cilia motility for male fertility. A comprehensive genotype/phenotype correlation will finally lead to a better understanding of sperm flagella biology aiding current diagnostic tools related to male infertility and improving genetic testing and counselling.