BRWD1/WDR9纯合突变导致原发性纤毛运动障碍的机制研究

Primary ciliary dyskinesia (PCD) is a heterogeneous genetic disorder characterized by abnormal ciliary ultrastructure or function leading to heterotaxy, impaired mucociliary clearance and recurrent respiratory infections, as well as infertility in males and females. PCD is an autosomal recessive inheritance pattern affecting approximately 1 in 15,000–60,000 individuals. In combination with whole-exome sequencing and homozygosity mapping technologies, we identified a BRWD1/WDR9 homozygous mutation (p.H175Y) in a PCD patient from a consanguinity family. Previous studies of mouse model have identified that the repro5 induced by ENU mutagenesis had a homozygous mutation in Brwd1/Wdr9. Our preliminary study showed knockdown of Brwd1 resulted in abnormal cardiac looping and L-R asymmetry. Zebrafish and mouse models are employed to test the hypohesis that BRWD1/WDR9 is crucial for ciliogenesis and L-R asymmetry. This approach is likely to continue to discover new PCD genes and make screening of existing genes more effective. This study will also increase our mechanistic understanding of how BRWD1 cause PCD. Translating this genetic findings into disease pathways will help stratify patient groups and identify therapeutic targets for PCD that have so far remained undiscovered.

原发性纤毛运动障碍（Primary Ciliary Dyskinesia,PCD）是一类与纤毛相关的常染色隐形遗传病，患者主要表现为右位心、支气管扩张、鼻窦炎和不孕不育等。利用全外显子测序和纯合子定位技术，我们在一例近亲婚配PCD家系鉴定到BRWD1/WDR9纯合突变（p.H175Y）。已有文献表明Brwd1/Wdr9纯合突变导致由ENU人工诱导的repro5小鼠不育不孕。前期我们利用反义Morpholino预实验显示斑马鱼胚胎心脏发育异常以及左右不对称破坏。为进一步证实BRWD1/WDR9为PCD致病基因，我们将以斑马鱼和小鼠为模式生物，研究BRWD1/WDR9 对纤毛生长的调控，探索其导致右位心等内脏异位的分子机制，也即纤毛与左右非对称（L-R asymmetry）决定这一科学问题。本课题有可能鉴定到新的PCD致病基因，并为PCD临床诊断和治疗提供新靶点。

原发性纤毛运动障碍（Primary Ciliary Dyskinesia,PCD）是一类与纤毛相关的常染色隐形遗传病，本研究团队前期利用全外显子测序和纯合子定位技术鉴定到BRWD1/WDR9纯合突变（p.H175Y）。已有文献表明Brwd1/Wdr9纯合突变导致由ENU人工诱导的repro5小鼠不育不孕。我们通过Cas9基因编辑技术成功构建了BRWD1基因敲除纯合体，结果显示缺陷斑马鱼存在心包发育异常和成鱼脊柱侧弯等问题，整体胚胎原位杂交实验证实BRWD1广泛表达，与预期的纤毛相关基因表达模式相符。通过与国内生殖遗传学团队合作，我们共鉴定到3例BRWD1变异病人，其中两例为纯合变异，一例为复合杂合变异。患者都有不育这一典型PCD表现。对患者精子研究发现BRWD1变异蛋白定位发生明显变化，BRWD1变异蛋白聚集在精子头部，其不能正常的定位到精子尾部。进一步分析发现患者精子中内外动力臂蛋白DNAHL1和DNAH5蛋白表达丢失，提示BRWD1可能参与内外动力臂蛋白的组装。本课题有可能鉴定到新的PCD致病基因，并为PCD临床诊断和治疗提供新靶点。