Bi-allelic Mutations in TTC29 Cause Male Subfertility with Asthenoteratospermia in Humans and Mice
Bi-allelic Mutations in TTC29 Cause Male Subfertility with Asthenoteratospermia in Humans and Mice
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TTC29 的双等位基因突变导致人类和小鼠男性生育能力低下并伴有弱精子症
DOI：
10.1016/j.ajhg.2019.10.010
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发表时间：
2019-12-05
影响因子：
9.8
通讯作者：
Zhang, Feng
中科院分区：
文献类型：
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作者：
Liu, Chunyu;He, Xiaojin;Zhang, Feng
多鞭毛形态异常（multiple morphological abnormalities of the flagella，MMAF）是严重弱畸形精子症的一种类型，其特征是存在严重鞭毛畸形的不动精子。MMAF是一种遗传异质性疾病，已知的MMAF相关基因仅占人类MMAF病例的约60%。在这里，我们进行了全外显子组测序，并确定了TTC 29（tetratricopeptide repeat domain 29）基因的双等位基因截短突变在三个（3.8%）无关的情况下，从一个队列的80名MMAF影响中国汉族男性。TTC 29优先在睾丸中表达，并且TTC 29蛋白含有在纤毛和鞭毛相关功能中发挥重要作用的三肽重复结构域。所有携带TTC 29突变的男性都表现出典型的MMAF表型，轴丝和/或其他轴丝周围结构严重紊乱。携带TTC 29突变的男性精子的免疫荧光检测显示TTC 29缺陷和鞭毛内转运复合物B相关蛋白（TTC 30 A和IFFT 52）的染色显着减少。我们还通过使用CRISPR-Cas9技术生成了TtC 29突变的小鼠模型。值得注意的是，TtC 29突变的雄性小鼠也表现出精子活力降低、鞭毛超微结构异常和雄性生育力低下。此外，对携带TTC 29突变的小鼠和男性进行卵胞浆内精子注射始终获得令人满意的结果。总之，我们在人类和小鼠中的实验观察表明，TTC 29的双等位基因突变作为一种重要的遗传病因，可以诱导MMAF相关的弱畸形精子症。本研究为临床诊断和辅助生殖治疗提供了有效的指导。
As a type of severe asthenoteratospermia, multiple morphological abnormalities of the flagella (MMAF) are characterized by the presence of immotile spermatozoa with severe flagellar malformations. MMAF is a genetically heterogeneous disorder, and the known MMAF-associated genes can only account for approximately 60% of human MMAF cases. Here we conducted whole-exome sequencing and identified bi-allelic truncating mutations of the TTC29 (tetratricopeptide repeat domain 29) gene in three (3.8%) unrelated cases from a cohort of 80 MMAF-affected Han Chinese men. TTC29 is preferentially expressed in the testis, and TTC29 protein contains the tetratricopeptide repeat domains that play an important role in cilia- and flagella-associated functions. All of the men harboring TTC29 mutations presented a typical MMAF phenotype and dramatic disorganization in axonemal and/or other peri-axonemal structures. Immunofluorescence assays of spermatozoa from men harboring TTC29 mutations showed deficiency of TTC29 and remarkably reduced staining of intraflagellar-transport-complex-B-associated proteins (TTC30A and IFT52). We also generated a TtC29-mutated mouse model through the use of CRISPR-Cas9 technology. Remarkably, TtC29-mutated male mice also presented reduced sperm motility, abnormal flagellar ultrastructure, and male subfertility. Furthermore, intracytoplasmic sperm injections performed for TtC29-mutated mice and men harboring TTC29 mutations consistently acquired satisfactory outcomes. Collectively, our experimental observations in humans and mice suggest that bi-allelic mutations in TTC29, as an important genetic pathogeny, can induce MMAF-related asthenoteratospermia. Our study also provided effective guidance for clinical diagnosis and assisted reproduction treatments.