A new ENU-induced mutant mouse with defective spermatogenesis caused by a nonsense mutation of the syntaxin 2/epimorphin (Stx2/Epim) gene.
A new ENU-induced mutant mouse with defective spermatogenesis caused by a nonsense mutation of the syntaxin 2/epimorphin (Stx2/Epim) gene.
复制标题
DOI：
10.1262/jrd.19186
复制
发表时间：
2008-04
期刊：
影响因子：
--
通讯作者：
K. Akiyama;Shiho Akimaru;Y. Asano;M. Khalaj;Chiyo Kiyosu;A. Masoudi;Sakino Takahashi;K. Katayama;T. Tsuji;J. Noguchi;T. Kunieda
中科院分区：
文献类型：
--
作者：
K. Akiyama;Shiho Akimaru;Y. Asano;M. Khalaj;Chiyo Kiyosu;A. Masoudi;Sakino Takahashi;K. Katayama;T. Tsuji;J. Noguchi;T. Kunieda
Repro34是一种由N-乙基-N-亚硝脲(ENU)诱导的突变，表现为精子发生缺陷引起的雄性不育小鼠。在本研究中，我们研究了repro34/repro34纯合子小鼠的发病机制和与精子发生有关的分子损伤。睾丸组织学检查显示，repro34/repro34小鼠的生精上皮含有精原细胞和精母细胞，但没有圆形和细长的精子细胞。代替这些单倍体细胞，多核巨细胞占据了生精小管的壁龛。Hsc70t是一种细长的精子细胞特异性蛋白，免疫组织化学染色证实没有细长的精子细胞。RT-PCR结果显示，精子细胞中特异表达的标记基因表达显著降低，而精母细胞特异性标记基因的表达无明显差异。这些发现表明，在从精母细胞到精子细胞的转变过程中，repro34/repro34小鼠的精子发生中断。已将repro34基因定位于小鼠5号染色体的7.0-Mb区域，该区域含有Synaxin 2/Epim基因，该基因的靶向干扰被报道为导致精子发生缺陷。因此，我们对Stx2/Epim基因的整个编码区进行了测序，并发现了导致该基因无义突变的核苷酸替代。Stx2/Epim基因在精子发生的第一波中的表达模式，在精子发生的后期增加，这与成体repro34/repro34睾丸中精子发生的影响阶段一致。因此，我们得出结论：repro34/repro34小鼠的雄性不育是由精母细胞向精子细胞转变过程中精子发生中断所致，而Stx2/Epim基因无义突变是导致精子发生中断的原因。
Repro34 is an N-ethyl-N-nitrosourea (ENU)-induced mutation in mice showing male-specific infertility caused by defective spermatogenesis. In the present study, we investigated pathogenesis and molecular lesions in relation to spermatogenesis in the repro34/repro34 homozygous mouse. Histological examination of the testis showed that the seminiferous epithelium of the repro34/repro34 mouse contained spermatogonia and spermatocytes but no round and elongating spermatids. Instead of these haploid cells, multinucleated giant cells occupied the niche of the seminiferous tubules. Immunohistochemical staining for Hsc70t, an elongating spermatid specific protein, confirmed the absence of elongating spermatids. Furthermore, RT-PCR showed that there were significantly reduced expressions of the marker genes specifically expressed in the spermatid and that there was no difference in the expressions of the spermatocyte specific marker genes. These findings indicated interruption of the spermatogenesis during transition from the spermatocyte to spermatid in the repro34/repro34 mouse. The repro34 locus has been mapped on a 7.0-Mb region of mouse chromosome 5 containing the Syntaxin 2/Epimorphin (Stx2/Epim) gene, and targeted disruption of this gene has been reported to cause defective spermatogenesis. We therefore sequenced the entire coding region of the Stx2/Epim gene and found a nucleotide substitution that results in a nonsense mutation of this gene. The expression pattern of the Stx2/Epim gene during the first wave of spermatogenesis, increased expression at later stages of spermatogenesis, was in agreement with the affected phase of spermatogenesis in the adult repro34/repro34 testis. We therefore concluded that the male infertility of the repro34/repro34 mouse is caused by the interruption of spermatogenesis during transition from the spermatocyte to spermatid and that the nonsense mutation of the Stx2/Epim gene is responsible for the interruption of spermatogenesis.