Autophagy and ubiquitin-mediated proteolysis may not be involved in the degradation of spermatozoon mitochondria in mouse and porcine early embryos
Autophagy and ubiquitin-mediated proteolysis may not be involved in the degradation of spermatozoon mitochondria in mouse and porcine early embryos
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DOI：
10.1017/s0967199414000689
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发表时间：
2016-02-01
期刊：
影响因子：
1.7
通讯作者：
Kim, Nam-Hyung
中科院分区：
文献类型：
--
作者：
Jin, Yong-Xun;Zheng, Zhong;Kim, Nam-Hyung
动物的线粒体基因组是母系遗传的，尽管父亲的线粒体在受精过程中进入卵母细胞。自噬和泛素介导的降解是秀丽隐杆线虫父系线粒体消除的原因；然而，这两个过程在哺乳动物父系线粒体降解中的作用尚不清楚。我们研究了轻链3 （LC3）和泛素在小鼠和猪胚胎着床前发育中的定位模式。我们发现LC3和泛素蛋白在受精后3小时定位于精子中部，在小鼠的4细胞期和猪胚胎的受精卵期，这两种蛋白都与父系线粒体共定位，并在受精后被移除。在小鼠桑葚胚期以后，存在零星的父系线粒体，且父系线粒体局限于4细胞胚胎的一个卵裂球。与阳性对照组相比，自噬抑制剂3-甲基腺嘌呤（3-MA）对父系线粒体的分布没有影响，而自噬诱导剂雷帕霉素（rapamycin）与对照组相比，加速了父系线粒体的去除。将完整的精子注入小鼠卵母细胞后，LC3和泛素定位于精子中部，但未降解的父系线粒体的残留物一直保留到囊胚期。我们的研究结果表明，父亲线粒体与自噬受体和泛素共定位，并在体外受精后被去除，但在卵浆内单精子注射（ICSI）后，精子线粒体鞘的一些残余可能会持续到桑葚胚期。
The mitochondrial genome is maternally inherited in animals, despite the fact that paternal mitochondria enter oocytes during fertilization. Autophagy and ubiquitin-mediated degradation are responsible for the elimination of paternal mitochondria in Caenorhabditis elegans; however, the involvement of these two processes in the degradation of paternal mitochondria in mammals is not well understood. We investigated the localization patterns of light chain 3 (LC3) and ubiquitin in mouse and porcine embryos during preimplantation development. We found that LC3 and ubiquitin localized to the spermatozoon midpiece at 3 h post-fertilization, and that both proteins were colocalized with paternal mitochondria and removed upon fertilization during the 4-cell stage in mouse and the zygote stage in porcine embryos. Sporadic paternal mitochondria were present beyond the morula stage in the mouse, and paternal mitochondria were restricted to one blastomere of 4-cell embryos. An autophagy inhibitor, 3-methyladenine (3-MA), did not affect the distribution of paternal mitochondria compared with the positive control, while an autophagy inducer, rapamycin, accelerated the removal of paternal mitochondria compared with the control. After the intracytoplasmic injection of intact spermatozoon into mouse oocytes, LC3 and ubiquitin localized to the spermatozoon midpiece, but remnants of undegraded paternal mitochondria were retained until the blastocyst stage. Our results show that paternal mitochondria colocalize with autophagy receptors and ubiquitin and are removed after in vitro fertilization, but some remnants of sperm mitochondrial sheath may persist up to morula stage after intracytoplasmic spermatozoon injection (ICSI).