MITOVASC Institute, CNRS 6015, INSERM U1083, Angers University, Angers 49000, France.
Department of Reproductive Medicine, Angers University Hospital, Angers 49000, France.
Hum Reprod Update. 2021 Jun 22;27(4):697-719. doi: 10.1093/humupd/dmab001.
The best-known role of spermatozoa is to fertilize the oocyte and to transmit the paternal genome to offspring. These highly specialized cells have a unique structure consisting of all the elements absolutely necessary to each stage of fertilization and to embryonic development. Mature spermatozoa are made up of a head with the nucleus, a neck, and a flagellum that allows motility and that contains a midpiece with a mitochondrial helix. Mitochondria are central to cellular energy production but they also have various other functions. Although mitochondria are recognized as essential to spermatozoa, their exact pathophysiological role and their functioning are complex. Available literature relative to mitochondria in spermatozoa is dense and contradictory in some cases. Furthermore, mitochondria are only indirectly involved in cytoplasmic heredity as their DNA, the paternal mitochondrial DNA, is not transmitted to descendants.
This review aims to summarize available literature on mitochondria in spermatozoa, and, in particular, that with respect to humans, with the perspective of better understanding the anomalies that could be implicated in male infertility.
PubMed was used to search the MEDLINE database for peer-reviewed original articles and reviews pertaining to human spermatozoa and mitochondria. Searches were performed using keywords belonging to three groups: 'mitochondria' or 'mitochondrial DNA', 'spermatozoa' or 'sperm' and 'reactive oxygen species' or 'calcium' or 'apoptosis' or signaling pathways'. These keywords were combined with other relevant search phrases. References from these articles were used to obtain additional articles.
Mitochondria are central to the metabolism of spermatozoa and they are implicated in energy production, redox equilibrium and calcium regulation, as well as apoptotic pathways, all of which are necessary for flagellar motility, capacitation, acrosome reaction and gametic fusion. In numerous cases, alterations in one of the aforementioned functions could be linked to a decline in sperm quality and/or infertility. The link between the mitochondrial genome and the quality of spermatozoa appears to be more complex. Although the quantity of mtDNA, and the existence of large-scale deletions therein, are inversely correlated to sperm quality, the effects of mutations seem to be heterogeneous and particularly related to their pathogenicity.
The importance of the role of mitochondria in reproduction, and particularly in gamete quality, has recently emerged following numerous publications. Better understanding of male infertility is of great interest in the current context where a significant decline in sperm quality has been observed.
精子最广为人知的作用是使卵子受精，并将父本基因组传递给后代。这些高度特化的细胞具有独特的结构，包含受精和胚胎发育各阶段绝对必要的所有元素。成熟精子由头部（带有核）、颈部和鞭毛组成，鞭毛使精子能够运动，并包含中段（带有线粒体螺旋）。线粒体是细胞能量产生的核心，但它们也具有各种其他功能。尽管线粒体被认为对精子至关重要，但它们的确切病理生理学作用及其功能非常复杂。有关精子中线粒体的现有文献在某些情况下很密集且相互矛盾。此外，线粒体仅间接地参与细胞质遗传，因为其 DNA（父本线粒体 DNA）不会传递给后代。
本综述旨在总结有关精子中线粒体的现有文献，特别是关于人类的文献，以期更好地理解可能与男性不育有关的异常。
使用 PubMed 搜索 MEDLINE 数据库，查找与人类精子和线粒体相关的同行评审原始文章和综述。使用属于三个组的关键词进行搜索：“线粒体”或“线粒体 DNA”、“精子”或“精子”以及“活性氧”或“钙”或“凋亡”或信号通路。这些关键词与其他相关搜索短语结合使用。从这些文章的参考文献中获取了其他文章。
线粒体是精子代谢的核心，参与能量产生、氧化还原平衡和钙调节以及凋亡途径，所有这些都是鞭毛运动、获能、顶体反应和配子融合所必需的。在许多情况下，上述功能之一的改变可能与精子质量下降和/或不育有关。线粒体基因组与精子质量之间的联系似乎更加复杂。尽管线粒体 DNA 的数量及其存在的大规模缺失与精子质量呈负相关，但突变的影响似乎是异质的，特别是与它们的致病性有关。
线粒体在生殖，特别是配子质量中的作用的重要性在最近的大量出版物后才出现。在精子质量显著下降的当前背景下，更好地了解男性不育症具有重要意义。
