Muratori Monica, Marchiani Sara, Criscuoli Luciana, Fuzzi Beatrice, Tamburino Lara, Dabizzi Sara, Pucci Chiara, Evangelisti Paolo, Forti Gianni, Noci Ivo, Baldi Elisabetta
Department of Clinical Physiopathology, Andrology Unit,, University of Florence, viale Pieraccini 6, 1-50139 Florence, Italy.
Soc Reprod Fertil Suppl. 2007;63:153-8.
The ubiquitin-proteasome is an ubiquitous system mainly devoted to protein degradation. The presence of ubiquitinated proteins in male gametes suggests a role for this system also in reproduction. Available evidence indicate that ubiquitin in spermatozoa may have a role in semen quality control, as ubiquitinated defective spermatozoa in the epididymis are subsequently phagocytosed by epididymal epithelial cells. Moreover, a role both in the regulation of mitochondrial inheritance in mammals (paternal mitochondria are eliminated and their ubiquitination appears to be important for this process) and in sperm-oocyte interaction at fertilization (which is inhibited by an inhibitor of proteasome) have been also suggested. We found that both morphologically normal and abnormal human spermatozoa in semen may be ubiquitinated and that the percentage of ubiquitinated sperm in the ejaculate positively correlates with normal morphology and motility, suggesting that sperm ubiquitination may have a positive role in sperm functions. It remains to be defined if and which patterns of ubiquitination of spermatozoa may distinguish between the different biological functions of this system. In an attempt to answer this question, we set up a method to detect simultaneously ubiquitination and DNA fragmentation by FACScan since the latter parameter is related to a poor quality of semen; in particular, abnormal morphology. We found that DNA fragmented human spermatozoa are also ubiquitinated. Studies are in progress to determine the correlation between the fraction of ubiquitinated-non DNA fragmented spermatozoa and parameters of semen analysis.
泛素 - 蛋白酶体是一个普遍存在的系统，主要负责蛋白质降解。雄性配子中泛素化蛋白质的存在表明该系统在生殖过程中也发挥作用。现有证据表明，精子中的泛素可能在精液质量控制中发挥作用，因为附睾中泛素化的缺陷精子随后会被附睾上皮细胞吞噬。此外，还提出了其在哺乳动物线粒体遗传调控（父本线粒体被清除，其泛素化对此过程似乎很重要）以及受精时精子 - 卵母细胞相互作用（被蛋白酶体抑制剂抑制）中的作用。我们发现精液中形态正常和异常的人类精子都可能被泛素化，并且射精中泛素化精子的百分比与正常形态和活力呈正相关，这表明精子泛素化可能对精子功能具有积极作用。精子泛素化的何种模式以及是否能够区分该系统的不同生物学功能仍有待确定。为了回答这个问题，我们建立了一种通过流式细胞仪同时检测泛素化和DNA片段化的方法，因为后一个参数与精液质量差有关，特别是与异常形态有关。我们发现DNA片段化的人类精子也会被泛素化。目前正在进行研究以确定泛素化 - 非DNA片段化精子的比例与精液分析参数之间的相关性。
