Chhikara Nirmal, Tomar Anil Kumar, Datta Sudip Kumar, Yadav Savita
Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India.
Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi, India.
Andrology. 2023 Jan;11(1):73-85. doi: 10.1111/andr.13289. Epub 2022 Sep 13.
The cellular and molecular mechanisms of the events that help spermatozoa acquire their fertilizing capability during capacitation and acrosome reaction are not completely understood.
This study was performed with a postulation that the identification of sperm proteins and their changes during in vitro capacitation and acrosome reaction will unravel unknown molecular aspects of fertilization that impact male fertility.
Spermatozoa collected from sequential conditions, that is, separation of ejaculated spermatozoa by Percoll gradient centrifugation, in vitro capacitation, and acrosome reaction were processed for tandem mass spectrometric analysis, followed by protein identification, label-free quantitation, and statistical analysis.
Collectively, a total of 1088 sperm proteins were identified. In comparison to ejaculated spermatozoa, 44 and 141 proteins were differentially expressed in capacitated and acrosome reacted spermatozoa, respectively. A large number of proteins were found downregulated, including clusterin, pyruvate dehydrogenase E1 component, semenogelin-1 and 2, heat shock protein 90, beta-microseminoprotein, and keratin. It was expected as sperm-membrane-associated proteins are removed during capacitation. There were significant proteomic alterations in asthenozoospermia compared to normozoospermia; however, variation was more noticeable among proteins of acrosome reacted spermatozoa and those released during the acrosome reaction. The processes enriched among downregulated proteins in asthenozoospermia included acrosome assembly, binding of spermatozoa to zona pellucida, nucleosome assembly, flagellated sperm motility, protein folding, oxidative phosphorylation, tricarboxylic acid cycle, chromatin silencing, gluconeogenesis, glycolytic process, and glycolysis.
The dynamic information generated about proteomic alterations in spermatozoa during capacitation and acrosome reaction and their variability in asthenozoospermia will contribute not only to enhancing our understanding of processes that prepare spermatozoa to acquire fertilization capability but also help in deciphering novel factors of male infertility.
精子在获能和顶体反应过程中获得受精能力的细胞和分子机制尚未完全明确。
本研究基于这样一种假设，即鉴定精子蛋白质及其在体外获能和顶体反应过程中的变化，将揭示影响男性生育能力的受精过程中未知的分子层面。
对从连续条件下收集的精子进行处理，即通过Percoll梯度离心法分离射出的精子、体外获能和顶体反应，然后进行串联质谱分析，接着进行蛋白质鉴定、无标记定量和统计分析。
总共鉴定出1088种精子蛋白质。与射出的精子相比，分别有44种和141种蛋白质在获能精子和顶体反应精子中差异表达。发现大量蛋白质表达下调，包括簇集素、丙酮酸脱氢酶E1组分、精液蛋白-1和-2、热休克蛋白90、β-微精蛋白和角蛋白。这是预期的，因为精子膜相关蛋白在获能过程中会被去除。与正常精子症相比，弱精子症存在显著的蛋白质组学改变；然而，顶体反应精子和顶体反应过程中释放的精子的蛋白质之间的差异更为明显。弱精子症中下调蛋白质所富集的过程包括顶体组装、精子与透明带结合、核小体组装、有鞭毛精子运动、蛋白质折叠、氧化磷酸化、三羧酸循环、染色质沉默、糖异生、糖酵解过程和糖酵解。
关于精子在获能和顶体反应过程中蛋白质组学改变及其在弱精子症中的变异性所产生的动态信息，不仅将有助于增进我们对使精子获得受精能力的过程的理解，还将有助于解读男性不育的新因素。
