Proteomics Research Of Posttranslational Modification Of Human Sperm Histone

The spermatogenesis is a highly regulated process, and the existing researches have shown that the posttranslational modification has been involved in the regulation of many important events in the process of spermatogenesis. One of the important research directions of posttranslational modification is the histone modification. The N/C end of histone is rich in amino acid residues which can be covalently modified, and it can have many modifications such as acetylation, phosphorylation, methylation and ubiquitin, etc. It has been reported that at least 11 kinds of posttranslational modifications exist in the histone of more than 60 different amino acid residues. These posttranslational modifications can change the structure of chromosome, and cause transcription activation or inhibition in the genes. In addition, during the process of spermiogenesis to form mature sperm, the protamine and histone replacement occurs, and the genetic materials of sperms will be passed on stably with protamine, but it has been found that the sperm residual histones can be passed to the descendant embryo to function as epigenetic information. Therefore, to clarify the histone modification of sperm can help clarify the epigenetic information of the male passed to the descendants through sperm. This research aims to identify the specific posttranslational modification composition and sites of the histones of human mature sperm through the proteomic technology, and then make a preliminary discussion on the functions of the modified mediation.In the earlier studies, our lab established the relatively mature proteomics platform using advanced Orbitrap mass spectrometer, and successfully built the human sperm proteome. In the proteome, it was found that sperm have a complex protein composition. In order to identify the posttranslational modifications of human sperm histones, in this research, we optimized the human sperm histone extraction and enrichment method. We obtained the human sperm histone by acid extraction and chemical acylation methods, then further used the liquid chromatography-tandem mass spectrometry for identification after trypsin digestion, and obtained 261 histone modification sites in human sperm in total, corresponding to 43 histones (including various subtypes). Among them, there were 91 sites in acetylation modification,9 sites in double methylation modification,148 sites in lysine formyl modification,86 sites in methylation modification,3 sites in tyrosine oxidation modification and 94 sites in lysine trimethylation modification. The bioinformatic analysis showed that these modified histones had been widely involved in cell proliferation and regulation, chromatin remodeling, gene silencing, transcriptional regulation and many other biological events.In conclusion, the human sperm histone has very complex posttranslational modifications. This research systematically identified posttranslational modifications of human sperm histones, and obtained a large amount of new modification sites, thus laying important basis for clarifying the role of epigenetic information of human sperm histone modification in the embryonic development process.