Distinct H3K9me3 And DNA Methylation Modifications During Mouse Spermatogenesis

Spermatogenesis is a highly complex and orderly process.Spermatogonial stem cells(SSC)are located in the basement of seminiferous tubules,which can finally produce mature sperm that stored in epididymis by a series of differentiation,meiosis and deformation events.We hope to reveal the physiological regulation of male reproduction and provide theoretical basis for solving practical production problems such as male sterility,by in-depth understanding of the development mechanism in different spermatogenic cells stages.The article take advantage of undifferentiated spermatogonia cells,differentiated spermatogonia,pachytene spermatocytes and spermatids obtained by fluorescence-activated cell sorting and combined ultra-low-input micrococcal nuclear-based native Ch IP-seq and whole Genome Bisulfite Sequencing analysis,which establish the whole genome DNA methylation and H3K9me3 dynamic modification profile during spermatogenesis.The main results were as follows:1.DNA methylation and H3K9me3 modification have different sequence preference and dynamic distribution on the promoter and repeats.The coverage of H3K9me3 decreased gradually with the progress of spermatogenesis.The coverage of H3K9me3 on the promoter region reached the highest level in the round spermatids,however,on the repeats decreased gradually.H3K9me3 modification on the repeats was highly enriched,while on the promoters was highly enriched on the round spermatid.2.Through K-means clustering analysis of H3K9me3 modification during spermatogenesis,we found that specific H3K9me3 modification in undifferentiated and differentiated spermatogonia cells was mainly enriched in the repeats,while the DNA methylation modification was not fully established.Specific H3K9me3 modification was enriched in the gene promoter regions during meiosis and spermatogenesis.There is no obvious preference in mature sperm.3.DNA methylation corresponding to the specific H3K9me3 modification domain in undifferentiated and differentiated spermatogonia cells was still increasing before meiosis,while H3K9me3 modification was decreasing in this process,repeats expression of the two inhibitory epigenetic modifications were activated during the pachytene spermatocytes.4.H3K9me3 modification of specific gene promoter regions is highly enriched in pachytene spermatocyte stage,and low enriched in the round spermatids.H3K9me3 modification in the promoter region of this gene was decreased during the round spermatids compared with pachytene spermatocytes.4.There are specially expressed genes,such as Hypm and Cypt1 genes in the round spermatid.H3K9me3 modification in the promoter region of these genes is erased in the round spermatid stage compared with pachytene spermatocytes.5.During the transformation of spermatogonia stem cells into differentiated spermatogonia cells,DNA methylation in the paternal imprinted control regions was rapidly established,while DNA methylation in the maternal imprinted control regions was rapidly erased.H3K9me3 modification in the paternal imprinting regulation region was gradually erased.In general,the article has established the DNA methylation and H3K9me3 modification during spermatogenesis,which provides preconditions for further understanding of the mechanism of spermatogenesis.