DNA Methylation and Histone Modifications Associated with Male Germ Cell Differentiation

Spermatogenesis is a highly regulated process in which undifferentiated spermatogonial stem cells differentiate to form highly specialized sperm cells capable of fusing with the ovum to form a zygote. This is achieved through tightly controlled regulation of gene expression which depends crucially on DNA accessibility. DNA accessibility is largely dependent on epigenetic modifications including DNA methylation and modifications of the histones. DNA methylation is catalysed by DNA methyltransferase (DNMT) enzymes. The spatial and temporal expression levels and functional features of the DNMTs are thought to landscape the gene expression in the male germ cells. On the other hand, the histone code is defined by an array of molecules that bring about post-translational modifications of various histones at various sites. All these intricate events orchestrate germ cell specification, stem cell maintenance, mitotic amplification, initiation of meiosis and post-meiotic differentiation events. This review summarizes the sequential changes in DNA methylation and the histone modification profiles in germ cells leading to the production of functional spermatozoa.