精子形成におけるダイナミックなクロマチン変化の追跡

抄録

During the post-meiotic stage, male germ cells called spermatids undergo dynamic chromatin alterations. This is induced by histone-protamine exchange, in which more than 90% of histones are replaced by protamine in mature sperm, resulting in highly condensed sperm chromatin. In mice, spermatids are morphologically divided into 16 steps according to their differentiation state, while no method has been established to separate the spermatids at each step with high purity. Thus, it’s difficult to analyze the stepwise chromatin condensation quantitatively.

We previously generated a transgenic mouse line named “VC mouse” that carries two transgenes, H4-Venus (H4V) and H3.3-mCherry (H33C) in testicular germ cells. This mouse line allows us to separate the spermatids in different steps according to the expression level of H4V and H33C in combination with the cell size. By taking advantage of this property, we successfully isolated the spermatids at each step and subjected them to NGS analyses to track changes in chromatin dynamics and gene expression. We also apply the VC allele to various KO mouse analyses with defective sperm nuclei to compare their phenotypes regarding chromatin condensation level. My presentation will include examples of such use of the VC mouse.