Whole genome DNA methylation of undifferentiated spermatogonia of postnatal day 14 (P14) wild-type and Spocd1-K464A (does not interact with TPR) homozygous mutant mice
In the male mouse germline, PIWI-interacting RNAs (piRNAs), bound by the PIWI protein MIWI2 (PIWIL4), guide the DNA methylation of young active transposable elements (TEs) through SPOCD1. We find that SPOCD1 interacts with the nuclear pore protein TPR, and that this interaction is required to prevent SPOCD1 and its known binding partners SPIN1 and C19ORF84 from being incorporated into constitutive heterochromatin. We perform enzymatic methylation sequencing of undifferentiated spermatogonia from wild-type mice and mice carrying the K464A mutation in SPOCD1, which prevents interaction with TPR. The mutant mice display a stochastic failure of young LINE1 methylation.