Fig. 5: The SPOCD1–SPIN1 interaction is required for the de novo DNA methylation of young LINE1 elements.

a,b, Representative testis sections of n = 3 wild-type, Spocd1^ΔSPIN and Spocd1^−/− mice stained red for the LINE1 ORF1p (a) or IAP GAG protein (b). DNA was stained with DAPI (blue). Scale bars, 100 μm. c, RNA-seq heat maps showing fold changes in expression relative to wild type for the ten most upregulated LINE1 and ERVK transposable elements in Spocd1^−/− P20 testes (n = 3 from each genotype). ***P < 0.001 of Bonferroni-corrected two-sided Wald’s test assuming n-binominal distribution. Only significant differences (P < 0.05) are shown. d–g, Genomic CpG methylation analysis of P14 undifferentiated spermatogonia from wild-type (n = 6), Spocd1^ΔSPIN (n = 4) and Spocd1^−/− mice (n = 3). d,e, Percentages of CpG methylation levels of the indicated genomic features (with genic, promoter and CpG island (CGI) regions defined as those not overlapping transposable elements, and intergenic regions as those not overlapping transposable elements or genes) or transposable elements (not overlapping genes) are shown as box plots. Boxes represent interquartile range from the 25th to the 75th percentile, the horizontal line shows the median, and whiskers show the data range of the median ± twice the interquartile range. Significant differences (P < 0.05 of Bonferroni-corrected two-tailed Student’s t-tests) of Spocd1^ΔSPIN (n = 4) and Spocd1^−/− (n = 3) samples to wild-type (n = 6) are indicated. f, Metaplots of mean CpG methylation over the indicated transposable element. *P = 0.05–0.01, **P = 0.01–0.001 and ***P < 0.001 for Bonferroni-corrected two-tailed Student’s t-tests comparing the average CpG methylation of the promoter region to wild type for Spocd1^ΔSPIN1 (red) and Spocd1^−/− (blue). Only significant differences (P < 0.05) are shown. g, Correlation analysis of mean CpG methylation loss relative to the wild type for individual transposable elements of the indicated LINE1 and ERVK families in relation to their divergence from the consensus sequence in Spocd1^ΔSPIN spermatogonia.