Fig. 4
OXR1 modulates PRMT-induced epigenetic histone modifications during neurogenesis. a Proximity ligation assay showing the interaction of OXR1 with PRMT1 (magenta spots) and PRMT5 (green spots) in patient fibroblasts (OXR1ΔEx18) and control cells (CTRL). Nuclei were indicated by DAPI staining. b The Western blot analysis showing histone arginine modifications in induced pluripotent stem cells (iPSC) and neural stem cells (NSC). The arginine modification marks include H3R2me2s, H3R2me2a, H3R17me2a, H4R3me2a, H4R3me2s, H3R17me2s, H3R26me2s, and lysine marks H3K4me3, H3K27me3, and H3K9me3; Histone 3 was used as loading control. c Overlay DEGs and putative targets of selected histone modifications in the published CHIPseq database. A representation factor (R) > 1 indicates more overlap than expected of two independent groups and a R < 1 indicates less overlap than expected. R = 1 indicates that the two groups by the number of genes expected for independent groups of genes. Probability (p) is indicated. Calculated by http://nemates.org/MA/progs/overlap_stats.cgi. d In vitro methyltransferase assay showing a direct role of OXR1 in regulating the enzymatic activity of PRMT5. N-terminal H4 peptides (1-21aa) and the mutant ones H4-R3K (1-21aa) were used as substrates. Different molar ratio of PRMT5/MEP50 protein complex (calculated as tetramer) to the full length OXR1A or truncated ones, such as 4:1 ( +), 1:1(+ +), and 1:4(+ + +), was applied in each reaction. The enzymatic activity of PRMT5 was shown by the CPM (Count per minute) value of 3H-Methyl incorporation. All Data are shown as mean ± SD, *p < 0.05, ***p < 0.001, Student’s t test