Fig 2: PRMT1, PRMT5 and CARM1 expression in five Hodgkin's lymphoma (HL) cell lines. Western blot showing PRMT expression in HL cell lines compared to GC B cells. MCM7 was used as a loading control.

Fig 3: Model of the effects of the growth factor Wnt in receptor-mediated endocytosis (micropinocytosis) and in receptor-independent endocytosis of proteins from extracellular fluids (macropinocytosis). The Wnt coreceptors Lrp6 and Fz are incorporated into receptor-mediated small microendocytic vesicles, triggering an as yet unknown signal that causes actin cytoskeleton remodeling in the lamellipodium at the leading edge of the cell, forming membrane ruffles and macropinocytic cups that engulf large amounts of the surrounding liquid. Both types of endosomes fuse into common MVBs/late endosomes that contain GSK3 and PRMT1 and require the ESCRT machinery for their formation. In the presence of Wnt, BSA incorporated by macropinocytosis is channeled to degradation in lysosomes, providing a source of nutrition for cells in which Wnt signaling is activated. The recycling of membrane from macropinocytic vesicles may help drive the considerable increase in microautophagy observed in MVBs/late endosomes shortly after Wnt treatment (8).

Fig 4: SAM addition to the culture medium rescues inhibition of Wnt signaling. (A–L) Methionine depletion decreased Wnt-induced vesicle formation and inhibited the Wnt-induced sequestration of PRMT1 and GSK3 after 30 min of Wnt3a treatment, and this effect was rescued by the addition of 1 mM SAM to the culture medium. (M) Quantification of the rescue of PRMT1 and GSK3 protease protection in vesicles by Pearson’s correlation coefficient. (N) Addition of 1 mM SAM increased Wnt-induced BAR luciferase activity when methionine was depleted. (O) Schematic depiction of the effect of addition of nicotinamide (vitamin B3) to the culture medium. Nicotinamide becomes readily methylated (generating 1-methylnicotinamide) and serves as a sink to store methyl groups and decrease SAM levels (59, 60). (P) Addition of 8 mM nicotinamide to the culture medium inhibited BAR/β-catenin luciferase activity. (Scale bars: 10 μm.) **P < 0.01; n < 3.

Fig 5: (A and B) PRMT1, PRMT5, CARM1 and PADI4 expression in GC B cells and EBV infected GC B cells. (A) Q-RT PCR showing PRMT and PADI4 expression. Grey bars represent expression in GC B cells isolated from three different patients (1,2,3) and black bars that in each of the corresponding EBV infected GC B cells. The GC B cells with the highest expression of the gene in question served as the reference sample. Assays were carried out in triplicate and results are presented as 2−∆∆CT values; (B) Western blot showing PRMT expression in GC B cells and in corresponding EBV infected GC B cells; MCM7 was used as a loading control.