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. 2019 Jan 24;116(8):2987–2995. doi: 10.1073/pnas.1820161116

Fig. 2.

Fig. 2.

Wnt-induced endocytosis and lysosomal activity require methionine and PRMT1. (A–D) Methionine depletion inhibited PRMT1 sequestration into GSK3-containing vesicles by Wnt3a treatment in in situ protease protection analyses (compare B to D). (E) PRMT1 and GSK3 colocalization in vesicles quantified by Pearson’s correlation coefficient using ImageJ. (F–H) Methionine depletion decreased Wnt-induced endolysosomal activity, assessed by the endocytosis and digestion of BSA-DQ. (I–K) PRMT1 depletion with siRNA (siPRMT1) decreased Wnt3a-induced lysosomal activity compared with siScrambled control (siCtr) cells (compare J to K), as assessed by endocytosis of BSA-DQ. (L) Diagram of the BSA-DQ assay, which is endocytosed and fluoresces only after the protein is digested in lysosomes. (M) Lysosomal activity quantification of BSA-DQ fluorescence per cell after 30 min of methionine depletion. (N) Wnt-induced degradation of BSA-DQ in lysosomes requires the PRMT1 enzyme (ImageJ quantification per cell). (Scale bars: 10 μm.) **P < 0.01; n < 4.