Extended Data Fig. 1: The dependency of METTL16 in human cancers and its preferential localization in cytoplasm.
From: METTL16 exerts an m6A-independent function to facilitate translation and tumorigenesis
a, CERES scores of a set of METTL family members from genome-scale CRISPR–Cas9 essentiality screens across 769 human cancer cell lines. The raw data were downloaded from DepMap (https://depmap.org/portal/). As the CERES scores, 0 and -1 represent the median effects of nonessential genes and common core essential genes, respectively. The lower CERES score indicates the higher cancer dependency of the specific gene. For each violin, the minimum, first quartile, median, third quartile, and maximum were displayed. The average of CERES scores for each METTL family member was shown. b, METTL16 was also detected by another genome-scale CRISPR–Cas9 screen with 324 cancer cell lines as a common essential gene in majority of human cancer cell lines in all 13 cancer types. The raw data were derived from https://score.depmap.sanger.ac.uk/. In this screen, 324 cancer cell lines from 13 cancer types were included. MYC and BRD4 were shown as positive controls, which represent the appealing cancer therapeutic targets. The number of cells with loss-of-fitness effects and the number of cancer types were highlighted for each gene. For example, METTL16 (211/13) indicates that knockout (KO) of METTL16 exhibits loss-of-fitness effects (essential function) in 211 of the 324 cancer cell lines and the 211 cancer cell lines cover all the 13 cancer types. c, Subcellular localization of endogenous METTL3, METTL14, and METTL16 in Huh7 cells as determined by immunofluorescence. SC35 worked as a nuclear speckle marker. In line with the trend in HEK293T cells, a much higher percentage of METTL16 is located in the cytoplasm than METTL3 and METTL14. Data shown represent 3 independent experiments. d, Pearson correlation coefficients showing the extent of colocalization of the three METTL family members with nuclear (DAPI) in Huh7 cells. The Pearson correlation coefficients were determined by the ZEN software. Again, both METTL3 and METTL14, but not METTL16, are predominantly localized in nuclear. Data are mean ± s.e.m. Statistics: unpaired, two-tailed t-test. n = 6 independent experiments. e, f, Western blotting showing the overexpression efficacy of wild type (WT) METTL16 and its three mutants, and their subcellular distributions in HEK293T (e) and HepG2 (f) cells. Here, F187G and PP185/186AA represent loss-of-function mutation of METTL16 methyltransferase activity, while R200Q represents a gain-of-function mutation. 3 × Flag was infused to the N-terminal of WT or mutant METTL16. GAPDH and α-Tubulin were used as loading control of total protein and cytoplasmic protein samples, and H3K9me3 was selected as loading control of nuclear protein.
