Fig. 4: Serine uptake is mediated by SLC38A1.

a The expression profile of serine metabolism-related genes in MKs cultured with vehicle or excessive serine. b Schematics of serine metabolism. c Assessment of mRNA expression of serine transporters in differentiated cells treated with vehicle or excessive serine at day 12 (mean ± SD, n = 3 independent experiments). Significance was analyzed with an One-way ANOVA followed by Dunnett’s multiple comparison test. d Protein levels of SLC1A4, SLC1A5 and SLC38A1 were detected with immunoblotting in differentiated cells treated with vehicle or serine at day 12. n = 3 independent experiments. e The mRNA levels of SLC38A1 in CD34⁺ cells containing control and SLC38A1 shRNAs as detected with qPCR analysis (mean ± SD, n = 3 independent experiments). f Protein levels of SLC38A1 were detected with immunoblotting in CD34⁺ cells infected with lentivirus-containing scramble or SLC38A1-shRNA. n = 3 independent experiments. g The concentration of extracellular serine in CD34⁺ cells containing control and SLC38A1 shRNAs (mean ± SD, n = 3 independent experiments). h Flow cytometry analysis of the percentage of CD41a⁺CD42b⁺ MKs from CD34⁺ cells with SLC38A1 knockdown exposed to serine (mean ± SD, n = 3 independent experiments). i Representative images of proplatelet formation from MKs from CD34⁺ cells with SLC38A1 knockdown exposed to vehicle or serine. The scale bar is 20 µm. j Generation of CD41a⁺CD42b⁺ PLPs at day 12 from CD34⁺ cells with SLC38A1 knockdown exposed to vehicle or serine (mean ± SD, n = 3 independent experiments). Results represent means ± SD. An unpaired two-sided Student’s t-test was used in e, g, h, j. Source data are provided as a Source Data file.