Fig. 2: MEA1 is required for AP1-dependent cargo trafficking and termination of STING signaling.

a Diagram illustrating AP1-dependent transport of constitutive and signal-induced cargoes such as FOLR1 and STING from the TGN to endolysosomal compartments. Impairment of AP1 function results in aberrant accumulation of FOLR1 on the cell surface and reduced termination of STING signaling. b Representative immunoblots from three independent experiments showing the expression of the indicated proteins in WT and MEA1 KO HeLa cells. c Normalized surface levels of FOLR1 measured using flow cytometry. Data normalization was performed by setting the mean value of WT data points as 1 and all data points were normalized to that mean value. Data are presented as mean ± SD of three biological replicates. ***P < 0.001 (one-way ANOVA). d Representative immunoblots showing the total levels of the indicated proteins in WT or KO RPE1 cells, a non-transformed human cell line with a near-diploid genome⁶⁵. Cells were treated with diABZI for two hours before harvest. e Quantification of immunoblot data, including those shown in (d). Data normalization was performed by setting the mean value of AP1G1 KO data points as 100% and all data points, including AP1G1 KO ones were normalized to that mean value. Data are presented as mean ± SD of three biological replicates. ***P < 0.001 (one-way ANOVA). f Representative immunoblots showing the levels of the indicated proteins in CCVs isolated from WT or KO RPE1 cells. Cells were cultured and stimulated as in (d). g Quantification of immunoblot data, including those shown in (f). Data normalization was performed by setting the mean value of WT data points as 100% and all data points including WT ones were normalized to that mean value. Data are presented as mean ± SD of three biological replicates. ***P < 0.001 (one-way ANOVA).