TNFα Post-Translationally Targets ZnT2 to Accumulate Zinc in Lysosomes

Mammary epithelial cells undergo widespread lysosomal‐mediated cell death (LCD) during early mammary gland involution. Recently, we demonstrated that tumor necrosis factor‐α (TNFα), a cytokine released during early involution, redistributes the zinc (Zn) transporter ZnT2 to accumulate Zn in lysosomes and activate LCD and involution. The objective of this study is to determine how TNFα retargets ZnT2 to lysosomes. We tested the hypothesis that TNFα signaling dephosphorylates ZnT2 to uncover a highly conserved dileucine motif (L294L) in the C‐terminus of ZnT2, allowing adaptor protein complex‐3 (AP‐3) to bind and traffic ZnT2 to lysosomes. Confocal micrographs showed that TNFα redistributed wild‐type (WT) ZnT2 from late endosomes (Pearson's coefficient = 0.202 ± 0.05 and 0.097 ± 0.03; P