| First Author | Hennigar SR | Year | 2015 |
| Journal | J Cell Physiol | Volume | 230 |
| Issue | 10 | Pages | 2345-50 |
| PubMed ID | 25808614 | Mgi Jnum | J:328827 |
| Mgi Id | MGI:6839106 | Doi | 10.1002/jcp.24992 |
| Citation | Hennigar SR, et al. (2015) TNFalpha Post-Translationally Targets ZnT2 to Accumulate Zinc in Lysosomes. J Cell Physiol 230(10):2345-50 |
| abstractText | Mammary epithelial cells undergo widespread lysosomal-mediated cell death (LCD) during early mammary gland involution. Recently, we demonstrated that tumor necrosis factor-alpha (TNFalpha), 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 TNFalpha retargets ZnT2 to lysosomes. We tested the hypothesis that TNFalpha 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 TNFalpha redistributed wild-type (WT) ZnT2 from late endosomes (Pearson's coefficient = 0.202 +/- 0.05 and 0.097 +/- 0.03; P<0.05) to lysosomes (0.292 +/- 0.03 and 0.649 +/- 0.03; P<0.0001), which increased lysosomal Zn (P<0.0001) and activated LCD (P<0.0001) compared to untreated cells. Mutation of the dileucine motif (L294V) eliminated the ability of TNFalpha to redistribute ZnT2 from late endosomes to lysosomes, increase lysosomal Zn, or activate LCD. Moreover, TNFalpha increased (P<0.05) AP-3 binding to wt ZnT2 but not to L294V immunoprecipitates. Finally, using phospho- and dephospho-mimetics of predicted phosphorylation sites (T281, T288, and S296), we found that dephosphorylated S296 was required to target ZnT2 to accumulate Zn in lysosomes and activate LCD. Our findings suggest that women with variation in the C-terminus of ZnT2 may be at risk for inadequate involution and breast disease due the inability to traffic ZnT2 to lysosomes. |
