TY - JOUR
T1 - Prolactin (PRL)-stimulated ubiquitination of ZnT2 mediates a transient increase in zinc secretion followed by ZnT2 degradation in mammary epithelial cells
AU - Seo, Young Ah
AU - Lee, Sooyeon
AU - Hennigar, Stephen R.
AU - Kelleher, Shannon L.
PY - 2014
Y1 - 2014
N2 - The zinc transporter ZnT2 imports zinc into secretory vesicles and regulates zinc export from the mammary epithelial cell. Mutations in ZnT2 substantially impair zinc secretion into milk. The lactogenic hormone prolactin (PRL) transcriptionally increases ZnT2 expression through the Jak2/STAT5 signaling pathway, increasing zinc accumulation in secretory vesicles and zinc secretion. Herein, we report that PRL post-translationally stimulated ZnT2 ubiquitination, which altered ZnT2 trafficking and augmented vesicular zinc accumulation and secretion from mammary epithelial cells in a transient manner. Ubiquitination then down-regulated zinc secretion by stimulating degradation of ZnT2. Mutagenesis of two N-terminal lysine residues (K4R and K6R) inhibited ZnT2 ubiquitination, vesicular zinc accumulation and secretion, and protein degradation. These findings establish that PRL post-translationally regulates ZnT2-mediated zinc secretion in a multifactorial manner, first by enhancing zinc accumulation in vesicles to transiently enhance zinc secretion and then by activating ubiquitin-dependentZnT2 degradation. This provides insight into novel mechanisms through which ZnT2 and zinc transport is tightly regulated in mammary epithelial cells.
AB - The zinc transporter ZnT2 imports zinc into secretory vesicles and regulates zinc export from the mammary epithelial cell. Mutations in ZnT2 substantially impair zinc secretion into milk. The lactogenic hormone prolactin (PRL) transcriptionally increases ZnT2 expression through the Jak2/STAT5 signaling pathway, increasing zinc accumulation in secretory vesicles and zinc secretion. Herein, we report that PRL post-translationally stimulated ZnT2 ubiquitination, which altered ZnT2 trafficking and augmented vesicular zinc accumulation and secretion from mammary epithelial cells in a transient manner. Ubiquitination then down-regulated zinc secretion by stimulating degradation of ZnT2. Mutagenesis of two N-terminal lysine residues (K4R and K6R) inhibited ZnT2 ubiquitination, vesicular zinc accumulation and secretion, and protein degradation. These findings establish that PRL post-translationally regulates ZnT2-mediated zinc secretion in a multifactorial manner, first by enhancing zinc accumulation in vesicles to transiently enhance zinc secretion and then by activating ubiquitin-dependentZnT2 degradation. This provides insight into novel mechanisms through which ZnT2 and zinc transport is tightly regulated in mammary epithelial cells.
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U2 - 10.1074/jbc.M113.531145
DO - 10.1074/jbc.M113.531145
M3 - Article
C2 - 25016022
AN - SCOPUS:84906572321
SN - 0021-9258
VL - 289
SP - 23653
EP - 23661
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 34
ER -