FIGURE 1.

ZnT2 was required for PRL-stimulated acute zinc secretion in MECs. Cells expressing endogenous levels of ZnT2 (A), cells overexpressing ZnT2 (B), or ZnT2-attenuated cells (C) were preincubated in serum-free medium containing 1.0 μm ZnSO₄ and 0.1 μCi of ⁶⁵Zn for 3 h. Medium was replaced with serum-free medium containing diethylenetriamine pentaacetic acid (50 μm) with or without PRL, and ⁶⁵Zn was measured for up to 8 h. Values represent mean pmol of zinc/μg of protein ± S.D. (n = 4 samples/time point). Analysis of AUC indicates a significant difference of PRL treatment in cells expressing endogenous levels of ZnT2 (A) and overexpressing ZnT2 (B), p < 0.05. No effect of PRL in ZnT2-attenuated cells was detected (NS). Experiments were repeated three times. D, cells were transfected with thymidine kinase promoter-linked Renilla luciferase vector (internal control) and 4×MRE-pGL3 and either pGL3 empty vector (EV), scrambled siRNA (Mock), or ZnT2 siRNA. Luminescence was measured as an index of changes in cytoplasmic zinc pools. Data represent mean luminescence ± S.D. (error bars) (n = 4 samples/time point). *, significant effect of ZnT2KD on luciferase activity, p < 0.05. Experiments were repeated two times.