Influence of parenteral zinc and actinomycin D on tissue zinc uptake and the synthesis of a zinc-binding protein

Abstract

Parenterally administered zinc markedly increased the incorporation of 14C-cystine and 65Zn into a low molecular weight zinc binding protein (ZnBP) isolated from liver cytoplasm of rats fed an adequate amount of zinc. This zinc load significantly increased the zinc content in the liver. The increase in hepatic zinc content was inhibited by actinomycin D indicating that DNA-dependent RNA synthesis is required for zinc uptake into liver. Antinomycin D also produced a concomitant decrease in ZnBP synthesis indicating that this protein may be involved in the uptake mechanism in cells. Zinc repletion also stimulated the synthesis of hepatic ZnBP in zinc deficient rats. This stimulation was also prevented by prior administration of actinomycin D. A similar effect was observed in the intestinal mucosal cells. The data collectively indicate that the control of the synthesis of ZnBP which occurs at the transcriptional level of protein synthesis is responsive to zinc status and thus may have a function in zinc metabolism.