A global view of the selectivity of zinc deprivation and excess on genes expressed in human THP-1 mononuclear cells

Abstract

Among the micronutrients required by humans, zinc has particularly divergent modes of action. cDNA microarray and quantitative PCR technologies were used to investigate the zinc responsiveness of known genes that influence zinc homeostasis and to identify, through global screening, genes that may relate to phenotypic outcomes of altered dietary zinc intake. Human monocytic͞ macrophage THP-1 cells were either acutely zinc depleted, using a cell-permeable zinc-specific chelator, or were supplemented with zinc to alter intracellular zinc concentrations. Initially, genes associated with zinc homeostasis were evaluated by quantitative PCR to establish ranges for fold changes in transcript abundance that might be expected with global screening. Zinc transporter-1 and zinc transporter-7 expression increased when cellular zinc increased, whereas Zip-2 expression, the most zinc-responsive gene examined, was markedly increased by zinc depletion. Microarrays composed of Ϸ22,000 elements were used to identify those genes responsive to either zinc depletion, zinc supplementation, or both conditions. Hierarchal clustering and ANOVA revealed that Ϸ5% or 1,045 genes were zinc responsive. Further sorting based on this pattern of the zinc responsiveness of these genes into seven groups revealed that 104 genes were linearly zinc responsive in a positive mode (i.e., increased expression as cellular zinc increases) and 86 genes that were linearly zinc responsive in a negative mode (i.e., decreased expression as cellular zinc increases). Expression of some genes was responsive to only zinc depletion or supplementation. Categorization by function revealed numerous genes needed for host defense were among those identified as zinc responsive, including cytokine receptors and genes associated with amplification of the Th1 immune response.nutrition ͉ genomics ͉ functional genomics ͉ immunology ͉ microarray

Zinc-stimulated Endocytosis Controls Activity of the Mouse ZIP1 and ZIP3 Zinc Uptake Transporters

“…In contrast to mZip4, little regulation of mZIP1 or mZIP3 mRNA levels by zinc status has been observed (19,22,24). These observations led us to investigate whether the activity of these proteins was regulated at a post-translational level.…”

“…In mammals, regulation of some zinc uptake transporters occurs at the level of mRNA abundance possibly via transcriptional control. For example, SLC39A2 (hZIP2) mRNA levels rise almost 30-fold in cultured THP-1 monocytes made zinc-deficient by treatment with TPEN, a membrane-permeable zinc chelator (22). Similarly, mice fed a zinc-deficient diet accumulate ϳ10-fold more mZIP4 mRNA in intestinal enterocytes than is found in zinc-replete animals (15).…”

“…In contrast to ZIP2 and ZIP4, expression of mammalian ZIP1 and ZIP3 is not highly regulated at the transcript level (19,22,24,25). This observation raised the question of how cells expressing these transporters regulate zinc uptake.…”

Nutrient-gene interactions: a single nutrient and hundreds of target genes

“…This suggests that MTF-1 controls the expression of many more important genes in addition to MT-I and MT-II Andrews et al, 2001). Very recently, MTF-2, an ortholog of MTF-1, was identified as another zinc-dependent transcription factor (Cousins et al, 2003). There appears to be a huge number of 'zinc-regulated' genes in all organisms and it remains to be determined how zinc availability in a cell controls target gene transcription directly or secondarily by indirect mechanisms (Beyersmann and Haase, 2001).…”

Development of Animal-free, Protein-Free and Chemically-Defined Media for NS0 Cell Culture

“…It was reported that zinc deprivation and excess affect gene expression in human THP-1 mononuclear cells (Cousins et al 2003). But it remained unclear how exactly and how much zinc ions replaced rHI functions in cell culture.…”