Table 1.
Data extracted from 15 studies investigating the effect of zinc level on gene-specific or global DNA methylation in humans and rodents.
| Autor and Reference | Country | Subjects/Sample size | DNA Methylation Method | Biological samples | Targeted genes | Zinc measurement method/related tissues | Zinc level | Methylation status | Consequences |
|---|---|---|---|---|---|---|---|---|---|
| Kumar, (2015) [12] | Australia | Two breastfed human neonates (1. premature at 36 weeks, 2. premature at 37 weeks) | Pyrosequencing | Fibroblast and lymphoblast cells | SLC30A5, SLC30A6 | N.A/Venous blood and milk | Zinc deficiency | Methylation of SLC30A5 was reduced in lymphoblasts but increased in fibroblasts | Reduced levels of SLC30A5 mRNA and protein in lymphoblasts were associated with a reduction of zinc in breast milk |
| Perng, (2014) [20] | USA | 987 adults aged 45–84 years | Pyrosequencing | Blood | LINE-1 and Alu | FFQ/N.A | Zinc supplementation | Increase Alu methylation but not effect on LINE-1 | Elevation of LINE-1 methylation found in subjects with higher BMI, positive correlation between height and Alu methylation |
| Iqbal, (2019) [21] | Bangladesh | 324 children aged 2–3 years | 5-mC DNA ELISA | Blood | Global DNA | Semiquantitative FFQ/N.A | Low level of zinc in the diet | Significantly increase in global DNA methylation | Positive correlation between lower zinc intake by children and the prevalence of stunting |
| Vidal, (2015) [13] | USA | 319 infant-mother pairs | Pyrosequencing | Venous and umbilical cord blood | PEG3, PLAGL1, DMRs and MEG3 DMRs. | Solution-based ICP-MS/Venous blood | Low and higher zinc concentrations | Lower zinc and a high level of Cd reduced PLAGL1 methylation, higher zinc increased PEG3 methylation but no association with MEG3 methylation in offspring | Maternal Cd exposure in early pregnancy alters DNA methylation at multiple DMRs in offspring with sex and possibly race/ethnic-specific effects, and Zn may mitigate these effects. |
| Perng, (2012) [22] | Colombia | 568 children, 5–12 years | Pyrosequencing | Blood | LINE-1 | Atomic absorption technique/Venous blood | serum zinc level | No zinc showed no effect on LINE-1 methylation in total, but the LINE-1 methylation level of girls was lower compared to boys | DNA methylation was not related to erythrocyte folate, serum zinc, plasma vitamin B12 or ferritin. |
| Rodenkirchen, (2020) [14] | Germany | Healthy adults | Methylation-specific qPCR | Blood PBMC | IFN-γ and IRF-4. | Used zinc deficient, zinc adequate and zinc excessive/In-vitro | Zinc supplementation, zinc deficiency | Neither zinc-deficient nor zinc-supplemented PBMC showed a methylation pattern of the IFN-γ promoter region differing from the control | Significant increase in the cytokine’s mRNA and a reduction of IFN-γ protein level compared with zinc-supplemented cells. |
| Farahzadi, (2017) [15] | Iran | Six normal women, 45–58 years old) | Methylation-specific qPCR | Mesenchymal stem cells from adipose tissue | Human telomerase reverse transcriptase (hTERT) | Zinc deficient, zinc adequate/In-vitro | Higher and lower levels of ZnSO4 | Among the 45 sites of CpG sites, 5 sites were changed to methylated, 9 sites were changed to unmethylated and 7 unmethylated sites and 10 methylated sites remained unchanged. | Increased telomere length, the hTERT gene expression, and the telomerase activity |
| Tian, (2013) [23] | USA | Female CD1 mice | Immuno-fluorescence | Oocytes | Global DNA | Fed zinc deficient and zinc control diet/in vivo | Zinc deficiency | Decrease in global DNA methylation in zinc deficient oocytes | Increase Lap, Line-1, Sineb1 and Sineb2 transcription and decrease of Gdf9, Zp3 and Figla transcription, a significant reduction for the mature eggs to reach divided two cells |
| Finke, (2020) [24] | Germany | 18, Male C57BL/6J mice | High Performance Liquid Chromatography-Tandem Mass Spectrometry | Jejunum, liver, cortex, and kidney | Global DNA | Fed zinc deficient and zinc control diet/in vivo | Zinc deficiency | No effect on the global DNA methylation and the hydroxymethylation | Splenomegaly and genomic instability in the liver of mice |
| Davison, (2010) [25] | UK | Pregnant mice and their pups | Luminometric methylation assay (LUMA) assay using a pyrosequencer | Pups liver | Global DNA | Zn-restricted, Zn-adequate or Zn-supplemented/in-vivo | Zinc restriction, zinc supplementation | Significantly higher methylation in zinc deficient and zinc supplementation | Significant increase of DNMT1 and DNMT3a expression in higher zinc |
| Jiang, (2020) [16] | China | 32 pregnant rats | Quantitative real-time PCR. Methylation-specific PCR |
Hippocampus of offspring | BDNF promoter | Fed zinc deficient and zinc control diet/in vivo | Zinc deficiency and zinc supplementation | Reduction of BDNF methylation after zinc supplementation to offspring from zinc-deficient mother | Supplementation of zinc at age 21 to 60, improved BDNF expression but the MECP2 and GADD45b expression were still significantly lower |
| Kurita, (2012) [17] | Japan | Pregnant mice | Bisulfite genomic sequencing | Livers (approx. 0.1 g) and blood (approx. 0.2 g) specimens | Metallothionein 2 (MT) promoter | Fed zinc deficient and zinc control diet/in vivo | A significant increase in DNA methylation at the -820 CpG site, | Zn deficiency in utero induces fetal epigenetic alterations and these changes are stored as an epigenetic memory until adulthood | |
| Khadivi, (2020) [26] | Iran | 40 male rats | Immunofluorescence staining | Rats’ sperm | Global DNA | Fed zinc deficient/in vivo | Zinc supplementation against hypomethylation effect of chemotherapeutic agents. | Global DNA methylation increased compared to (bleomycin, etoposide, and cisplatin) group, yet no significant difference compared to the control group. | Improved protamination but lower than the control group. Zinc reduced DNA fragmentation compared to chemotherapeutic agents treated and exhibited recovery of body and testis weight with an increase in spermatogonia and Leydig cells |
| Hu, (2016) [18] | China | Rats and 0∼2 months offspring | Methylation-specific quantitative real-time PCR | Rats’ hippocampus | BDNF | Fed zinc deficient and zinc control diet/in vivo | zinc deficiency | DNA methylation of the BDNF exon IX was significantly increased in the zinc-deficient pups | Reduction of BDNF protein level, BDNF mRNA and DNMT3A mRNAs expression, but increase in the DNMT1 mRNA |
| Wong, (2015) [19] | USA | 10 old (92–101) and 10 young (20–28) years human, and mice | Pyrosequencing | Human lymphoblastoid cell line THP-1 cells and female C57Bl/6 mouse spleens | Human IL-6 promoter Mouse IL-6 | Zinc deficient, zinc adequate/In-vitro | Zinc deficiency | Reduced IL-6 promoter methylation in zinc deficient THP1 cells, in aged mice and in human lymphoblastoid cell lines derived from aged individuals. No significant differences in total DNA methylation levels between zinc deficiency and control groups |
Increased IL-6 protein production |