Table 1.
Effects of short-term (6 h) FeS incubation on Pol II, H2A.Z, and H3K4m3 at four test genes and on their cognate mRNA levels
| Pol II | H2A.Z | H3K4m3 | mRNA | |
|---|---|---|---|---|
| TNF-α | ||||
| Controls | 1.0 ± 0.2 | 2.3 ± 0.2 | 32 ± 1 | 1.0 ± 0.03 |
| FeS | 1.8 ± 0.2 | 3.5 ± 0.3 | 42 ± 3 | 0.5 ± 0.1 |
| P | <0.03 | <0.01 | <0.01 | <0.001 |
| MCP-1 | ||||
| Controls | 1.2 ± 0.1 | 7.3 ± 0.3 | 46 ± 2 | 1.3 ± 0.1 |
| FeS | 2.1 ± 0.2 | 9.6 ± 0.7 | 59 ± 4 | 1.2 ± 0.01 |
| P | <0.05 | <0.02 | <0.015 | NS |
| TGF-β1 | ||||
| Controls | 2.3 ± 0.4 | 6.2 ± 0.6 | 43 ± 2 | 3.3 ± 0.5 |
| FeS | 3.4 ± 0.4 | 9.1 ± 0.8 | 60 ± 4 | 3.2 ± 0.1 |
| P | 0.06 | <0.01 | <0.001 | NS |
| HO-1 | ||||
| Controls | 1.0 ± 0.1 | 1.5 ± 0.1 | 26 ± 1 | 0.9 ± 0.05 |
| FeS | 2.2 ± 0.2 | 2.3 ± 0.2 | 38 ± 2 | 13.3 ± 0.8 |
| P | <0.001 | <0.01 | <0.001 | <0.001 |
Values are means ± SE. HK-2 cells were maintained under control conditions or challenged for 6 h with Fe sucrose (FeS), and RNA polymerase II (Pol II) binding and histone 3 lysine 4 trimethylation (H3K4m3) and histone 2 variant H2A.Z levels were analyzed by chromatin immunoprecipitation and expressed as percentage of DNA input (26). mRNA-to-GAPDH ratios were also determined. FeS induced significant increases in Pol II recruitment and modified histone enrichment at each of the 4 target genes. In the case of TNF-α, monocyte chemoattractant protein-1 (MCP-1), and transforming growth factor-β1 (TGF-β1) genes, increases in Pol II binding and H3K4m3 preceded detectable increases in their cognate mRNAs. Conversely, FeS induced an early increase in heme oxygenase-1 (HO-1) mRNA, which corresponded to increased Pol II/histone changes. NS, not significant.