Uudermethylation of interferon-γ gene in human T cell lines and normal T lymphocytes

Abstract

The relative levels of DNA methylation at CCGG sequences within and around the interferon-gamma (IFN-gamma) gene in normal human tissues and cell lines were examined by Southern blot analysis using isoschizomeric restriction enzymes, HpaII and MspI. On the test of normal tissues, the IFN-gamma gene was undermethylated only in a small population of T lymphocyte, whereas the gene was fully methylated in T cell-depleted lymphocytes and uterus cells. In TCL-Fuj cell line which is a T cell line producing a high level of IFN-gamma spontaneously, the IFN-gamma gene was undermethylated. Moreover, the extent of DNA methylation was inversely correlated to the level of expression of the IFN-gamma gene in several T cell lines including sublines derived from TCL-Fuj cells. However, partial or complete unmethylation at the CCGG sites of IFN-gamma gene was observed in a promyelocytic leukemia cell line and two epithelial cell lines that fail to produce IFN-gamma irrespective of induction. These results suggest that undermethylation of IFN-gamma gene is necessary but not sufficient for its efficient expression.

Hypomethylation of the interferon‐γ gene correlates with its expression by primary T‐lineage cells

“…The pattern of methylation observed for a particular T-lineage cell type was virtually identical among multiple unrelated individuals, suggesting that methylation might be functionally significant. Our results are in agreement with and extend those of Funkunaga et al [30], who found modest hypomethylation of the 5' and first intron HpaII sites of the IFN-y gene in adult peripheral blood T cells but complete methylation of both sites in non-T lineage cells.…”

Inhibition of DNA methyltransferase stimulates the expression of signal transducer and activator of transcription 1, 2, and 3 genes in colon tumor cells

“…A simple explanation for the activation of IFN-responsive genes by 5-Aza-CdR is that the drug stimulated the synthesis and release of IFNs. Consistent with this possibility is the observation that the expression of IFN-␥ can be regulated by DNA methylation (40)(41)(42). We, therefore, measured the mRNA levels for IFNs-␣, -␤, and -␥ in HT29 after treatment with 500 nM 5-Aza-CdR.…”

Three different mRNAs encoding human granulocyte colony-stimulating factor receptor.

“…A total of 3.4 x 104 clones was screened by colony hybridization with a 2.5-kb HindIII/Xba I DNA fragment of murine G-CSF receptor cDNA used as a probe. Hybridization was carried out as described (16), except that the hybridization temperature was lowered to 280C, and the filter was washed at 37TC in 150 mM NaCl/15 mM sodium citrate, pH 7.0/0.1% NaDodSO4. A human placental cDNA library prepared in Agtll (Clontech) was screened by plaque-hybridization as described above.…”

“…Total RNA was prepared from various cell lines and from fresh human full-term placenta as described (18). Northern hybridization was carried out under stringent conditions (16) with the 3-kb Xho I DNA fragment of pHQ3. For DNA sequencing analysis, the DNA fragment was subcloned in the pBluescript SK(+) vector (Stratagene), and a series of deletion plasmids was generated by using exonuclease III and mung bean nuclease (18).…”