Hypomethylation enhances Ia antigen expression by the FRTL5 rat thyroid cell line.
The effect of DNA methylation on Ia antigen expression by FRTL5 rat thyroid cells was assessed using 5-azacytidine. Hypomethylation with this agent did not alone induce Ia antigen expression but did increase the expression of Ia antigen induced by suboptimal concentrations of rat gamma-interferon, present in a T cell conditioned medium or in recombinant form. These results suggest that DNA methylation does not account for the constitutive lack of Ia expression by thyroid cells, but methylation of gamma-interferon response regions may confer partial resistance to the Ia-inducing effect of this lymphokine.
Weetman
A P
AP
Department of Medicine, University of Cambridge Clinical School, Addenbrookes Hospital.
D000818:Animals; D001374:Azacitidine / Q000494:pharmacology; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D007371:Interferon-gamma / Q000494:pharmacology; D008745:Methylation; D051381:Rats; D011994:Recombinant Proteins; D013961:Thyroid Gland / Q000166:cytology* / Q000378:metabolism
D000949:Histocompatibility Antigens Class II; D011994:Recombinant Proteins; D007371:Interferon-gamma; D001374:Azacitidine