The control of expression of human class II MHC genes has been studied in lymphoid and melanoma cells. Specific unmethylation of all restriction sites nearby the promoter regions has been detected in all cell lines and tissues studied, irrespective of their ability to express class II MHC products. The main functional role of DNA methylation appears, on the contrary, to be the regulation of a fraction of the nucleotide polymorphism of class II MHC genes. Constitutive expression of these genes can be modified by recombinant IFN-γ and by the demethylating agent 5-azacytidine. Both the modifiers differentially regulate the levels of class II MHC and invariant chain products. In melanoma cells IFN-γ derepresses transcription of a 1.2-Kb HLA-DRα mRNA, but does not affect the levels of a 0.8-Kb HLA-DRα specific mRNA. These molecular changes are triggered by IFN-γ through a protein-synthesis-dependent pathway.
|Number of pages||16|
|Journal||Annals of the New York Academy of Sciences|
|Publication status||Published - 1987|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)