Transcriptional regulation of the MHC II gene DRA in untransformed human thyrocytes
Wu ; Z. ; - ASI Sponsor
Apr - 2000
ISSN : 14602377 ;
journal : International Immunology

Issue : 4
type: Article Journal

Abstract
MHC class II molecules are heterodimeric, polymorphic transmembrane glycoproteins physiologically expressed on cells of the immune system and pathologically expressed on the affected target cells of autoimmunity. Their function is to present processed peptides to antigen-specific CD4+ T cells. To understand the molecular mechanism of the regulation of class II genes in autoimmune target cell thyrocytes, we investigated the transcriptional regulation of DRA on untransformed, differentiated human thyroid cells following IFN-\gamma\ stimulation, which is potentially relevant to the inappropriate class II expression found in Graves disease. Data from this study show that IFN-\gamma\ enhances a promoter Y box binding protein and induces an X box binding protein in untransformed thyrocytes, but not in SV-40-transfected thyrocytes. Initial characterization of the proteins has indicated that the Y box binding protein is 132 kDa in size while the X box binding protein binds to the X2 region and is 116 kDa. The X box binding protein may correspond to poly(ADP-ribose) polymerase, a recently described component of the X2 box binding protein, X2BP. In addition, the signal transducer and activator of transcription 1\alpha\ protein (STAT1\alpha\) is also induced by IFN-\gamma\ in these cells. These results further suggest that there are differences in class II gene regulation between differentiated cells and transformed cell lines.

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