B-cell-specific and interferon-gamma-inducible regulation of the HLA-DR alpha gene.

Abstract

We investigated the cis-acting sequences that function in the B-cell-specific and interferon-y-inducible expression of the HLA-DRa gene, a human class II major histocompatibility complex gene. The effects of 5' deletions on the activity of the DRa promoter and the influence of upstream DRa promoter elements on the activity of the herpes simplex virus thymidine kinase promoter were examined by a transient transfection assay in human B-, T-, and fibroblast cell lines. We show that the DRa gene is regulated by positive and negative cis-acting sequences between positions -1300 and +31 from the site of initiation of transcription. We also demonstrate that the DRa promoter sequences from positions -116 to -92 and from -136 to -80 are the minimal sequences required for conferring B-cell specificity and interferon-y inducibility upon the Herpes simplex virus thymidine kinase promoter, respectively. (9). These studies strongly suggest that the cis-acting elements involved in the response to IFN-y lie in the upstream promoter region of the class II genes. Sequences from positions -109 to +31 in the DRa were reported to be sufficient for B-cell-specific expression (10). However, DNase I hypersensitivity studies in B cells revealed two additional DNase I hypersensitive sites (9). They were mapped into the first intron of the DRa gene where a lymphoid cell-specific transcriptional enhancer is located. Therefore, B-cell-specific expression of the DRa gene is likely to result from cooperative interactions between the promoter and the intronic transcriptional enhancer.Three conserved upstream sequences (CUS), which are observed in all class II genes and may play an essential role in the transcriptional regulation of these genes, have been described (11,12). In the DQ83 promoter, they are called the W-, X-, and Y-boxes and are located between positions -142 to -127, -113 to -100, and -80 to -67, respectively (13). In the DRa promoter, they are located from positions -135 to -61. We call them the Z-, X-, and Y-boxes. In this study, the function of the CUS in the B-cell-specific and IFN-yinducible expression of the DRa promoter was analyzed. We show here that sequences from positions -136 to +31 are sufficient for the appropriate expression ofthe DRa promoter in human B, T, and IFN-'y-inducible cells. Furthermore, sequences from positions -116 to -92 and from -136 to -80 confer B-cell specificity and IFN-y inducibility upon the Herpes simplex virus thymidine kinase (TK) promoter (14), respectively.

Methylation of Class IItrans-Activator Promoter IV: A Novel Mechanism of MHC Class II Gene Control

“…2 and 6). The X1 and X2 boxes are both necessary and sufficient to direct class II expression in B cells (7,8). They are bound by the regulatory factor X (RFX) 3 and cAMP response element binding protein (CREB), respectively (9 -11).…”

YB-1 DNA-binding protein represses interferon gamma activation of class II major histocompatibility complex genes.

“…Despite the similarities discussed above, the regulation of class II MHC by IFN-'y is distinct from either IFN-cff/~ regulated gene expression or IFN-'y regulated class I MHC gene expression. For example, IFN-3,-regulated class II MHC gene expression requires three separate elements (S, X, and Y) (12)(13)(14)(15)(16)(17)(18)(19) with stereospecific and distance constraints (44), whereas IFN-od/~-regulated gene expression as well as IFNy-regulated class I MHC gene expression are primarily mediated by a singular IRS. In addition, proteins that interact with the S, X, and Y elements do not cross-react with proteins that bind to the IRS.…”

“…The Y element contains an inverted CCAAT element, and the X element has been functionally divided into two subregions, X1 and X2, based on the separate interactions of these subregions with the RF-X and hXBP-1 recombinant DNA-binding proteins, respectively (10,11). The S sequence (also known as H, or W/Z which is a larger DNA sequence) is a heptamer sequence located upstream of the class II box (12)(13)(14)(15)(16)(17). These three elements are important for basal gene transcription, and thus far, they are inseparable from elements required for the IFN-T induction of class II MHC genes (12)(13)(14)(15)(16)(17)(18)(19).…”

Activated Transcription of the Human Neuropeptide Y Gene in Differentiating SH‐SY5Y Neuroblastoma Cells Is Dependent on Transcription Factors AP‐1, AP‐2α, and NGFI

“…Results were standardized, where values for uninduced resting cells were set to 1. In parallel transfection assays, pRSVCATwas used as the positive (Gorman et al, 1982) and pTKCAT (Tsang et a!., 1988;Minth-Worby, 1994) served as the negative control plasmids.…”