Critical injury in humans induces a genomic storm with simultaneous changes in expression of innate and adaptive immunity genes.

The MUC18 antigen is an integral membrane glycoprotein of 113 kDa whose expression on primary human melanomas correlates with poor prognosis and the development of metastatic disease. MUC18 is expressed only sporadically in benign melanocytic nevi and thin primary melanomas that have a low probability of metastasizing. However, with increasing tumor thickness, MUC18 expression becomes more frequent and it is found on 80% of advanced primary tumors and metastases. MUC18-encoding cDNA clones were obtained by screening a human melanoma phage A expression library with monoclonal antibodies produced against the denatured antigen. The deduced sequence of 603 amino acids consists of a signal peptide, five immunoglobulin-like domains, a trans-

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UVA radiation is the major component of the UV solar spectrum that reaches the earth, and the therapeutic application of UVA radiation is increasing in medicine. Analysis of the cellular effects of UVA radiation has revealed that exposure of human cells to UVA radiation at physiological doses leads to increased gene expression and that this UVA response is primarily mediated through the generation of singlet oxygen. In this study, the mechanisms by which UVA radiation induces transcriptional activation of the human intercellular adhesion molecule 1 (ICAM-1) were examined. UVA radiation was capable of inducing activation of the human ICAM-1 promoter and increasing ICAM-1 mRNA and protein expression. These UVA radiation effects were inhibited by singlet oxygen quenchers, augmented by enhancement of singlet oxygen life-time, and mimicked in unirradiated cells by a singlet oxygen-generating system. UVA radiation as well as singlet oxygen-induced ICAM-1 promoter activation required activation of the transcription factor AP-2. Accordingly, both stimuli activated AP-2, and deletion of the putative AP-2-binding site abrogated ICAM-1 promoter activation in this system. This study identified the AP-2 site as the UVA radiation-and singlet oxygen-responsive element of the human ICAM-1 gene. The capacity of UVA radiation and͞or singlet oxygen to induce human gene expression through activation of AP-2 indicates a previously unrecognized role of this transcription factor in the mammalian stress response.

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