title: ICAM-1 mRNA levels and relative transcription rates are decreased by UV irradiation of monocytes.
abstract: We have previously demonstrated that in vitro exposure of antigen-presenting cells to UVB radiation inhibits their ability to activate T cells through selective effects on the expression of the adhesion molecule ICAM-1 (intercellular adhesion molecule-1). Intercellular adhesion molecule-1 is an important costimulatory molecule provided by antigen-presenting cells for T-cell activation. Using human peripheral blood monocytes and the U937 human monocytoid cell line as model antigen-presenting cells, we investigated the effect of UV radiation on the mRNA steady-state levels for human ICAM-1 by northern blot analysis and relative transcription rates of ICAM-1-specific mRNA by nuclear run-on assay (NRO). Northern blot analysis demonstrated a decreased level of ICAM-1 mRNA at 4 h postradiation relative to glyceraldehyde-3-dehydrogenase mRNA. The NRO analysis demonstrated a greater than 35% decrease of newly synthesized specific mRNA at 4 h postirradiation. The results demonstrate a transcriptionally based mechanism for the diminution of both mRNA and translatable mRNA specific for ICAM-1 regulation in UV-treated antigen-presenting cells.
authors.affiliation: Department of Dermatology, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: De Luca
authors.forename: U
authors.initials: U
authors.lastname: Trefzer
authors.forename: K A
authors.initials: KA
authors.lastname: Tubesing
authors.forename: C A
authors.initials: CA
authors.lastname: Elmets
mesh_terms: D002460:Cell Line; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics*; D009000:Monocytes / Q000378:metabolism / Q000528:radiation effects*; D012333:RNA, Messenger / Q000235:genetics*; D014158:Transcription, Genetic / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D012333:RNA, Messenger; D018799:Intercellular Adhesion Molecule-1