title: Interferon effect on ribosomal ribonucleic acid related to chromosome 21 ploidy.
abstract: Antiviral and cell-growth-inhibitory activities of human interferon were shown to be related to the activity of a gene or genes present on chromosome 21. The 18s rRNA is vital to cell growth; it is capable of a viral-mRNA-recognition function and it is coded for by genes a portion of which are present on chromosome-21. A previously reported ability of human interferon to affect rRNA metabolism is characterized by a decrease in the sucrose-gradient-peak ratio of radiolabelled 28S to 18S rRNA in extracts from the cytoplasm of interferon-treated human fibroblasts. In the present report, interferon dose-response curves are presented demonstrating a direct relationship between a decrease in this ratio and interferon concentrations in the media. By using this virus-independent cytoplasmic rRNA assay, eight human fibroblast lines, differing in chromosome 21 ploidy, were tested for sensitivity to human interferon. Two monosomy-21, two euploid-21 and four trisomy-21 cell lines were tested. The monosomy-21 cell populations were significantly less sensitive to interferon than the other six cell types tested. Of the cell lines tested, the most sensitive, by a wide margin, was a trisomy-21 line. Trisomy-21 cell monolayer sensitivity, however, varied widely within the range from normal to supersensitive. These observations suggest that interferon's ability to affect rRNA metabolism is related to the activity of a gene or genes present on chromosome 21.
mesh_terms: D002460:Cell Line; D002904:Chromosomes, Human, 21-22 and Y; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000378:metabolism; D005796:Genes; D006801:Humans; D066298:In Vitro Techniques; D007372:Interferons / Q000494:pharmacology*; D009522:Newcastle disease virus; D011003:Ploidies; D012313:RNA / Q000096:biosynthesis; D012335:RNA, Ribosomal / Q000378:metabolism*
chemical_list: D012335:RNA, Ribosomal; D012313:RNA; D007372:Interferons