Possible involvement of GTP-Binding proteins in 1α,25-Dihydroxyvitamin D₃ induction of tissue transglutaminase in mouse peritoneal macrophages

Induction of transglutaminase was analyzed based on increases in the maximal enzymic activity and in the Northern blots of mRNA during culture of mouse resident peritoneal macrophages with active forms of hydrophobic vitamins and steroid hormones. The enzyme was induced by 1α,25-dihydroxyvitamin D₃ (1α,25-(OH)₂D₃) or retinoic acid but not by steroid hormones. The induction by 1α,25-(OH)₂D₃ was characterized by its slow onset and marked synergism with retinoic acid induction. The induction was enhanced by protein kinase activators such as cholera toxin and phorbol 12-myristate 13-acetate but largely inhibited by pertussis toxin treatment of cells. It is suggested that pertussis toxin-linked and protein kinase-related signaling would mediate the 1α,25-(OH)₂D₃-induced enzyme gene expression.