The expression of Quox 1, a homeodomain-containing protein, in sympatheticganglion cells is regulated in vitro by growth factors

Quox 1, a quail homeobox gene, is the first vertebrate Antp-type homeobox g ene to be described that is expressed in the forebrain. We have already sho wn that the Quox 1 protein is specifically expressed in post-mitotic sensor y neurons. A subpopulation of sympathetic ganglion cells was also found to be labelled by anti-Quox 1 in vitro, but it is not clear whether this prote in is expressed in sympathetic ganglion cells in vivo and, if so, the condi tions which regulate its expression in vitro. In the present study, we used immunocytochemistry to find out whether Quox 1 expression in sympathetic g anglion cells in vitro is regulated by environmental signals. We found that several peptide growth factors can regulate Quox 1 expression in cultured sympathetic ganglion cells, and that they do so at physiological concentrat ion and in a variety of ways. Basic fibroblast growth factor (FGF-2) induce s Quox 1 protein expression, whereas insulin and human insulin-like growth factor-I (IGF-I) down-regulate Quox 1 expression.