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

Abstract.

Quox 1, a quail homeobox gene, is the first vertebrate Antp-type homeobox gene to be described that is expressed in the forebrain. We have already shown that the Quox 1 protein is specifically expressed in postmitotic sensory 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 protein is expressed in sympathetic ganglion cells in vivo and, if so, the conditions which regulate its expression in vitro. In the present study, we used immunocytochemistry to find out whether Quox 1 expression in sympathetic ganglion 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 concentration and in a variety of ways. Basic fibroblast growth factor (FGF-2) induces Quox 1 protein expression, whereas insulin and human insulin-like growth factor-I (IGF-I) down-regulate Quox 1 expression.