Androgen-regulated gene expression.

While a great deal of knowledge on the mechanisms of steroid hormone regulated gene expression now exists, specific information relating to androgens is lacking. A number of experimental systems have been developed and show promise as models for molecular studies of androgen regulation. Further development of these models must address the issue of whether or not the androgen receptor behaves similarly to other steroid receptors. This will require progress in the purification of the receptor itself or the cloning of its gene. Several features of androgen-regulated gene expression in the mouse kidney are applicable to a number of important biological problems. First, the presence of a variety of inducible mRNAs, whose responses to androgen are controlled at several genetic and molecular levels, should be valuable in obtaining basic information on mechanisms of gene regulation by hormones. Second, a genetic approach, for which the mouse is a convenient organism, will enable identification of novel regulatory elements that are responsible for variations in the hormonal activation of genes and that drive the evolution of species-specific gene expression phenotypes. Finally, the trophic effects of androgens in the mouse kidney afford opportunities to study a gene expression phenotype that is involved in cell growth; it will be of interest to determine how androgen induction of gene expression in kidney proximal tubule cells relates to the hormone-mediated growth of these cells.