Extracellular correction of the androgen-receptor transformation defect in two families with complete androgen resistance

Abstract

We have characterized the cellular and extracellur phenotype of the mutant androgen receptor (AR) from two families who have complete androgen resistance despite a normal androgen-binding capacity ( B m ) in their genital skin fibroblasts (GSF). The cellular receptors fail to up-regulate their basal AR activity in response to prolonged incubation with 5α-dihydrotestosterone (DHT), or with two synthetic androgens, methyltrienolone (MT) and mibolerone (MB), and form A-R complexes with increased equilibrium ( K d ) and non-equilibrium (k) dissociation constants. In addition, they are thermolabile when recently dissociated, but not in their native state. A-R complexes made in normal or mutant cytosol at 4°C elute from DEAE-Sephacel at ~0.25 M KCl (untransformed), with or without prior passage through Sephadex G-25; when made in cells at 37°C, extracted with 0.4 M KCl in a buffer containing 10 mM Na 2MoO 4, and desalted by G-25, they elute at ⩽0.1 M KCl. Normal KCl-extracted DHT- and MB-R complexes dissociate (37°C) at the same slow, linear rate as their in-cell counterparts (transformed); the mutant ones dissociate more slowly than their rapidly-dissociating in-cell counterparts and, to a variable extent, nonlinearly—an early faster phase, a later slower (transformed). Thus, as judged by two conventional criteria of steroid-R complex transformation, the mutant A-R complexes can transform, possibly in two steps, under certain cell-free conditions. This behavior differentiates a class of structural AR mutations whose molecular definition awaits application of recombinant DNA techniques to the X-linked AR locus.