Partial purification and characterisation of the human skin fibroblast androgen receptor: Detection of abnormal receptor complexes in cells from patients with androgen insensitivity syndromes

Abstract

After incubation of hGSF with [ 3H]α-dihydrotestosterone, 17β-hydroxy-7α,17α-dimethyl-4-estrene-3-one, or 17β-hydroxy-17α-methyl-4,9,11-estrien-3-one, androgen-receptor complexes were extracted with 0.5 M KCl and precipitated by 35% ammonium sulphate. Receptor complexes from control hGSF sedimented at approximately 4S on linear 5–20% sucrose gradients. The 4S peak was diminished or absent in cells from androgen insensitive patients exhibiting absent, deficient or unstable binding of androgens in intact hGSF. This procedure may be a useful means of distinguishing quantitative and qualitative defects in androgen binding to receptor, since one cell line found to have normal levels of androgen receptor complexes in whole cell assays had a profile resembling that of receptor negative cells on sucrose gradients. The complexes from one patient with complete androgen insensitivity having normal androgen binding in intact hGSF were indistinguishable from control complexes after sucrose gradient analysis and ADP-Sepharose chromatography. Receptor complexes were eluted from the ADP-Sepharose between 0.5–1.0 M KCl. HPLC-gel filtration of androgen receptor complexes at 22°C revealed two peaks, the larger had a M r of 60–65K, Stokes radius of 3.16 nm and a frictional ratio between 1.21 and 1.43. The second peak, M 4 of 15K, was believed to represent a fragment of the receptor containing the steroid binding domain. On gel filtration at 22°C the complexes from a patient with partial androgen insensitivity, who showed a diminished 4S receptor peak on sucrose gradients, revealed only the small “meroreceptor” fragment, suggesting that the mutation in this individual might render the androgen receptor more susceptible to proteolysis in vitro.