Characterization of alternative amino acid substitutions at arginine 830 of the androgen receptor that cause complete androgen insensitivity in three families.
We have studied two different missense mutations at arginine-830 in exon 7 of the human androgen receptor (hAR) gene that cause complete androgen insensitivity (CAIS) in three families. These substitutions result from point mutations at nucleotide 2489: a G-->T transversion causes Arg830Leu and a G-->A transition causes Arg830Gln. Genital skin fibroblasts of the patients have negligible androgen-binding capacity. The mutations were recreated in an hAR cDNA expression vector that was transiently transfected into COS-1 cells. Both mutant androgen receptors have increased dissociation rate constants and apparent equilibrium rate constants when measured with 5 alpha-dihydrotestosterone or the synthetic, nonmetabolizable androgens, mibolerone or methyltrienolone. The mutant androgen-binding activities share a distinctive thermal misbehavior. At 37 degrees C R830Q and R830L are about 40% and 10% of normal, respectively. At 22 degrees C both mutants gain androgen binding while the normal decreases by 20%; for R830Q the augmented value approaches 60% of the normal. During prolonged 18 h incubation at 37 degrees C, androgen binding of the normal AR is stable while that of both mutants decreases by at least 85%. Both mutants have a very reduced ability to transactivate a cotransfected androgen-responsive reporter gene, but R830Q is better than R830L. We conclude that arginine-830 is important for A-R complex stability, and that its replacement by glutamine or leucine yields distinctive functional aberrations.(ABSTRACT TRUNCATED AT 250 WORDS)
Shkolny
D L
DL
Lady Davis Institute for Medical Research, Montreal, Quebec, Canada.
Brown
T R
TR
Punnett
H H
HH
Kaufman
M
M
Trifiro
M A
MA
Pinsky
L
L
D000595:Amino Acid Sequence; D000728:Androgens / Q000502:physiology*; D001120:Arginine / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D012734:Disorders of Sex Development / Q000235:genetics*; D006801:Humans; D007930:Leucine / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D011485:Protein Binding; D011944:Receptors, Androgen / Q000235:genetics*; D013577:Syndrome; D014162:Transfection
D000728:Androgens; D017931:DNA Primers; D011944:Receptors, Androgen; D001120:Arginine; D007930:Leucine