Impaired nuclear translocation, nuclear matrix targeting, and intranuclear mobility of mutant androgen receptors carrying amino acid substitutions in the deoxyribonucleic acid-binding domain derived from androgen insensitivity syndrome patients.
BACKGROUND
Recent imaging studies revealed that androgen receptor (AR) is ligand-dependently translocated from the cytoplasm into the nucleus and forms intranuclear fine foci. In this study, we examined whether intracellular dynamics of mutant ARs detected in two androgen insensitivity syndrome (AIS) patients was impaired.


OBJECTIVE
ARs with mutations in the DNA-binding domain were functionally characterized and compared with the wild-type AR.


METHODS
In a complete AIS patient (subject 1), cysteine residue 579 in the first zinc finger motif of AR was substituted for phenylalanine (AR-C579F). Another mutation (AR-F582Y) was found in a partial AIS patient (subject 2).


RESULTS
AR-F582Y retained less than 10% of the transactivation activity of the wild-type AR, whereas no ligand-dependent transactivation was detected for AR-C579F. Image analyses of the receptors fused to green fluorescent protein showed that the wild-type AR was ligand-dependently translocated into the nucleus in which it formed fine subnuclear foci. Surprisingly, after the addition of dihydrotestosterone, the two mutant ARs initially formed large cytoplasmic dots, many of which were found to be close to mitochondria by electron microscopy. Subsequently, a part of the ligand-bound mutant ARs gradually entered the nucleus to form a smaller number of larger dots, compared with the wild-type AR. Fluorescence recovery after photobleaching analysis revealed that the intranuclear mobility of the mutant ARs decreased, compared with that of the wild-type AR.


CONCLUSIONS
These results suggest that the abnormal translocation, localization, and mobility of the mutant ARs may be the cause of AIS in these subjects.
Kawate
Hisaya
H
Department of Geriatric Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Wu
Yin
Y
Ohnaka
Keizo
K
Tao
Rong-Hua
RH
Nakamura
Kei-Ichiro
K
Okabe
Taijiro
T
Yanase
Toshihiko
T
Nawata
Hajime
H
Takayanagi
Ryoichi
R
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D013734:Androgen-Insensitivity Syndrome / Q000235:genetics*; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002522:Chlorocebus aethiops; D004247:DNA / Q000378:metabolism*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D015530:Nuclear Matrix / Q000378:metabolism*; D011944:Receptors, Androgen / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D011944:Receptors, Androgen; D004247:DNA