Alterations in the steroid hormone receptor co-chaperone FKBPL are associated with male infertility: a case-control study.
BACKGROUND
Male infertility is a common cause of reproductive failure in humans. In mice, targeted deletions of the genes coding for FKBP6 or FKBP52, members of the FK506 binding protein family, can result in male infertility. In the case of FKBP52, this reflects an important role in potentiating Androgen Receptor (AR) signalling in the prostate and accessory glands, but not the testis. In infertile men, no mutations of FKBP52 or FKBP6 have been found so far, but the gene for FKBP-like (FKBPL) maps to chromosome 6p21.3, an area linked to azoospermia in a group of Japanese patients.


METHODS
To determine whether mutations in FKBPL could contribute to the azoospermic phenotype, we examined expression in mouse and human tissues by RNA array blot, RT-PCR and immunohistochemistry and sequenced the complete gene from two azoospermic patient cohorts and matching control groups. FKBPL-AR interaction was assayed using reporter constructs in vitro.


RESULTS
FKBPL is strongly expressed in mouse testis, with expression upregulated at puberty. The protein is expressed in human testis in a pattern similar to FKBP52 and also enhanced AR transcriptional activity in reporter assays. We examined sixty patients from the Japanese patient group and found one inactivating mutation and one coding change, as well as a number of non-coding changes, all absent in fifty-six controls. A second, Irish patient cohort of thirty showed another two coding changes not present in thirty proven fertile controls.


CONCLUSIONS
Our results describe the first alterations in the gene for FKBPL in azoospermic patients and indicate a potential role in AR-mediated signalling in the testis.
Sunnotel
Olaf
O
Transcriptional Regulation and Epigenetics, School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, UK. o.sunnotel@ulster.ac.uk
Hiripi
Laszlo
L
Lagan
Kevin
K
McDaid
Jennifer R
JR
De León
Johanny M
JM
Miyagawa
Yasushi
Y
Crowe
Hannah
H
Kaluskar
Soniya
S
Ward
Michael
M
Scullion
Catherine
C
Campbell
Alan
A
Downes
C S
CS
Hirst
David
D
Barton
David
D
Mocanu
Edgar
E
Tsujimura
Akira
A
Cox
Marc B
MB
Robson
Tracy
T
Walsh
Colum P
CP
D000595:Amino Acid Sequence; D000818:Animals; D016022:Case-Control Studies; D015331:Cohort Studies; D008040:Genetic Linkage; D020022:Genetic Predisposition to Disease; D006801:Humans; D020104:Immunophilins / Q000235:genetics*; D007248:Infertility, Male / Q000235:genetics*; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D022021:Tacrolimus Binding Proteins; D046888:Tissue Array Analysis
C400101:FKBPL protein, human; D022021:Tacrolimus Binding Proteins; D020104:Immunophilins