Resistance to several steroids in two sisters

Genome-wide Regulatory Roles of the C2H2-type Zinc Finger Protein ZNF764 on the Glucocorticoid Receptor

The C2H2-type zinc finger protein ZNF764 acts as an enhancer for several steroid hormone receptors, and haploinsufficiency of this gene may be responsible for tissue resistance to multiple steroid hormones including glucocorticoids observed in a patient with 16p11.2 microdeletion. We examined genome-wide regulatory actions of ZNF764 on the glucocorticoid receptor (GR) in HeLa cells as a model system. ZNF764- and GR-binding sites demonstrated similar distribution in various genomic features. They positioned predominantly around 50-500 kbs from the transcription start sites of their nearby genes, and were closely localized with each other, overlapping in ~37% of them. ZNF764 demonstrated differential on/off effects on GR-binding and subsequent mRNA expression: some genes were highly dependent on the presence/absence of ZNF764, but others were not. Pathway analysis revealed that these 3 gene groups were involved in distinct cellular activities. ZNF764 physically interacted with GR at ligand-binding domain through its KRAB domain, and both its physical interaction to GR and zinc finger domain appear to be required for ZNF764 to regulate GR transcriptional activity. Thus, ZNF764 is a cofactor directing GR transcriptional activity toward specific biologic pathways by changing GR binding and transcriptional activity on the glucocorticoid-responsive genes.

ZNF764 haploinsufficiency may explain partial glucocorticoid, androgen, and thyroid hormone resistance associated with 16p11.2 microdeletion

CONTEXT

Nuclear hormone receptors exert their transcriptional effects through shared cofactor molecules; thus, defects in such intermediate proteins may be associated with multiple hormone resistance. Microdeletion of small chromosomal segments results in hereditary or sporadic diseases by affecting expression of residing genes.

OBJECTIVES

We describe a 7-yr-old boy with partial resistance to glucocorticoids, thyroid hormones, and possibly androgens. He was diagnosed as being in the autism spectrum disorder and had developmental delay and several facial morphological manifestations. We explored genes responsible for multiple hormone resistance of this case.

RESULTS

We found in this patient an approximately 1.1-Mb heterozygous 16p11.2 microdeletion, which included an approximately 500-kb unique deletion along with the common, previously reported approximately 600-kb 16p11.2 microdeletion. The small interfering RNA-based screening revealed that knockdown of ZNF764, which is located in the deleted segment unique to our case, significantly reduced glucocorticoid-, androgen-, and thyroid hormone-induced transcriptional activity of their responsive genes in HeLa cells, whereas its overexpression enhanced their transcriptional activity. The activities of the estrogen and progesterone receptors, cAMP response element-binding protein, and p53 were not affected in these cells. ZNF764 (zinc finger protein 764) expression was reduced in the patient's peripheral blood mononuclear cells, whereas exogenously supplemented ZNF764 recovered responsiveness to glucocorticoids in the patient's Epstein-Barr virus-transformed lymphocytes. The effect of ZNF764 on the glucocorticoid receptor transcriptional activity was mediated through cooperation with a general nuclear hormone receptor coactivator, transcriptional intermediary factor 1.

CONCLUSIONS

ZNF764 haploinsufficiency caused by microdeletion may be responsible for the partial multiple hormone resistance observed in our patient. ZNF764 appears to be involved in glucocorticoid, androgen, and thyroid hormone action.

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.

Studies of a co-chaperone of the androgen receptor, FKBP52, as candidate for hypospadias

BACKGROUND

Hypospadias is a common inborn error of the male urethral development, for which the aetiology is still elusive. Polymorphic variants in genes involved in the masculinisation of male genitalia, such as the androgen receptor, have been associated with some cases of hypospadias. Co-regulators of the androgen receptor start being acknowledged as possible candidates for hormone-resistance instances, which could account for hypospadias. One such molecule, the protein FKBP52, coded by the FKBP4 gene, has an important physiological role in up-regulating androgen receptor activity, an essential step in the development of the male external genitalia. The presence of hypospadias in mice lacking fkbp52 encouraged us to study the sequence and the expression of FKBP4 in boys with isolated hypospadias.

PATIENTS AND METHODS

The expression of FKBP52 in the genital skin of boys with hypospadias and in healthy controls was tested by immunohistochemistry. Mutation screening in the FKBF4 gene was performed in ninety-one boys with non syndromic hypospadias. Additionally, two polymorphisms were typed in a larger cohort.

RESULTS

Immunohistochemistry shows epithelial expression of FKBP52 in the epidermis of the penile skin. No apparent difference in the FKBP52 expression was detected in healthy controls, mild or severe hypospadias patients. No sequence variants in the FKBP4 gene have implicated in hypospadias in our study.

CONCLUSION

FKBP52 is likely to play a role in growth and development of the male genitalia, since it is expressed in the genital skin of prepubertal boys; however alterations in the sequence and in the expression of the FKBP4 gene are not a common cause of non-syndromic hypospadias.

Heterogeneous nuclear ribonucleoprotein (hnRNP) binding to hormone response elements: a cause of vitamin D resistance

In previous studies, we have shown that steroid hormone resistance in New World primates occurs in the absence of abnormal expression of cognate nuclear receptors. Rather, these animals have elevated levels of heterogeneous nuclear ribonucleoproteins (hnRNPs) that act as hormone response element-binding proteins and attenuate target gene transactivation. Here we present evidence for a similar mechanism in humans via a patient with resistance to the active form of vitamin D [1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3))] who presented with normal vitamin D receptor (VDR) expression. Initial cotransfection studies showed that the cells of the patient suppressed basal and hormone-induced transactivation by wild-type VDR. Electrophoretic mobility-shift assays and Western/Southwestern blot analyses indicated that this suppressive effect was due to overexpression of a nuclear protein that specifically interacts with a DNA response element known to bind retinoid X receptor-VDR heterodimers. Ab blocking in electrophoretic mobility-shift assays indicated that this dominant-negative acting protein was in the hnRNPA family of nucleic acid-binding proteins. Further studies have shown that several members of this family, most notably hnRNPA1, were able to suppress basal and 1,25(OH)(2)D(3)-induced luciferase activity. We therefore propose that this case of vitamin D resistance in a human subject is similar to that previously described for New World primates in which abnormal expression of a hormone response element-binding protein can cause target cell resistance to 1,25(OH)(2)D(3). That this protein is a member of the hnRNP family capable of interacting with double-stranded DNA highlights a potentially important new component of the complex machinery required for steroid hormone signal transduction.