FKBP52 in Neuronal Signaling and Neurodegenerative Diseases: A Microtubule Story.

The FK506-binding protein 52 (FKBP52) belongs to a large family of ubiquitously expressed and highly conserved proteins (FKBPs) that share an FKBP domain and possess Peptidyl-Prolyl Isomerase (PPIase) activity. PPIase activity catalyzes the isomerization of Peptidyl-Prolyl bonds and therefore influences target protein folding and function. FKBP52 is particularly abundant in the nervous system and is partially associated with the microtubule network in different cell types suggesting its implication in microtubule function. Various studies have focused on FKBP52, highlighting its importance in several neuronal microtubule-dependent signaling pathways and its possible implication in neurodegenerative diseases such as tauopathies (i.e., Alzheimer disease) and alpha-synucleinopathies (i.e., Parkinson disease). This review summarizes our current understanding of FKBP52 actions in the microtubule environment, its implication in neuronal signaling and function, its interactions with other members of the FKBPs family and its involvement in neurodegenerative disease.

Virilizing oncocytic adrenocortical carcinoma: clinical and immunohistochemical studies.

CONTEXT: Oncocytic tumors of the adrenal cortex are rare, mostly nonfunctioning and benign. SETTING: Report virilizing oncocytic adrenocortical carcinoma in a 50-year-old woman. PATIENT: She presented a recent and progressive virilization syndrome, associated with high blood pressure. Hormonal evaluation showed elevated serum testosterone and delta-4-androstenedione levels, normal urinary free cortisol level and incomplete suppression of cortisol at the 1 mg dexamethasone suppression test. CT scan of the abdomen revealed a 35 mm left adrenal mass. INTERVENTION: The patient underwent a left adrenalectomy, and the histological study showed a 3 cm oncocytic adrenocortical carcinoma with signs of malignancy. RESULTS: Immunohistochemical study revealed that tumor cells expressed the steroidogenic enzymes involved into androgen synthesis (3ßHSD and P450c17α), P450 aromatase and luteinizing hormone (LH) receptors. Post-operatively, signs of virilization improved rapidly, serum testosterone and delta-4-androstenedione levels returned to normal, as did the dexamethasone suppression test. During follow-up CT-scan and 18-FDG PET/CT showed a right ovary mass, corresponding to a follicular cyst associated with hyperthecosis. The patient is alive with no recurrence 48 months after adrenal surgery. CONCLUSION: Oncocytic adrenocortical carcinomas, although extremely rare, should be considered in women with a virilization syndrome. In this woman immunohistochimical studies revealed the presence of steroidogenic enzymes involved into androgen synthesis and aromatization, and LH receptors could be implicated in this pathology.

Paradoxical resistance to high-fat diet-induced obesity and altered macrophage polarization in mineralocorticoid receptor-overexpressing mice.

The mineralocorticoid receptor (MR) exerts proadipogenic and antithermogenic effects in vitro, yet its in vivo metabolic impact remains elusive. Wild type (WT) and transgenic (Tg) mice overexpressing human MR were subjected to standard chow (SC) or high-fat diet (HFD) for 16 wk. Tg mice had a lower body weight gain than WT animals and exhibited a relative resistance to HFD-induced obesity. This was associated with a decrease in fat mass, an increased population of smaller adipocytes, and an improved glucose tolerance compared with WT animals. Quantitative RT-PCR studies revealed decreased expression of PPARγ2, a master adipogenic gene, and of glucocorticoid receptor and 11ß-hydroxysteroid dehydrogenase type 1, consistent with an impaired local glucocorticoid signaling in adipose tissues (AT). This paradoxical resistance to HFD-induced obesity was not related to an adipogenesis defect since differentiation capacity of Tg preadipocytes isolated from stroma-vascular fractions was unaltered, suggesting that other nonadipocyte factors might compromise AT development. Although AT macrophage infiltration was not different between genotypes, Tg mice exhibited a distinct macrophage polarization, as revealed by FACS analysis and CD11c/CD206 expression studies. We further demonstrated that Tg macrophage-conditioned medium partially impaired preadipocyte differentiation. Therefore, we propose that modification of M1/M2 polarization of hMR-overexpressing macrophages could account in part for the metabolic phenotype of Tg mice. Collectively, our results provide evidence that MR exerts a pivotal immunometabolic role by controlling adipocyte differentiation processes directly but also indirectly through macrophage polarization regulation. Our findings should be taken into account for the pharmacological treatment of metabolic disorders.

Concomitant Neuronal Tau Deposition and FKBP52 Decrease Is an Early Feature of Different Human and Experimental Tauopathies.

BACKGROUND: Pathological tau proteins constitute neurofibrillary tangles that accumulate in tauopathies including Alzheimer's disease (AD), progressive supranuclear palsy (PSP), and familial frontotemporal lobar degeneration (FTLD-Tau). We previously showed that the FKBP52 immunophilin interacts functionally with tau and strongly decreases in AD brain neurons in correlation with tau deposition. We also reported that FKBP52 co-localizes with autophagy-lysosomal markers and an early pathological tau isoform in AD neurons, suggesting its involvement in autophagic tau clearance. OBJECTIVE: Our objective was to evaluate if differences in neuronal FKBP52 expression levels and subcellular localization might be detected in AD, PSP, familial FTLD-Tau, and in the hTau-P301 S mouse model compared to controls. METHODS: Cell by cell immunohistofluorescence analyses and quantification of FKBP52 were performed on postmortem brain samples of some human tauopathies and on hTau-P301 S mice spinal cords. RESULTS: We describe a similar FKBP52 decrease and its localization with early pathological tau forms in the neuronal autophagy-lysosomal pathway in various tauopathies and hTau-P301 S mice. We find that FKBP52 decreases early during the pathologic process as it occurs in rare neurons with tau deposits in the marginally affected frontal cortex region of AD Braak IV brains and in the spinal cord of symptomless 1-month-old hTau-P301 S mice. CONCLUSION: As FKBP52 plays a significant role in cellular signaling and conceivably in tau clearance, our data support the idea that the prevention of FKBP52 decrease or the restoration of its normal expression at early pathologic stages might represent a new potential therapeutic approach in tauopathies including AD, familial FTLD-Tau, and PSP.

Normal spermatogenesis in a man with mutant luteinizing hormone.

Men with mutations in LHB, the gene encoding the beta subunit of luteinizing hormone (LHB), have azoospermia with absent or few fetal Leydig cells. We report a mutation in LHB in a man and his sister. The man presented with absence of virilization, undetectable luteinizing hormone, and a low serum testosterone level. He had complete spermatogenesis with a normal sperm count. The mutant luteinizing hormone had a low level of partial activity in vitro. We concluded that the residual luteinizing hormone activity, resulting in the expression of steroidogenic enzymes in few mature Leydig cells producing small amounts of intratesticular testosterone (20.2 ng per gram), was sufficient for complete and quantitatively normal spermatogenesis.

Decrease of neuronal FKBP4/FKBP52 modulates perinuclear lysosomal positioning and MAPT/Tau behavior during MAPT/Tau-induced proteotoxic stress.

Defects of autophagy-lysosomal protein degradation are thought to contribute to the pathogenesis of several neurodegenerative diseases, and the accumulation of aggregation prone proteins such as MAPT/Tau in Alzheimer disease (AD). We previously showed the localization of the immunophilin FKBP4/FKBP52 in the lysosomal system of healthy human neurons suggesting its possible role in lysosome function. We also showed that decreased FKBP4 levels in AD brain neurons correlate with abnormal MAPT accumulation and aggregation. In this study, we demonstrate that FKBP4 decrease in a human neuronal cell line (SH-SY5Y) and in dorsal root ganglion (DRG) neurons from human MAPTP301S transgenic mice affected the function of the autophagy-lysosomal system under MAPT induced proteotoxic stress conditions. We show that acute MAPT accumulation in SH-SY5Y cells induced perinuclear clustering of lysosomes, triggered FKBP4 localization around the clusters and its colocalization with MAPT and MAP1LC3/LC3-positive autophagic vesicles; a similar FKBP4 localization was detected in some AD brain neurons. We demonstrate that FKBP4 decrease altered lysosomal clustering along with MAPT and MAP1LC3 secretion increase. Although ectopic FKBP4 expression could not induce autophagy under our experimental conditions, it prevented MAPT secretion after MAPT accumulation in SH-SY5Y cells implying a regulatory role of FKBP4 on MAPT secretion. Finally, we observe that FKBP4 deficiency decreased MAP1LC3-II expression and provoked MAPT accumulation during long-term stress in mouse DRG neurons. We hypothesize that the abnormal FKBP4 decrease observed in AD brain neurons might hinder autophagy efficiency and contribute to the progression of the tauopathy by modulating MAPT secretion and accumulation during MAPT pathogenesis.Abbreviations: AD: Alzheimer disease; AKT/protein kinase B: AKT serine/threonine kinase; ALP: Autophagy-lysosomal pathway; ATG: autophagy-related; BafA1: bafilomycin A1; CQ: chloroquine; CTSD: cathepsin D; DIV: days in vitro; DRG: dorsal root ganglion neurons; Dox: doxycycline; DNAJC5: DnaJ heat shock protein family (Hsp40) member C5; EL: empty lentiviral vectors; ENO2/NSE: enolase 2, gamma neuronal; FKBP4/FKBP52: FKBP prolyl isomerase 4; FTLD-Tau: frontotemporal lobar degeneration with Tau pathology; GFP: green fluorescent protein; LAMP1: lysosomal associated membrane protein 1; LDH: lactate dehydrogenase; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MAPT/Tau: microtubule associated protein tau; MTT: tetrazolium salt; NFTs: neurofibrillary tangles; RPE-1: retinal pigment epithelial cells; shRNA: small-hairpin ribonucleic acid; SQSTM1/p62: sequestosome 1; SD: standard deviation; SEM: standard error of the mean; SH-SY5Y: human neuroblastoma cells; Sh1 or Sh2: Lentiviral shRNA vectors inducing FKBP4 decrease; SH-52GFP: MAPT/Tau-inducible SH-SY5Y cell line constitutively expressing FKBP4-GFP; TUBB3/ßIII tubulin: tubulin beta 3 class III; UPS: ubiquitin-proteasome system.

FOXL2 mutations lead to different ovarian phenotypes in BPES patients: Case Report.

FOXL2 mutations cause the autosomal dominant Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) that may be associated with premature ovarian failure (POF). However, little is known about the molecular mechanisms of FOXL2 actions in the human ovary. We conducted an extensive clinical, hormonal and ovarian histological study in two patients carrying a FOXL2 mutation associated with the typical eyelid malformations and infertility. This observational study was conducted at referral centres for POF. Histological and immunohistological studies were conducted on ovarian biopsies from two women with POF carrying a FOXL2 mutation resulting in putative polyalanine expansions of the protein. Abnormalities similar to those observed in mice with FOXL2 gene inactivation were present in the first patient's ovary, although the ovarian histology of the second patient was apparently normal. Different ovarian phenotypes, follicular defects and distribution of FOXL2 protein were observed in two patients carrying a FOXL2 mutation.

Epithelial sodium channel is a key mediator of growth hormone-induced sodium retention in acromegaly.

Acromegalic patients present with volume expansion and arterial hypertension, but the renal sites and molecular mechanisms of direct antinatriuretic action of GH remain unclear. Here, we show that acromegalic GC rats, which are chronically exposed to very high levels of GH, exhibited a decrease of furosemide-induced natriuresis and an increase of amiloride-stimulated natriuresis compared with controls. Enhanced Na(+),K(+)-ATPase activity and altered proteolytic maturation of epithelial sodium channel (ENaC) subunits in the cortical collecting ducts (CCDs) of GC rats provided additional evidence for an increased sodium reabsorption in the late distal nephron under chronic GH excess. In vitro experiments on KC3AC1 cells, a murine CCD cell model, revealed the expression of functional GH receptors and IGF-I receptors coupled to activation of Janus kinase 2/signal transducer and activator of transcription 5, ERK, and AKT signaling pathways. That GH directly controls sodium reabsorption in CCD cells is supported by: 1) stimulation of transepithelial sodium transport inhibited by GH receptor antagonist pegvisomant; 2) induction of alpha-ENaC mRNA expression; and 3) identification of signal transducer and activator of transcription 5 binding to a response element located in the alpha-ENaC promoter, indicative of the transcriptional regulation of alpha-ENaC by GH. Our findings provide the first evidence that GH, in concert with IGF-I, stimulates ENaC-mediated sodium transport in the late distal nephron, accounting for the pathogenesis of sodium retention in acromegaly.

A common African variant of human connexin 37 is associated with Caucasian primary ovarian insufficiency and has a deleterious effect in vitro.

Folliculogenesis requires communication between granulosa cells and oocytes, mediated by connexin-based gap junctions. Connexin 37 (Cx37)-deficient female mice are infertile. The present study assessed Cx37 deficiency in patients with primary ovarian insufficiency (POI). A candidate gene study was performed in patients and controls from the National Genotyping Center (Evry, France) including 58 Caucasian patients with idiopathic isolated POI and 142 Caucasian controls. Direct genomic sequencing of the coding regions of the GJA4 gene (encoding Cx37) was performed with the aim to identify a deleterious variant associated with POI and absent in ethnically matched controls. A single Cx37 variant absent in the control population was identified, namely a c.946G>A heterozygous substitution leading to a p.Gly316Ser variant that was present in two POI patients. This variant was absent in all Caucasian controls from various databases, and has been observed exclusively in African populations. This variant was identified to have a dominant negative effect in HeLa cells in vitro to alter connexon function (by 67.2±7.17%), as determined by Gap-fluorescence recovery after photobleaching. The alteration principally resulted from a decrease of cell surface connexons due to altered trafficking (by 47.73±8.59%). In marked contrast to this observation, a p.Pro258Ser variant frequent in all ethnic populations in databases had no functional effect in vitro. In conclusion, the present study reported on a Cx37 variant in two Caucasian POI patients, which was absent in control Caucasian populations, and which had a deleterious effect in vitro. It is therefore suggested that in the genetic context of the Caucasian population, this variant may contribute to POI.

Ligand-controlled interaction of histone acetyltransferase binding to ORC-1 (HBO1) with the N-terminal transactivating domain of progesterone receptor induces steroid receptor coactivator 1-dependent coactivation of transcription.

Modulators of cofactor recruitment by nuclear receptors are expected to play an important role in the coordination of hormone-induced transactivation processes. To identify such factors interacting with the N-terminal domain (NTD) of the progesterone receptor (PR), we used this domain as bait in the yeast Sos-Ras two-hybrid system. cDNAs encoding the C-terminal MYST (MOZ-Ybf2/Sas3-Sas2-Tip60 acetyltransferases) domain of HBO1 [histone acetyltransferase binding to the origin recognition complex (ORC) 1 subunit], a member of the MYST acetylase family, were thus selected from a human testis cDNA library. In transiently transfected CV1 cells, the wild-type HBO1 [611 amino acids (aa)] enhanced transcription mediated by steroid receptors, notably PR, mineralocorticoid receptor, and glucocorticoid receptor, and strongly induced PR and estrogen receptor coactivation by steroid receptor coactivator 1a (SRC-1a). As assessed by two-hybrid and glutathione-S-transferase pull-down assays, the HBO1 MYST acetylase domain (aa 340-611) interacts mainly with the NTD, and also contacts the DNA-binding domain and the hinge domains of hormone-bound PR. The HBO1 N-terminal region (aa 1-340) associates additionally with PR ligand-binding domain (LBD). HBO1 was found also to interact through its NTD with SRC-1a in the absence of steroid receptor. The latter coassociation enhanced specifically activation function 2 activation function encompassed in the LBD. Conversely, the MYST acetylase domain specifically enhanced SRC-1 coupling with PR NTD, through a hormone-dependent mechanism. In human embryonic kidney 293 cells expressing human PRA or PRB, HBO1 raised selectively an SRC-1-dependent response of PRB but failed to regulate PRA activity. We show that HBO1 acts through modification of an LBD-controlled structure present in the N terminus of PRB leading to the modulation of SRC-1 functional coupling with activation function 3-mediated transcription. Importantly, real-time RT-PCR analysis also revealed that HBO1 enhanced SRC-1 coactivation of PR-dependent transcription of human endogenous genes such as alpha-6 integrin and 11beta-hydroxydehydrogenase 2 but not that of amphiregulin. Immunofluorescence and confocal microscopy of human embryonic kidney-PRB cells demonstrated that the hormone induces the colocalization of HBO1 with PR-SRC-1 complex into nuclear speckles characteristic of PR-mediated chromatin remodeling. Our results suggest that HBO1 might play an important physiological role in human PR signaling.

The elongation factor ELL (eleven-nineteen lysine-rich leukemia) is a selective coregulator for steroid receptor functions.

The dynamic and coordinated recruitment of coregulators by steroid receptors is critical for specific gene transcriptional activation. To identify new cofactors of the human (h) mineralocorticoid receptor (MR), its highly specific N-terminal domain was used as bait in a yeast two-hybrid approach. We isolated ELL (eleven-nineteen lysine-rich leukemia), a RNA polymerase II elongation factor which, when fused to MLL (mixed lineage leukemia) contributes to the pathogenesis of acute leukemia. Specific interaction between hMR and ELL was confirmed by glutathione-S-transferase pull-down and coimmunoprecipitation experiments. Transient transfections demonstrated that ELL increased receptor transcriptional potency and hormonal efficacy, indicating that ELL behaves as a bona fide MR coactivator. Of major interest, ELL differentially modulates steroid receptor responses, with striking opposite effects on hMR and glucocorticoid receptor-mediated transactivation, without affecting that of androgen and progesterone receptors. Furthermore, the MLL-ELL fusion protein, as well as several ELL truncated mutants and the ELL L214V mutant, lost their ability to potentiate MR transcriptional activities, suggesting that both the elongation domain and the ELL-associated factor 1 interaction domains are required for ELL to fulfill its selector activity on steroid receptors. This study is the first direct demonstration of a functional interaction between a nuclear receptor and an elongation factor. These results provide further evidence that the selectivity of the mineralo vs. glucocorticoid signaling pathways also occurs at the transcriptional complex level and may have major pathophysiological implications, most notably in leukemogenesis and corticosteroid-induced apoptosis. These findings allow us to propose the concept of "transcriptional selector" for ELL on steroid receptor transcriptional functions.

Caspase-cleaved Tau-D(421) is colocalized with the immunophilin FKBP52 in the autophagy-endolysosomal system of Alzheimer's disease neurons.

Pathologic modifications of the Tau protein leading to neurofibrillary tangle (NFT) formation are a common feature of a wide range of neurodegenerative diseases known as tauopathies, which include Alzheimer's disease (AD). We previously showed that the immunophilin FKBP52 physically and functionally interacts with Tau, and we recently reported that FKBP52 levels are abnormally low in AD patients' brains. To decipher the mechanism of FKBP52 decrease in AD brains, we performed multiple labeling immunohistofluorescence and lysosomal purification using postmortem brain samples of healthy controls (n = 8) and AD (n = 20) patients. Confocal analysis revealed that FKBP52 localizes to the endolysosomal system. We also report FKBP52 colocalization with the truncated Tau-D(421) in the autophagy-endolysosomal system in some AD neurons and that the decrease of FKBP52 correlates with NFT formation. Additional experiments of autophagy inhibition in Tau-inducible SH-SY5Y cells allowed demonstrating FKBP52 release in the extracellular milieu. Our findings point out the possibility that FKBP52 could be abnormally released from NFTs negative neurons in AD brains in correlation with the early pathologic Tau-D(421) neuronal accumulation.

Ovarian steroidogenesis and serum androgen levels in patients with premature ovarian failure.

Women with premature ovarian failure (POF) have been reported to have lower serum androgen levels compared with normal women. We reviewed the androgen profiles of 143 POF patients and found androgen levels above normal for postmenopausal women in 16% of these subjects. To determine the source of androgens in those women, we studied the available ovarian biopsy samples of 15 POF patients with increased androgen levels using immunohistochemistry, with a panel of antibodies directed against the main steroidogenic enzymes. Five of the ovarian biopsies exhibited abnormal follicles characterized by hypertrophied theca interna expressing steroidogenic enzymes involved in androgen synthesis. In five other biopsies, the steroidogenic activity was scarce and confined to a small number of ovarian stromal cells, sometimes situated in the proximity of follicular remnants. Finally, in five patients, we found no histological evidence of present or past follicular development beyond the quiescent follicular stage, and no steroidogenic cells were detected by immunohistochemistry. Our findings suggest that ovarian theca-derived cells are a source of androgens in some women with POF, whereas in others, as in most postmenopausal patients, the adrenals or the ovarian hilus cells may synthesize a significant quantity of androgens under LH stimulation.

Follicle-stimulating hormone receptors in oocytes?

The regulatory mechanisms of oocyte maturation remain poorly understood. Although gonadotropins play a major role in these processes, they have generally been considered to act on somatic supportive cells, but not directly on germ cells. We have raised high affinity monoclonal antibodies against LH and FSH receptors. When using the latter to study receptor distribution in human and pig ovaries we have observed the presence of FSH (but not LH) receptors in the oocytes. FSH receptors appeared in the oocytes of primary follicles during follicular development and persisted up to the preovulatory stage. In denuded human preovulatory oocytes, FSH receptor mRNA was detected at a concentration per cell exceeding by about 20-fold that present in granulosa cells. Saturable binding of [(125)I]FSH to the membrane of oocytes was demonstrated by autoradiography. When incubated with FSH, denuded oocytes responded by a mobilization of Ca(2+). These observations concur to demonstrate the presence of functional FSH receptors in oocytes and raise the possibility of direct control of oocyte development by FSH.

RANK (receptor activator of nuclear factor kappa B) and RANK ligand are expressed in giant cell tumors of bone.

In giant cell tumors of bone (GCTBs), the mesenchymal stromal cells are the neoplastic cells and induce recruitment and formation of osteoclasts (OCs). Studies on recently discovered members of the tumor necrosis factor receptor-ligand family have demonstrated a crucial role of RANKL (receptor activator of nuclear factor kappa B [RANK] ligand) expressed by osteoblast/stromal cells and of its receptor RANK expressed by OCs during OC differentiation and activation. OCs typically are present in large numbers in GCTBs, suggesting that these tumors may contain cells expressing factors that stimulate OC precursor recruitment and differentiation. We used immunohistochemical analysis to study RANKL and RANK expression in 5 GCTBs. Multinucleated cells and some mononuclear cells showed strong positive staining with anti-RANK antibodies; RANKL was present in a subset of mononuclear cells that did not express the hematopoietic lineage cell marker CD45, a feature that identified them as mesenchymal tumor cells. Our results suggest that RANKL expression may have a role in the pathogenesis of GCTBs and in the formation of the large OC population present in these tumors.

Hyperandrogenism in a postmenopausal woman presenting with a metastatic ileum endocrine tumor.

OBJECTIVE: To elucidate the mechanism of the hyperandrogenism found in a postmenopausal woman presenting an ileum endocrine tumor with ovarian metastases. DESIGN: Case report. SETTING: University hospital. PATIENT(S): A postmenopausal woman was referred for hirsutism. Basal plasma testosterone was high, 6.6 nM/L (normal,

Ligand-dependent stabilization of androgen receptor in a novel mouse ST38c Sertoli cell line.

Mature Sertoli cells (SC) are critical mediators of androgen regulation of spermatogenesis, via the androgen receptor (AR) signaling. Available immortalized SC lines loose AR expression or androgen responsiveness, hampering the study of endogenous AR regulation in SC. We have established and characterized a novel clonal mouse immortalized SC line, ST38c. These cells express some SC specific genes (sox9, wt1, tjp1, clu, abp, inhbb), but not fshr, yet more importantly, maintain substantial expression of endogenous AR as determined by PCR, immunocytochemistry, testosterone binding assays and Western blots. Microarrays allowed identification of some (146) but not all (rhox5, spinlw1), androgen-dependent, SC expressed target genes. Quantitative Real-Time PCR validated regulation of five up-regulated and two down-regulated genes. We show that AR undergoes androgen-dependent transcriptional activation as well as agonist-dependent posttranslational stabilization in ST38c cells. This cell line constitutes a useful experimental tool for future investigations on the molecular and cellular mechanisms of androgen receptor signaling in SC function.

Progesterone receptor isoforms PRA and PRB differentially contribute to breast cancer cell migration through interaction with focal adhesion kinase complexes.

Progesterone receptor (PR) and progestins affect mammary tumorigenesis; however, the relative contributions of PR isoforms A and B (PRA and PRB, respectively) in cancer cell migration remains elusive. By using a bi-inducible MDA-MB-231 breast cancer cell line expressing PRA and/or PRB, we analyzed the effect of conditional PR isoform expression. Surprisingly, unliganded PRB but not PRA strongly enhanced cell migration as compared with PR(-) cells. 17,21-Dimethyl-19-norpregna-4,9-dien-3,20-dione (R5020) progestin limited this effect and was counteracted by the antagonist 11ß-(4-dimethyl-amino)-phenyl-17ß-hydroxy-17-(1-propynyl)-estra-4,9-dien-3-one (RU486). Of importance, PRA coexpression potentiated PRB-mediated migration, whereas PRA alone was ineffective. PR isoforms differentially regulated expressions of major players of cell migration, such as urokinase plasminogen activator (uPA), its inhibitor plasminogen activator inhibitor type 1, uPA receptor (uPAR), and ß1-integrin, which affect focal adhesion kinase (FAK) signaling. Moreover, unliganded PRB but not PRA enhanced FAK Tyr397 phosphorylation and colocalized with activated FAK in cell protrusions. Because PRB, as well as PRA, coimmunoprecipitated with FAK, both isoforms can interact with FAK complexes, depending on their respective nucleocytoplasmic trafficking. In addition, FAK degradation was coupled to R5020-dependent turnovers of PRA and PRB. Such an effect of PRB/PRA expression on FAK signaling might thus affect adhesion/motility, underscoring the implication of PR isoforms in breast cancer invasiveness and metastatic evolution with underlying therapeutic outcomes.

The mineralocorticoid signaling pathway throughout development: expression, regulation and pathophysiological implications.

The mineralocorticoid signaling pathway has gained interest over the past few years, considering not only its implication in numerous pathologies but also its emerging role in physiological processes during kidney, brain, heart and lung development. This review aims at describing the setting and regulation of aldosterone biosynthesis and the expression of the mineralocorticoid receptor (MR), a nuclear receptor mediating aldosterone action in target tissues, during the perinatal period. Specificities concerning MR expression and regulation during the development of several major organs are highlighted. We provide evidence that MR expression is tightly controlled in a tissue-specific manner during development, which could have major pathophysiological implications in the neonatal period.