Estrogen-induced abnormally high cystic fibrosis transmembrane conductance regulator expression results in ovarian hyperstimulation syndrome

Androgen-induced upregulation of CFTR in pancreatic β-cell contributes to hyperinsulinemia in PCOS model

PURPOSE

Polycystic ovarian syndrome (PCOS) is an endocrine-metabolic condition affecting 5-10% of reproductive-aged women and characterized by hyperandrogenism, insulin resistance (IR), and hyperinsulinemia. CFTR is known to be regulated by steroid hormones, and our previous study has demonstrated an essential role of CFTR in β-cell function. This study aims to investigate the contribution of androgen and CFTR to hypersecretion of insulin in PCOS and the underlying mechanism.

METHODS

We established a rat PCOS model by subcutaneously implanting silicon tubing containing Dihydrotestosterone (DHT). Glucose tolerance test with insulin levels was performed at 9 weeks after implantation. A rat β-cell line RINm5F, a mouse β-cell line β-TC-6, and mouse islets were treated with DHT, and with or without the androgen antagonist flutamide for CFTR and insulin secretion-related functional assays or mRNA/protein expression measurement. The effect of CFTR inhibitors on DHT-promoted membrane depolarization, glucose-stimulated intracellular Ca2+ oscillation and insulin secretion were examined by membrane potential imaging, calcium imaging and ELISA, respectively.

RESULTS

The DHT-induced PCOS model showed increased body weight, impaired glucose tolerance, and higher blood glucose and insulin levels after glucose stimulation. CFTR was upregulated in islets of PCOS model and DHT-treated cells, which was reversed by flutamide. The androgen receptor (AR) could bind to the CFTR promoter region, which was enhanced by DHT. Furthermore, DHT-induced membrane depolarization, enhanced glucose-stimulated Ca2+ oscillations and insulin secretion, which could be abolished by CFTR inhibitors.

CONCLUSIONS

Excessive androgen enhances glucose-stimulating insulin secretion through upregulation of CFTR, which may contribute to hyperinsulinemia in PCOS.

Estrogenic Modulation of Ionic Channels, Pumps and Exchangers in Airway Smooth Muscle

To preserve ionic homeostasis (primarily Ca²⁺, K⁺, Na⁺, and Cl^-), in the airway smooth muscle (ASM) numerous transporters (channels, exchangers, and pumps) regulate the influx and efflux of these ions. Many of intracellular processes depend on continuous ionic permeation, including exocytosis, contraction, metabolism, transcription, fecundation, proliferation, and apoptosis. These mechanisms are precisely regulated, for instance, through hormonal activity. The lipophilic nature of steroidal hormones allows their free transit into the cell where, in most cases, they occupy their cognate receptor to generate genomic actions. In the sense, estrogens can stimulate development, proliferation, migration, and survival of target cells, including in lung physiology. Non-genomic actions on the other hand do not imply estrogen's intracellular receptor occupation, nor do they initiate transcription and are mostly immediate to the stimulus. Among estrogen's non genomic responses regulation of calcium homeostasis and contraction and relaxation processes play paramount roles in ASM. On the other hand, disruption of calcium homeostasis has been closely associated with some ASM pathological mechanism. Thus, this paper intends to summarize the effects of estrogen on ionic handling proteins in ASM. The considerable diversity, range and power of estrogens regulates ionic homeostasis through genomic and non-genomic mechanisms.

Increasing incidence rate of breast cancer in cystic fibrosis - relationship between pathogenesis, oncogenesis and prediction of the treatment effect in the context of worse clinical outcome and prognosis of cystic fibrosis due to estrogens

Cystic fibrosis (CF) is the most common genetic disease in the Caucasion population. Thanks to the CFTR modulators therapy, life expectancy will significantly improve. New therapeutic challenges can be expected, including diseases associated with ageing and higher incidence of cancer, as evidenced by recent epidemiological studies. The increasing incidence of tumors includes also breast cancer. The risk of breast cancer is higher in CF patients compared to the general population. Sex hormones, especially estrogens, also affect on the pathophysiology and immunology of the CF. Previous research, has demonstrated unequivocal survival rates for female CF patients compared to their male counterparts. Is demonstrated, that chemotherapy used for breast cancer affects the CFTR channel and CFTR modulator therapy has frequent side effects on breast tissue. In this review, we focus on the effects of female sex hormones on CF disease, pathophysiological relationships between CF and breast cancer, and the impact of antitumor treatment on both, malignant disease and CF. The potential for further investigation is also discussed.

Gain- and Loss-of-Function CFTR Alleles Are Associated with COVID-19 Clinical Outcomes

Carriers of single pathogenic variants of the CFTR (cystic fibrosis transmembrane conductance regulator) gene have a higher risk of severe COVID-19 and 14-day death. The machine learning post-Mendelian model pinpointed CFTR as a bidirectional modulator of COVID-19 outcomes. Here, we demonstrate that the rare complex allele [G576V;R668C] is associated with a milder disease via a gain-of-function mechanism. Conversely, CFTR ultra-rare alleles with reduced function are associated with disease severity either alone (dominant disorder) or with another hypomorphic allele in the second chromosome (recessive disorder) with a global residual CFTR activity between 50 to 91%. Furthermore, we characterized novel CFTR complex alleles, including [A238V;F508del], [R74W;D1270N;V201M], [I1027T;F508del], [I506V;D1168G], and simple alleles, including R347C, F1052V, Y625N, I328V, K68E, A309D, A252T, G542*, V562I, R1066H, I506V, I807M, which lead to a reduced CFTR function and thus, to more severe COVID-19. In conclusion, CFTR genetic analysis is an important tool in identifying patients at risk of severe COVID-19.

Sex disparities in cystic fibrosis: review on the effect of female sex hormones on lung pathophysiology and outcomes

Sex differences in morbidity and mortality have been reported in the cystic fibrosis (CF) population worldwide. However, it is unclear why CF women have worse clinical outcomes than men. In this review, we focus on the influence of female sex hormones on CF pulmonary outcomes and summarise data from in vitro and in vivo experiments on how oestrogen and progesterone might modify mucociliary clearance, immunity and infection in the CF airways. The potential for novel sex hormone-related therapeutic interventions is also discussed.

A disparity in survival has been noted between men and women with cystic fibrosis where female sex hormones may facilitate lung disease progression. There is strong evidence that implicates oestrogen in numerous aspects of CF airway pathophysiology.https://bit.ly/34ef4Cv

Melatonin stimulates aromatase expression and estradiol production in human granulosa-lutein cells: relevance for high serum estradiol levels in patients with ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) is one of the most life-threatening and potentially fatal complications associated with controlled ovarian hyperstimulation (COH) during in vitro fertilization (IVF) treatment. Although the pathogenesis of OHSS remains unclear, elevated serum estradiol (E2) levels before human chorionic gonadotropin (hCG) administration are associated with the risk of OHSS. The pineal hormone melatonin and its receptors are expressed in human granulosa cells and have been shown to stimulate E2 production. However, the effect of melatonin on the expression of aromatase, an enzyme responsible for a key step in the biosynthesis of E2, in human granulosa cells remains to be determined. Here, we demonstrate that melatonin upregulates aromatase expression in primary cultured human granulosa-lutein (hGL) cells through the melatonin receptor-mediated PKA-CREB pathway. Using a mouse model of OHSS, we demonstrate that administration of the melatonin receptor inhibitor luzindole inhibits the development of OHSS. In addition, the expression of ovarian aromatase and serum E2 levels are upregulated in OHSS mice compared to control mice, but this upregulation is attenuated by inhibition of the function of melatonin. Moreover, clinical results reveal that aromatase expression levels are upregulated in hGL cells from OHSS patients. Melatonin and E2 levels in the follicular fluid are significantly higher in OHSS patients than in non-OHSS patients. Furthermore, melatonin levels are positively correlated with E2 levels in follicular fluid. This study helps to elucidate the mechanisms mediating the expression of aromatase in hGL cells and provides a potential mechanism explaining the high E2 levels in patients with OHSS.

Blocking the activity of melatonin helps prevent female mice from developing swollen ovaries, a potentially life-threatening complication of assisted fertilization techniques. A research team from China’s First Affiliated Hospital of Zhengzhou University, led by Jung-Chien Cheng and Ying-Pu Sun, demonstrated that melatonin, a hormone found in the fluid that surrounds developing eggs, can induce ovarian cells to boost expression of aromatase. This enzyme is responsible for synthesizing estradiol, a hormone involved in female reproduction. Women whose ovaries became over-stimulated in response to fertility medications showed elevated levels of melatonin, aromatase and estradiol. Inhibiting the function of melatonin reduced symptoms in mouse models of ovarian hyperstimulation syndrome. The findings reveal an important role of melatonin in ovarian enlargement and point to new therapeutic strategies for women undergoing in vitro fertilization.

Successful reversal of ovarian hyperstimulation syndrome in a mouse model by rapamycin, an mTOR pathway inhibitor

Ovarian hyperstimulation syndrome (OHSS) is a potentially life-threatening, iatrogenic complication of ovarian stimulation in assisted reproduction technology. This complex syndrome is characterised by enlarged ovaries with multiple corpora luteum, elevated sex steroid hormones in serum and increased capillary permeability. Until now, the pathogenesis of OHSS remains obscure, and no absolute strategy can fully prevent OHSS without any side effect on ovulation and clinical pregnancy. Using cultured human or mouse granulosa cells, our study revealed the time-dependent activation of the mTOR signaling pathway after human chorionic gonadotropin (hCG) treatment. The involvement of the mTOR signaling pathway was also observed in the development of OHSS in a mouse model. Selectively inhibiting mTOR signals by only two injections of rapamycin (2 mg/kg body weight), before or just after hCG treatment, significantly reduced vascular leakage and the severity of OHSS symptoms. Although ovarian angiogenesis was significantly inhibited, rapamycin could not decrease the elevated levels of vascular endothelial growth factor, IL-6 and IL-11 in OHSS ovaries. Further study showed the functional roles of the mTOR signaling pathway in the hyperstimulation-induced ovarian extracellular matrix remodeling as the expression of α2M, a broad proteolytic inhibitor in both ovary and serum, was dramatically decreased after rapamycin treatment. Since a single injection of rapamycin during superovulation had no side effects on ovulation and early embryonic development, we propose rapamycin may be a good candidate to lower and prevent the risk of OHSS in the future.

Pharmacokinetics and Bioavailability of the GnRH Analogs in the Form of Solution and Zn2+-Suspension After Single Subcutaneous Injection in Female Rats

BACKGROUND AND OBJECTIVES

Although many synthetic gonadoliberin analogs have been developed, only a few of them, including buserelin, were introduced into clinical practice. Dalarelin, which differs from buserelin by just one aminoacid in the position 6 (D-Ala), is not widely used so far. Gonadotropin-releasing hormone (GnRH) analogs are used to treat many different illnesses and are available in different forms like solution for injection, nasal spray, microspheres, etc. Unfortunately, none of the above drug formulations can release the hormones for 24 h. We assumed that classical suspension could solve this problem.

METHODS

Two sets of experiments were performed. In the first one, buserelin and dalarelin were injected into mature female rats in two forms: suspension, in which the analogs are bounded by Zn²⁺ ions and solution. The pharmacokinetic parameters and bioavailability of the analogs were calculated, based on their concentration in the plasma measured by high-performance liquid chromatography method (HPLC). In the second experiment, the hormones in two different forms were injected into superovulated immature female rats and then the concentration of Luteinizing hormone (LH), Follicle-stimulating hormone (FSH) and 17β-estradiol in the serum was measured by radioimmunological method.

RESULTS

The Extent of Biological Availability (EBA), calculated on the base of AUC_0-∞, showed that in the form of solution buserelin and dalarelin display, respectively, only 13 and 8 % of biological availability of their suspension counterparts. Comparing both analogs, the EBA of dalarelin was half (53 %) that of buserelin delivered in the form of solution and 83 % when they were delivered in the form of suspension. The injection of buserelin or dalarelin, in the form of solution or suspension, into superovulated female rats increased LH, FSH and estradiol concentration in the serum. However, after injection of the analogs in the form of suspension, the high concentration of LH and FSH in the serum persisted longer.

CONCLUSION

Performed studies indicate that GnRH analogs in the form of suspension have higher bioavailability than their solution counterparts. It influences the effects of their action, especially in relation to LH and FSH.

CFTR-regulated MAPK/NF-κB signaling in pulmonary inflammation in thermal inhalation injury

The mechanism underlying pulmonary inflammation in thermal inhalation injury remains elusive. Cystic fibrosis, also hallmarked with pulmonary inflammation, is caused by mutations in CFTR, the expression of which is temperature-sensitive. We investigated whether CFTR is involved in heat-induced pulmonary inflammation. We applied heat-treatment in 16HBE14o- cells with CFTR knockdown or overexpression and heat-inhalation in rats in vivo. Heat-treatment caused significant reduction in CFTR and, reciprocally, increase in COX-2 at early stages both in vitro and in vivo. Activation of ERK/JNK, NF-κB and COX-2/PGE2 were detected in heat-treated cells, which were mimicked by knockdown, and reversed by overexpression of CFTR or VX-809, a reported CFTR mutation corrector. JNK/ERK inhibition reversed heat-/CFTR-knockdown-induced NF-κB activation, whereas NF-κB inhibitor showed no effect on JNK/ERK. IL-8 was augmented by heat-treatment or CFTR-knockdown, which was abolished by inhibition of NF-κB, JNK/ERK or COX-2. Moreover, in vitro or in vivo treatment with curcumin, a natural phenolic compound, significantly enhanced CFTR expression and reversed the heat-induced increases in COX-2/PGE2/IL-8, neutrophil infiltration and tissue damage in the airway. These results have revealed a CFTR-regulated MAPK/NF-κB pathway leading to COX-2/PGE2/IL-8 activation in thermal inhalation injury, and demonstrated therapeutic potential of curcumin for alleviating heat-induced pulmonary inflammation.

Co action of CFTR and AQP1 increases permeability of peritoneal epithelial cells on estrogen-induced ovarian hyper stimulation syndrome

Background

Ovarian hyper stimulation syndrome (OHSS) is an iatrogenic complication associated with fertility drugs. It is characterized by increased vascular permeability and substantial fluid shift with accumulation in the body cavity. The pathogenesis of OHSS remains obscure, and no definitive treatments are currently available.

Results

Using western blot and short-circuit current (Isc) techniques, we investigate the potential coactions of analysis in cystic fibrosis transmembrane conductance regulator (CFTR) and aquaporin 1 (AQP1) on the hyper permeability of body cavity peritoneal epithelial cells in the pathogenesis of OHSS. The rats develop OHSS symptoms, with the up regulation of both CFTR and AQP1 expression and enhanced CFTR channel activity in peritoneal epithelial cells, can also be mimicked by administration of estrogen, alone in ovariectomized rats. Administration of progesterone suppresses CFTR activity, OHSS symptoms as well as CFTR and AQP1 expression. Besides, AQP1 inhibitor, HgCl₂, can suppress CFTR channel activity. Therefore, antisera against CFTR or AQP1 to OHSS animals may result in alleviation of the symptom.

Conclusion

This study confirms the coactions of CFTR and AQP1 play a critical role in the development and progression of increased peritoneal epithelial permeability in severe OHSS. These findings may provide grounds for ameliorating assisted reproduction treatment strategy to reduce the risk of OHSS in in vitro fertilization (IVF).

Resveratrol rescues cAMP-dependent anionic transport in the cystic fibrosis pancreatic cell line CFPAC1

BACKGROUND AND PURPOSE

The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-dependent chloride channel in the plasma membrane of epithelia whose mutation is the cause of the genetic disease cystic fibrosis (CF). The most frequent CFTR mutation is deletion of Phe(508) and this mutant protein (delF508CFTR) does not readily translocate to the plasma membrane and is rapidly degraded within the cell. We hypothesized that treating epithelial cells with resveratrol, a natural polyphenolic, phyto-ooestrogenic compound from grapes, could modulate both the expression and localization of CFTR.

EXPERIMENTAL APPROACH

Cells endogenously expressing CFTR (MDCK1 and CAPAN1 cells) or delF508CFTR (CFPAC1 and airway epithelial cells, deriving from human bronchial biopsies) were treated with resveratrol for 2 or 18 h. The effect of this treatment on CFTR and delF508CFTR expression and localization was evaluated using RT-PCR, Western blot and immunocytochemistry. Halide efflux was measured with a fluorescent dye and with halide-sensitive electrodes. Production of interleukin-8 by these cells was assayed by ELISA.

KEY RESULTS

Resveratrol treatment increased CFTR expression or maturation in immunoblotting experiments in MDCK1 cells or in CFPAC1 cells. Indirect immunofluorescence experiments showed a shift of delF508CFTR localization towards the (peri)-membrane area in CFPAC1 cells and in human airway epithelial cells. A cAMP-dependent increase in membrane permeability to halide was detected in resveratrol-treated CFPAC1 cells, and was inhibited by a selective inhibitor of CFTR.

CONCLUSION AND IMPLICATIONS

These results show that resveratrol modulated CFTR expression and localization and could rescue cAMP-dependent chloride transport in delF508CFTR cells.

The pathophysiology of ovarian hyperstimulation syndrome: an unrecognized compartment syndrome

OBJECTIVE

To compare and contrast the pathophysiology of ovarian hyperstimualtion syndrome (OHSS) with known syndromes of increased intraabdominal pressure (IAP), and to explore the relationship of increased IAP with symptom severity in OHSS.

DESIGN

Literature review.

MAIN OUTCOME MEASURE(S)

Correlation of OHSS symptoms with IAP; effects of paracentesis on IAP in patients with OHSS.

SETTING

Academic Research Institution.

INTERVENTION(S)

None.

RESULT(S)

OHSS involves a rapid accumulation of volume (from 1.5-17 liters) in the peritoneal cavity that can lead to organ dysfunction, including respiratory impairment and oliguria. In published reports of 20 moderate-to-severe OHSS patients in whom IAP was measured, IAP was found to be elevated to a pathologic range. The increased IAP indicates that OHSS may be considered a compartment syndrome and meets criteria for abdominal compartment syndrome in advanced cases. For this reason, management of OHSS should include reduction of pressure by paracentesis to avoid morbidity and syndrome progression. In addition, measurement of IAP may help to classify the stage of OHSS.

CONCLUSION(S)

IAP was found to be elevated in the few cases of OHSS in which it was measured, substantiating the conclusion that OHSS may be considered a compartment syndrome. An understanding of the pathophysiology of increased intrabdominal pressure is useful in the management of OHSS.

Involvement of cystic fibrosis transmembrane conductance regulator (CFTR) in the pathogenesis of hydrosalpinx induced by Chlamydia trachomatis infection

BACKGROUND

Genital Chlamydia (C) trachomatis infection has been recognized as the single most common cause of pelvic inflammatory disease leading to severe tubal damage, ectopic pregnancy, infertility and hydrosalpinx. However, the mechanism underlying the formation of hydrosalpinx induced by C. trachomatis infection remains largely unknown. We performed this study to determine the involvement of cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated chloride channel that regulates epithelial electrolyte and fluid secretion, in hydrosalpinx fluid formation.

METHODS

Western blot analysis was used to determine CFTR expression in the hydrosalpinges that were seen on the ultrasound scans of infertile assisted reproduction treatment patients. Correlation with C. trachomatis infection was done by testing patients' sera for C. trachomatis immunoglobulin G antibody titer using a Capita enzyme-linked immunosorbent assay based kit. CFTR involvement was further verified in a rat C. trachomatis infection model and confirmed using CFTR mutant (CFTR(tm1Unc)) mice.

RESULTS

Here we report on the up-regulated expression of CFTR in the hydrosalpinx tissues of infertile patients with detectable serum levels of C. trachomatis antibody (immunoglobulin G). In a rat model, increased CFTR expression and fluid accumulation could be observed in the uterine horns infected with C. trachomatis elementary bodies, which was reversed by antibiotics treatment. In C. trachomatis-infected CFTR(tm1Unc) mice, however, no detectable fluid accumulation was observed.

CONCLUSION

These findings suggest the involvement of CFTR in the pathogenesis of hydrosalpinx fluid formation and may provide grounds for a better treatment strategy to improve assisted reproduction treatment outcome in infertile patients with hydrosalpinx.

Cystic fibrosis and estrogens: a perfect storm

Irreversible destruction and widening of the airways due to acquired infections or genetic mutations as well as those of unknown cause are more severe in females. Differences between male and female anatomy, behavior, and hormonal state have been proposed to explain the increased incidence and severity in females with airway disease such as cystic fibrosis (CF); however, a mechanism to explain a sex-related difference has remained elusive. In this issue of the JCI, Coakley et al. report that elevations in the major estrogen hormone in humans--17beta-estradiol--reduce Ca2+-activated Cl- secretion by airway epithelial cells in culture, thereby disrupting ion and water balance (see the related article beginning on page 4025). They measure a similar diminution of nasal epithelial Ca2+-activated Cl- secretion in women with CF during the menstrual cycle phase at which 17beta-estradiol level is at its highest. These data suggest that for about one week of a four-week menstrual cycle, women with CF will have a reduced ability to efficiently clear airway secretions, the buildup of which is a hallmark of CF. The authors suggest that these data warrant the testing of antiestrogen therapy in females with CF and propose an alternative avenue for CF therapeutic development.

The cystic fibrosis transmembrane conductance regulator in reproductive health and disease

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel regulated by cAMP-dependent phosphorylation, which is expressed in epithelial cells of a wide variety of tissues including the reproductive tracts. Mutations in the gene encoding CFTR cause cystic fibrosis, a common genetic disease in Caucasian populations with a multitude of clinical manifestations including infertility/subfertility in both sexes. However, the physiological role of CFTR in reproduction and its involvement in the pathogenesis of reproductive diseases remain largely unknown. This review discusses the role of CFTR in regulating fluid volume and bicarbonate secretion in the reproductive tracts and their importance in various reproductive events. We also discuss the contribution of CFTR dysfunction to a number of pathological conditions. The evidence presented is consistent with an important role of CFTR in reproductive health and disease, suggesting that CFTR might be a potential target for the diagnosis and treatment of reproductive diseases including infertility.

Morphologic effects of epithelial ion channels on the mouse uterus: differences between raloxifene analog (LY117018) and estradiol treatments

OBJECTIVE

Estrogen regulates the expression of epithelial Na(+) channel (ENaC) and cystic fibrosis transmembrane conductance regulator (CFTR). Our purpose was to assess the effects of raloxifene analog LY117018 on the expression of ENaC and CFTR in ovariectomized mice.

STUDY DESIGN

Three groups of 5 female ovariectomized mice were treated with 17beta-estradiol benzoate (E2), LY117018 (LY), or vehicle, respectively, for 4-12 weeks. Effects on the messenger ribonucleic acid expression levels of ENaC and CFTR channels in the uterus were studied using real-time reverse transcriptase-polymerase chain reaction.

RESULTS

E2 treatment induced CFTR expression, repressed ENaC expression and resulted in fluid accumulation in the uterus. In contrast, LY induced CFTR expression, did not repress ENaC expression, and caused no fluid accumulation.

CONCLUSION

Estradiol and LY117018 differentially regulate the expression of CFTR and ENaC in ovariectomized mouse uterus. This finding suggests that uterine fluid accumulation can be controlled mainly by targeting the ENaC.

Beta-oestradiol rescues DeltaF508CFTR functional expression in human cystic fibrosis airway CFBE41o- cells through the up-regulation of NHERF1

BACKGROUND INFORMATION

CF (cystic fibrosis) is a disease caused by mutations within the CFTR (CF transmembrane conductance regulator) gene. The most common mutation, DeltaF508 (deletion of Phe-508), results in a protein that is defective in folding and trafficking to the cell surface but is functional if properly localized in the plasma membrane. We have recently demonstrated that overexpression of the PDZ protein NHERF1 (Na(+)/H(+)-exchanger regulatory factor 1) in CF airway cells induced both a redistribution of DeltaF508CFTR from the cytoplasm to the apical membrane and the PKA (protein kinase A)-dependent activation of DeltaF508CFTR-dependent chloride secretion. In view of the potential importance of the targeted up-regulation of NHERF1 in a therapeutic context, and since it has been demonstrated that oestrogen treatment increases endogenous NHERF1 expression, we tested the hypothesis that oestrogen treatment can increase NHERF1 expression in a human bronchiolar epithelial CF cell line, CFBE41o(-), with subsequent rescue of apical DeltaF508CFTR chloride transport activity.

RESULTS

We found that CFBE41o(-) cells do express ERs (oestrogen receptors) in the nuclear fraction and that beta-oestradiol treatment was able to significantly rescue DeltaF508CFTR-dependent chloride secretion in CFBE41o(-) cell monolayers with a peak between 6 and 12 h of treatment, demonstrating that the DeltaF508CFTR translocated to the apical membrane can function as a cAMP-responsive channel, with a significant increase in chloride secretion noted at 1 nM beta-oestradiol and a maximal effect observed at 10 nM. Importantly, knock-down of NHERF1 expression by transfection with siRNA (small interfering RNA) for NHERF1 inhibited the beta-oestradiol-dependent increase in DeltaF508CFTR protein expression levels and completely prevented the beta-oestradiol-dependent rescue of DeltaF508CFTR transport activity.

CONCLUSIONS

These results demonstrate that beta-oestradiol-dependent up-regulation of NHERF1 significantly increases DeltaF508CFTR functional expression in CFBE41o(-) cells.

Infertility in females with cystic fibrosis is multifactorial: evidence from mouse models

Infertility is commonly associated with cystic fibrosis (CF). Although infertility in men with CF has been thoroughly investigated, the infertility observed in women with CF has not been well studied. To investigate female infertility associated with CF, we used two independently derived mouse models of CF. Both of these models displayed decreased fertility characterized by a reduction in litter number and litter size. Our findings suggest that much of the reduced fertility in these mice originates from decreased fertilization due to inadequate sperm transport within the female reproductive tract. However, our data indicate that additional reproductive phenotypes in the CF female mice also contribute to the reduced fertility including small ovarian and uterine size, aberrant estrous cycles, and decreased oocyte ovulation rates. These data, along with previous work demonstrating that the gene mutated in CF, the cystic fibrosis transmembrane conductance regulator (CFTR), is normally expressed in tissues vital to reproduction, raises the possibility that CFTR may have a direct effect on fertility. If so, CFTR may also play an important role in normal female fertility within the general population.