Guest editorial: 11th international meeting on rapid responses to steroid hormones RRSH2018

The RRSH 2018 Meeting was the 20th Year Anniversary meeting in the RRSH series begun in Mannheim in 1998. The Meeting brought together a select group of 75 leading experts from the USA, Canada, Europe, China, the Middle and Far East, and Chile. The speakers included senior scientists, clinicians, young researchers and students interested in rapid biological responses to steroid hormones. Lectures and discussions covered the latest developments in research related to molecular and cellular mechanisms of RRSH and its translation to physiology and pathophysiology. The Meeting proceedings published in this Special Issue RRSH2018 of Steroids include reviews and original research RRSH in endocrinology, metabolism, neuroscience, reproduction, cancer, inflammation and cardiovascular disease. Many of the papers highlight the tight reciprocal coupling between ‘non-genomic’ and ‘genomic’ steroid hormone actions. The Meeting was held at the Royal College of Surgeons in Ireland located in the historic 2,000 year old city centre of Dublin. The RRSH2018 Meeting website www.rrsh2018.com hosts a comprehensive overview of lectures, publications and history of RRSH </p

Estrogen-induced signalling and the renal contribution to salt and water homeostasis

The kidney is considered to be one of the most estrogen-responsive, not reproductive organs in the body. Different estrogen receptors (ERs) show sex-specific differences in expression along the nephron and the expression of different ERs also changes with the estrous cycle of the female. The kidney becomes more estrogen-sensitive when estradiol levels are at their highest, just prior to ovulation. This review discusses the different mechanisms by which estradiol can modify the salt and water conservation processes of the kidney through transporter regulation to support the fluid and electrolyte homeostasis changes required in mammalian reproduction. The kidney plays a critical role in regulating blood pressure by controlling fluid homeostasis, and so protects the female cardiovascular system from dramatic changes in whole body fluid volume that occur at critical points in the human menstrual cycle and in pregnancy. This is augmented by the direct actions of estradiol on the cardiovascular system, for example through the direct stimulation of endothelial nitric oxide (NO) synthase, which releases NO to promote vasodilation. This and other mechanisms are less evident in the male and give women a degree of cardiovascular protection up until menopause, when the risks of cardiovascular disease and chronic kidney disease begin to match the risks experienced by males. </p

Sex differences in colon cancer: genomic and nongenomic signalling of oestrogen

Colon cancer (CRC) is a prevalent malignancy that exhibits distinct differences in incidence, prognosis, and treatment responses between males and females. These disparities have long been attributed to hormonal differences, particularly the influence of oestrogen signalling. This review aims to provide a comprehensive analysis of recent advances in our understanding of the molecular mechanisms underlying sex differences in colon cancer and the protective role of membrane and nuclear oestrogen signalling in CRC development, progression, and therapeutic interventions. We discuss the epidemiological and molecular evidence supporting sex differences in colon cancer, followed by an exploration of the impact of oestrogen in CRC through various genomic and nongenomic signalling pathways involving membrane and nuclear oestrogen receptors. Furthermore, we examine the interplay between oestrogen receptors and other signalling pathways, in particular the Wnt/β-catenin proliferative pathway and hypoxia in shaping biological sex differences and oestrogen protective actions in colon cancer. Lastly, we highlight the potential therapeutic implications of targeting oestrogen signalling in the management of colon cancer and propose future research directions to address the current gaps in our understanding of this complex phenomenon.</p

Estrogen-induced signalling and the renal contribution to salt and water homeostasis

The kidney is considered to be one of the most estrogen-responsive, not reproductive organs in the body. Different estrogen receptors (ERs) show sex-specific differences in expression along the nephron and the expression of different ERs also changes with the estrous cycle of the female. The kidney becomes more estrogen-sensitive when estradiol levels are at their highest, just prior to ovulation. This review discusses the different mechanisms by which estradiol can modify the salt and water conservation processes of the kidney through transporter regulation to support the fluid and electrolyte homeostasis changes required in mammalian reproduction. The kidney plays a critical role in regulating blood pressure by controlling fluid homeostasis, and so protects the female cardiovascular system from dramatic changes in whole body fluid volume that occur at critical points in the human menstrual cycle and in pregnancy. This is augmented by the direct actions of estradiol on the cardiovascular system, for example through the direct stimulation of endothelial nitric oxide (NO) synthase, which releases NO to promote vasodilation. This and other mechanisms are less evident in the male and give women a degree of cardiovascular protection up until menopause, when the risks of cardiovascular disease and chronic kidney disease begin to match the risks experienced by males. </p

Dexamethasone reduces airway epithelial Cl- secretion by rapid non-genomic inhibition of KCNQ1, KCNN4 and KATP K+ channels

Basolateral membrane K+ channels play a key role in basal and agonist stimulated Cl− transport across airway epithelial cells by generating a favourable electrical driving force for Cl− efflux. The K+ channel sub-types and molecular mechanisms of regulation by hormones and secretagoues are still poorly understood. Here we have identified the type of K+ channels involved in cAMP and Ca2+ stimulated Cl− secretion and uncovered a novel anti-secretory effect of dexamethasone mediated by inhibition of basolateral membrane K+ channels in a human airway cell model of 16HBE14o− cells commonly used for ion transport studies. Dexamethasone produced a rapid inhibition of transepithelial chloride ion secretion under steady state conditions and after stimulation with cAMP agonist (forskolin) or a Ca2+ mobilizing agonist (ATP). Our results show three different types of K+ channels are targeted by dexamethasone to reduce airway secretion, namely Ca2+-activated secretion via KCNN4 (KCa3.1) channels and cAMP-activated secretion via KCNQ1 (Kv7.1) and KATP (Kir6.1,6.2) channels. The down-regulation of KCNN4 and KCNQ1 channel activities by dexamethasone involves rapid non-genomic activation of PKCα and PKA signalling pathways, respectively. Dexamethasone signal transduction for PKC and PKA activation was demonstrated to occur through a rapid non-genomic pathway that did not implicate the classical nuclear receptors for glucocorticoids or mineralocorticoids but occurred via a novel signalling cascade involving sequentially a Gi-protein coupled receptor, PKC, adenylyl cyclase Type IV, cAMP, PKA and ERK1/2 activation. The rapid, non-genomic, effects of dexamethasone on airway epithelial ion transport and cell signalling introduces a new paradigm for glucocorticoid actions in lung epithelia which may serve to augment the anti-inflammatory activity of the steroid and enhance its therapeutic potential in treating airway hypersecretion in asthma and COPD

Sexual dimorphism in the microbiology of the CF ‘gender gap’: estrogen modulation of pseudomonas aeruginosa virulence

There is increasing evidence for sexual dimorphism of estrogen (E2) actions in the exacerbation of lung function, infection and inflammation in females with cystic fibrosis - the so-called “CF gender gap”. The effects of estrogen on virulence factors that enhance P. aeruginosa persistence in CF lung epithelium were investigated by phenotypic and chemical assays in various PsA clinical isolates and laboratory strains in isolation or in co-culture with normal (Nuli-1) and CF dPhe508-CFTR (CuFi-1) human bronchial epithelial cell lines. Estrogen (E2, 10 nM) significantly increased secretion of the virulence factor pyocyanin by 80% in PsA early infection isolates from female CF patients and by 280% in late infection PsA isolates. Estrogen also increased the swarming motility by up to 50% in all PsA isolates and strains tested in 0.5% agar. A significant increase of 110% in the twitching motility of all PsA isolates and strains tested was also observed with estrogen treatment. Treatment with E2 increased biofilm formation of P. aeruginosa PsAO1 which became more adherent to, and invasive into, normal and CF bronchial epithelial cells. The selective estrogen receptor modulators (SERMs), Tamoxifen and ICI 182780 inhibited P. aeruginosa motility. The potency of various steroid hormones to stimulate motility of P. aeruginosa was in the order; estradiol ≫ estrone > E3 estriol ≥ testosterone ≥ progesterone ≫ aldosterone, cortisol. Estrogen was also shown to reduce ciliary beat intensity in CF bronchial epithelium which would further exacerbate PsA trapping and virulence in the CF airways. In conclusion, we have demonstrated for the first time that estrogen exacerbates P. aeruginosa virulence factors and enhances bacterial interactions with CF bronchial epithelium which can be inhibited by tamoxifen. Our work suggests that SERMs could be used as an adjuvant treatment to reduce estrogen-induced P. aeruginosa infections and associated lung exacerbations in females with CF

Dataset of KCNQ1, KCNN4, KATP channel expression and dexamethasone modulation of protein kinase signaling in airway epithelial cells

Dexamethasone produces anti-secretory responses in airway epithelium through the inhibition of basolateral membrane K+ channels [1–3]. We have used the human bronchial epithelial cell line 16HBE14o− to investigate the effects of dexamethasone on the expression of K+ channels and regulatory protein kinases. The data demonstrate the expression of three distinct K+ channel types – KCNQ1:KCNE3, KCNN4 and KATP which are differentially regulated by protein kinase A and protein kinase C. The data also provide evidence for rapid non-genomic actions of dexamethasone on PKC and PKA phosphorylation and their association with the various K+ channel sub-types. Biotinylation experiments provide data on the effects of dexamethasone on membrane expression of the K+ channels. Antibody co-immunoprecipitation, rtPCR and western blotting data are given for the non-genomic dexamethasone transcription-cell signaling pathway involving Gi-protein coupled receptor, PKC, adenylyl cyclase Type IV, cAMP, PKA and ERK1/2 activation

Ursodeoxycholic acid inhibits ENaC and Na/K pump activity to restore airway surface liquid height in cystic fibrosis bronchial epithelial cells

Cystic fibrosis (CF) is a disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) that in the airways result in reduced Cl− secretion and increased Na+ absorption, airway surface liquid (ASL) dehydration, decreased mucociliary clearance, infection and inflammation leading to lung injury. Cystic fibrosis patients often present with bile acids in the lower airways, however the effects of bile acids on ASL and ion transport in CF airways are not known. Secondary bile acids, such as ursodeoxycholic acid (UDCA), have been shown to modulate immune responses and epithelial ion transport. Here we investigated the effects of UDCA in normal and CF airway epithelial cell models. NuLi-1 (normal genotype) and CuFi-1 (CF genotype, Δ508/Δ508) primary immortalized airway epithelial cells were grown under an air-liquid interface. Electrogenic transepithelial ion transport was measured by short-circuit current (Isc) across cell monolayers mounted in Ussing chambers. We observed that UDCA (500 μM, 60 min, bilateral) decreased the basal Isc and ENaC currents in both NuLi-1 and CuFi-1 cells. UDCA inhibited the amiloride-sensitive ENaC current by 44% in NulI-1 monolayers and by 30% in CuFi-1 cells. Interestingly, UDCA also inhibited currents through the basolateral Na/K pump in both Nuli-1 and CuFi-1 monolayers without alterting the expression of ENaC or Na+/K+-ATPase proteins. The airway surface liquid height is regulated by transpeithelial Na+ absorption (ENaC) and Cl− secretion (CFTR) in normal airway but mainly by ENaC activity in CF epithelia when Cl− secretion is compromised by CFTR mutations. UDCA increased ASL height by 50% in Nuli-1 and by 40% in CUFI-1 monolayers. In conclusion, we demonstrate a previously unknown effect of UDCA to inhibit ENaC activity and increase ASL height in normal and CF human airway epithelial cells suggesting a therapeutic potential for UDCA in CF lung disease

Estrogen inhibits chloride secretion caused by cholera and Escherichia coli enterotoxins in female rat distal colon.

Excessive Cl(-) secretion is the driving force for secretory diarrhea. 17β-Estradiol has been shown to inhibit Cl(-) secretion in rat distal colon through a nongenomic pathway. We examined whether 17β-estradiol inhibits Cl(-) secretion in an animal model of secretory diarrhea and the downstream effectors involved. The effect of 17β-estradiol on cholera toxin and heat-stable enterotoxin induced Cl(-) secretion in rat colonic mucosal sheets was studied by current-voltage clamping. Selective permeabilization of apical or basolateral membranes with amphotericin B or nystatin was used to isolate basolateral K(+) channel and apical Cl(-) channel activity, respectively. 17β-Estradiol dose-dependently inhibited secretory responses to both toxins with IC(50) values of approximately 1nM. This effect was female-gender specific, with no inhibition observed in male tissues. 17β-Estradiol responses were insensitive to the pure anti-estrogen ICI 182,720. 17β-Estradiol exerted its effects downstream of enterotoxin-induced production of second messengers (cAMP and cGMP) but was dependent on PKCδ activation. In nystatin-permeabilized tissues, apical Cl(-) currents were unaffected by 17β-estradiol treatment while basolateral K(+) current was profoundly inhibited by the hormone. This current was sensitive to the specific KCNQ1 channel inhibitors chromanol 293B and HMR-1556. In conclusion, 17β-estradiol inhibits enterotoxin-induced Cl(-) secretion via a PKCδ-dependent mechanism involving inhibition of basolateral KCNQ1 channels. These data elucidate mechanisms of 17β-estradiol inhibition of Cl(-) secretion induced by enterotoxins in intestinal epithelia, which may be relevant for the treatment of diarrheal diseases.</p

Protein kinase D stabilizes aldosterone-induced ERK1/2 MAP kinase activation in M1 renal cortical collecting duct cells to promote cell proliferation.

Aldosterone elicits transcriptional responses in target tissues and also rapidly stimulates the activation of protein kinase signalling cascades independently of de novo protein synthesis. Here we investigated aldosterone-induced cell proliferation and extra-cellular regulated kinase 1 and 2 (ERK1/2) mitogen activated protein (MAP) kinase signalling in the M1 cortical collecting duct cell line (M1-CCD). Aldosterone promoted the proliferative growth of M1-CCD cells, an effect that was protein kinase D1 (PKD1), PKCdelta and ERK1/2-dependent. Aldosterone induced the rapid activation of ERK1/2 with peaks of activation at 2 and 10 to 30 min after hormone treatment followed by sustained activation lasting beyond 120 min. M1-CCD cells suppressed in PKD1 expression exhibited only the early, transient peaks in ERK1/2 activation without the sustained phase. Aldosterone stimulated the physical association of PKD1 with ERK1/2 within 2 min of treatment. The mineralocorticoid receptor (MR) antagonist RU28318 inhibited the early and late phases of aldosterone-induced ERK1/2 activation, and also aldosterone-induced proliferative cell growth. Aldosterone induced the sub-cellular redistribution of ERK1/2 to the nuclei at 2 min and to cytoplasmic sites, proximal to the nuclei after 30 min. This sub-cellular distribution of ERK1/2 was inhibited in cells suppressed in the expression of PKD1