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Paul E Micevych - One of the best experts on this subject based on the ideXlab platform.
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Nervous system physiology regulated by Membrane Estrogen receptors.
Reviews in The Neurosciences, 2020Co-Authors: Paul G Mermelstein, Paul E MicevychAbstract:The importance of steroid hormones in the regulation of nervous system function cannot be overstated. Estrogens, in particular, have profound effects on a variety of neurological systems. The most obvious actions include those that are related to sexual differentiation of the brain (Gorski, 1985) and the central control of reproduction (Pfaff et al., 2000). More recently, estradiol has been shown to be critical in a number of cellular events, such as neuronal growth and restructuring, that impact cognition, long-term potentiation, neuroprotection and mood (Belcredito et al., 2001; Lee and McEwen, 2001; Smith and McMahon, 2005). While the impact of Estrogens on these behaviors has been well characterized, the underlying mechanism(s) through which the steroid acts to affect many of these processes remains to be elucidated. It was once accepted that the only mechanism of Estrogen action was through the binding of intracellular receptors that act as transcription factors. An important finding that has enhanced our understanding of estradiol action was the realization that estradiol can also act on Estrogen receptors (ERs) localized at the cellular Membrane surface. This is in distinction to the classical actions of Estrogens, which typically have long time courses and involve gene transcription and protein translation. Classic actions are mediated by Estrogen receptor-α (ERα) and Estrogen receptor-β (ERβ). Upon steroid binding, these receptors dimerize, allowing them to functionally interact with specific parts of the genome known as Estrogen response elements (EREs) to regulate gene expression. Activated Estrogen receptors can also regulate transcription through the stabilization of other DNA binding proteins such as those that interact with activator protein 1 (AP-1) (Kushner et al., 2000; Paech et al., 1997; Webb et al., 1999).
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A Novel Membrane Estrogen Receptor Activated by STX Induces Female Sexual Receptivity through an Interaction with mGluR1a.
Neuroendocrinology, 2013Co-Authors: Amy Christensen, Paul E MicevychAbstract:Membrane initiated estradiol signaling has been shown to be vital for multiple physiological processes. Several receptors have been proposed to mediate the actions of estradiol at the Membrane. Here, we examined the ability of STX, an agonist of a novel putative Membrane Estrogen receptor, to activate sexually receptive behavior in the female rat. Infusions of STX into the arcuate nucleus of the hypothalamus resulted in the activation and internalization of μ-opioid receptors in the medial preoptic nucleus, an action that is required for lordosis behavior. Indeed, STX was able to augment sexual receptivity in female rats given a sub-behavioral dose of estradiol. However, if the mGluR1a antagonist, LY367,385, was administered prior to STX, its circuit-activating effects, the internalization of μ-opioid receptors, were lost. This suggests that the receptor stimulated by STX activates rapid Membrane-initiated signaling through an interaction with mGluR1a – an effect previously described for Estrogen receptor-α at the Membrane.
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cav1 sirna reduces Membrane Estrogen receptor α levels and attenuates sexual receptivity
Endocrinology, 2012Co-Authors: Amy Christensen, Paul E MicevychAbstract:Although classic Estrogen receptors (ER) have been proposed to mediate estradiol signaling, it has been relatively recently that mechanisms of trafficking these receptors have been elucidated. ERα is palmitoylated and associates with caveolin proteins to be targeted to the cell Membrane. Caveolins are scaffold proteins that not only traffic ERα to the Membrane but also are involved in establishing metabotropic glutamate receptor interactions that are necessary for activating G protein signaling. To demonstrate the role of caveolin proteins in regulating an estradiol-dependent behavior, sexual receptivity, we used small interfering RNA to knock down caveolin-1 (CAV1) expression in the arcuate nucleus of the hypothalamus. In CAV1 knockdown rats, Membrane, but not intracellular levels of ERα, were significantly reduced. As expected, Estrogenic stimulation of the arcuate nucleus of the hypothalamus to medial preoptic nucleus projection was abrogated in CAV1 knockdown rats, indicating that the Membrane-initiated activation of this circuit was compromised. Moreover, estradiol-induced lordosis behavior that is dependent on activation of μ-opioid receptors in the medial preoptic nucleus was also significantly reduced. Thus, CAV1-mediated ERα trafficking to the cell Membrane is required for estradiol activation of circuits underlying female sexual receptivity.
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Membrane Estrogen receptor regulation of hypothalamic function
Neuroendocrinology, 2012Co-Authors: Paul E Micevych, Martin J KellyAbstract:Over the decades, our understanding of Estrogen receptor (ER) function has evolved. Today we are confronted by at least two nuclear ERs, ERα and ERβ, and a number of putative Membrane ERs, including ERα, ERβ, ER-X, GPR30 and Gq-mER. These receptors all bind Estrogens or at least Estrogenic compounds and activate intracellular signaling pathways. In some cases, a well-defined pharmacology and physiology has been discovered. In other cases, the identity or the function remains to be elucidated. This mini-review attempts to synthesize our understanding of 17β-estradiol Membrane signaling within hypothalamic circuits involved in homeostatic functions, focusing on reproduction and energy balance.
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Membrane Estrogen receptors stimulate intracellular calcium release and progesterone synthesis in hypothalamic astrocytes
The Journal of Neuroscience, 2010Co-Authors: Naheed Hamid, Galyna Bondar, Eric R Prossnitz, Paul E MicevychAbstract:In hypothalamic astrocytes obtained from adult female rats, estradiol rapidly increased free cytoplasmic calcium concentrations ([Ca 2+ ] i ) that facilitate progesterone synthesis. The present study demonstrated that estradiol (1 nm) significantly and maximally stimulated progesterone synthesis within 5 min, supporting a rapid, nongenomic mechanism. The group I metabotropic glutamate receptor (mGluR1a) antagonist LY 367385 [( S )-(+)-a-amino-4-carboxy-2-methylbenzeneacetic acid] attenuated both the estradiol-induced [Ca 2+ ] i release and progesterone synthesis. To investigate Membrane-associated Estrogen receptors (mERs), agonists for ERα, ERβ, STX-activated protein, and GPR30 were compared. The selective ERα agonist propylpyrazole triole (PPT) and STX most closely mimicked the estradiol-induced [Ca 2+ ] i responses, where PPT was more potent but less efficacious than STX. Only high doses (100 nm) of selective ERβ agonist diarylpropionitrile (DPN) and GPR30 agonist G-1 induced estradiol-like [Ca 2+ ] i responses. With the exception of DPN (even at 100 nm), all agonists stimulated progesterone synthesis. The PPT- and STX-induced [Ca 2+ ] i release and progesterone synthesis were blocked by LY 367385. While the G-1-stimulated [Ca 2+ ] i release was blocked by LY 367385, progesterone synthesis was not. Since GPR30 was detected intracellularly but not in the Membrane, we interpreted these results to suggest that G-1 could activate mGluR1a on the Membrane and GPR30 on the smooth endoplasmic reticulum to release intracellular calcium. Although STX and G-1 maximally stimulated [Ca 2+ ] i release in astrocytes from Estrogen receptor-α knock-out (ERKO) mice, estradiol in vivo did not stimulate progesterone synthesis in the ERKO mice. Together, these results indicate that mERα is mainly responsible for the rapid, Membrane-initiated estradiol-signaling that leads to progesterone synthesis in hypothalamic astrocytes.
Martin J Kelly - One of the best experts on this subject based on the ideXlab platform.
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the Membrane Estrogen receptor ligand stx rapidly enhances gabaergic signaling in npy agrp neurons role in mediating the anorexigenic effects of 17β estradiol
American Journal of Physiology-endocrinology and Metabolism, 2013Co-Authors: Arik W Smith, Martin J Kelly, Oline K. Rønnekleiv, Martha A Bosch, Edward J WagnerAbstract:Besides its quintessential role in reproduction, 17β-estradiol (E2) is a potent anorexigenic hormone. E2 and the selective Gq-coupled Membrane Estrogen receptor (Gq-mER) ligand STX rapidly increase Membrane excitability in proopiomelanocortin (POMC) neurons by desensitizing the coupling of GABAB receptors to G protein-coupled inwardly rectifying K+ channels (GIRKs), which upon activation elicit a hyperpolarizing outward current. However, it is unknown whether E2 and STX can modulate GABAB signaling in neuropeptide Y (NPY)/agouti-related peptide (AgRP) neurons. We used single-cell RT-PCR and whole cell patch clamping with selective pharmacological reagents to show that NPY/AgRP cells of mice express the GABAB-R1 and -R2 receptors and are hyperpolarized by the GABAB agonist baclofen in an E2-dependent manner. In males, E2 rapidly attenuated the coupling of GABAB receptors to GIRKs, which was blocked by the general PI3K inhibitors wortmannin and LY-294002 or the selective p110β subunit inhibitor TGX-221. The ERα-selective agonist propyl pyrazole triol mimicked the effects of E2. STX, in contrast, enhanced the GABAB response in males, which was abrogated by the Estrogen receptor (ER) antagonist ICI 182,780. In gonadectomized mice of both sexes, E2 enhanced or attenuated the GABAB response in different NPY/AgRP cells. Coperfusing wortmannin with E2 or simply applying STX always enhanced the GABAB response. Thus, in NPY/AgRP neurons, activation of the Gq-mER by E2 or STX enhances the GABAergic postsynaptic response, whereas activation of ERα by E2 attenuates it. These findings demonstrate a clear functional dichotomy of rapid E2 Membrane-initiated signaling via ERα vs. Gq-mER in a CNS neuron vital for regulating energy homeostasis.
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The Membrane Estrogen receptor ligand STX rapidly enhances GABAergic signaling in NPY/AgRP neurons: role in mediating the anorexigenic effects of 17β-estradiol.
American Journal of Physiology-endocrinology and Metabolism, 2013Co-Authors: Arik W Smith, Oline K. Rønnekleiv, Martha A Bosch, Edward J Wagner, Martin J KellyAbstract:Besides its quintessential role in reproduction, 17β-estradiol (E2) is a potent anorexigenic hormone. E2 and the selective Gq-coupled Membrane Estrogen receptor (Gq-mER) ligand STX rapidly increase Membrane excitability in proopiomelanocortin (POMC) neurons by desensitizing the coupling of GABAB receptors to G protein-coupled inwardly rectifying K+ channels (GIRKs), which upon activation elicit a hyperpolarizing outward current. However, it is unknown whether E2 and STX can modulate GABAB signaling in neuropeptide Y (NPY)/agouti-related peptide (AgRP) neurons. We used single-cell RT-PCR and whole cell patch clamping with selective pharmacological reagents to show that NPY/AgRP cells of mice express the GABAB-R1 and -R2 receptors and are hyperpolarized by the GABAB agonist baclofen in an E2-dependent manner. In males, E2 rapidly attenuated the coupling of GABAB receptors to GIRKs, which was blocked by the general PI3K inhibitors wortmannin and LY-294002 or the selective p110β subunit inhibitor TGX-221. The ERα-selective agonist propyl pyrazole triol mimicked the effects of E2. STX, in contrast, enhanced the GABAB response in males, which was abrogated by the Estrogen receptor (ER) antagonist ICI 182,780. In gonadectomized mice of both sexes, E2 enhanced or attenuated the GABAB response in different NPY/AgRP cells. Coperfusing wortmannin with E2 or simply applying STX always enhanced the GABAB response. Thus, in NPY/AgRP neurons, activation of the Gq-mER by E2 or STX enhances the GABAergic postsynaptic response, whereas activation of ERα by E2 attenuates it. These findings demonstrate a clear functional dichotomy of rapid E2 Membrane-initiated signaling via ERα vs. Gq-mER in a CNS neuron vital for regulating energy homeostasis.
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A selective Membrane Estrogen receptor agonist maintains autonomic functions in hypoEstrogenic states.
Brain Research, 2013Co-Authors: Martin J Kelly, Oline K. RønnekleivAbstract:Abstract It is well known that many of the actions of Estrogens in the central nervous system are mediated via intracellular receptor/transcription factors that interact with steroid response elements on target genes. But there is also a compelling evidence for the involvement of Membrane Estrogen receptors in hypothalamic and other CNS functions. However, it is not well understood how Estrogens signal via Membrane receptors, and how these signals impact not only Membrane excitability but also gene transcription in neurons. Indeed, it has been known for sometime that Estrogens can rapidly alter neuronal activity within seconds, indicating that some cellular effects can occur via Membrane delimited events. In addition, Estrogens can affect second messenger systems including calcium mobilization and a plethora of kinases within neurons to alter cellular functions. Therefore, this brief review will summarize our current understanding of rapid Membrane-initiated and intracellular signaling by Estrogens in the hypothalamus, the nature of receptors involved and how these receptors contribute to maintenance of homeostatic functions, many of which go awry in menopausal states. This article is part of a Special Issue entitled Hormone Therapy .
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Membrane Estrogen receptor regulation of hypothalamic function
Neuroendocrinology, 2012Co-Authors: Paul E Micevych, Martin J KellyAbstract:Over the decades, our understanding of Estrogen receptor (ER) function has evolved. Today we are confronted by at least two nuclear ERs, ERα and ERβ, and a number of putative Membrane ERs, including ERα, ERβ, ER-X, GPR30 and Gq-mER. These receptors all bind Estrogens or at least Estrogenic compounds and activate intracellular signaling pathways. In some cases, a well-defined pharmacology and physiology has been discovered. In other cases, the identity or the function remains to be elucidated. This mini-review attempts to synthesize our understanding of 17β-estradiol Membrane signaling within hypothalamic circuits involved in homeostatic functions, focusing on reproduction and energy balance.
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rapid actions of plasma Membrane Estrogen receptors
Trends in Endocrinology and Metabolism, 2001Co-Authors: Martin J Kelly, Ellis R. LevinAbstract:Abstract Functional evidence for the existence of plasma Membrane Estrogen receptors in a variety of cell types continues to accumulate. Many of these functions originate from rapid signaling events, transduced in response to 17β-estradiol (E 2 ). It has been convincingly shown that E 2 activates phosphoinositol 3-kinase and protein kinase B/AKT, and stimulates ERK and p38 MAP kinases. In part, this stems from G-protein activation and the resulting calcium flux. As a result, the link between E 2 action at the cell Membrane and discrete biological actions in the cell has been strengthened. There is now convincing in vitro evidence that E 2 can modulate the functions of neural and vascular cells via non-genomic actions. Thus, the actions of discrete pools of E 2 receptors are likely to contribute to the overall effects of the sex steroids.
Ellis R. Levin - One of the best experts on this subject based on the ideXlab platform.
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Role of the Membrane Estrogen Receptor in Vascular Cell Physiology
Biology of Menopause, 2020Co-Authors: Ellis R. LevinAbstract:Estrogen’s cellular actions are felt to be mediated through response elements on the promoters of target genes, or through modifying transcription via protein-protein interactions (1–4). There is increasing evidence, however, that ligands for various members of the steroid receptor superfamily modulate cell functions via nongenomic actions. Some of these actions appear to originate through plasma Membrane protein interactions (5–8). As examples of nongenomic functions, progesterone quickly stimulates increased [Ca2+]i in sperm (6), and aldosterone rapidly activates inositol1,4,5-trisphosphate generation in several cell types (8), or stimulates hemodynamic changes quickly (9). 17β-Estradiol (17βE2) can induce various signal transduction events in seconds to a few minutes. These events include the stimulation of calcium flux (10), cAMP (11), phospholipase C activation, and inositol phosphate generation (12,13), as well as the rapid release of prolactin (14). Many of the rapid actions of 17β-E2 have been attributed to interactions at the cell Membrane. These could include 17β-E2 indirectly activating tyrosine kinase growth factor receptors (e.g., epidermal growth factor receptor, EGFR), with subsequent signal transduction initiated through these receptors (15). On the other hand, the existence of a cell Membrane Estrogen receptor (ER) was reported more than 20 years ago (16).
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Membrane Estrogen receptors signal to determine transcription factor function.
Steroids, 2017Co-Authors: Ellis R. LevinAbstract:Abstract Estrogen receptors (ER) alpha and beta as well as many other steroid receptors are found both within the nucleus and outside the nucleus. This includes extra-nuclear receptors in many organelles, including mitochondria, endoplasmic reticulum, cytosolic endosomes, and Membrane lipid rafts, such as caveolae. The functions of these receptors in the various extra-nuclear cell organelles are not well described, but progress for understanding steroid receptor signaling from the Membrane has advanced. In this Review I will discuss the enlarging role of Membrane ER signaling to the expression, cell localization, and function of transcription factors that are essential to mediate cell physiology or pathophysiology in many organs.
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plasma Membrane Estrogen receptors
Trends in Endocrinology and Metabolism, 2009Co-Authors: Ellis R. LevinAbstract:It is now firmly established that Estrogen and all sex steroid receptors exist in discrete cellular pools outside the nucleus. Estrogen receptors (ER) have been localized to the plasma Membrane where both ERα and ERβ function in a wide variety of cells and organs. ERs have also been found in discrete cytoplasmic organelles including mitochondria and the endoplasmic reticulum. In ligand-dependent fashion, each ER pool contributes to the overall, integrated effects of Estrogens producing biological outcomes. This review highlights the recent work establishing new roles and targets of Membrane ER signaling. Such actions include prevention of vascular injury or cardiac hypertrophy, sexual behavior and pain perception mediated through the central nervous system, osteoblast survival, and fluid resorption in the colon.
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plasma Membrane Estrogen receptors exist and functions as dimers
Molecular Endocrinology, 2004Co-Authors: Mahnaz Razandi, Ali Pedram, Istvan Merchenthaler, Geoffrey L Greene, Ellis R. LevinAbstract:A small pool of Estrogen receptors (ERα and -β) localize at the plasma Membrane and rapidly signal to affect cellular physiology. Although nuclear ERs function mainly as homodimers, it is unknown whether Membrane-localized ER exists or functions with similar requirements. We report that the endogenous ER isoforms at the plasma Membrane of breast cancer or endothelial cells exist predominantly as homodimers in the presence of 17β-estradiol (E2). Interestingly, in endothelial cells made from ERα /ERβ homozygous double-knockout mice, Membrane ERα or ERβ are absent, indicating that the endogenous Membrane receptors derive from the same gene(s) as the nuclear receptors. In ER-negative breast cancer cells or Chinese hamster ovary cells, we expressed and compared wild-type and dimer mutant mouse ERα. Only wild-type ERα supported the ability of E2 to rapidly activate ERK, cAMP, and phosphatidylinositol 3-kinase signaling. This resulted from E2 activating Gsα and Gqα at the Membrane in cells expressing the wild-ty...
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brca1 inhibits Membrane Estrogen and growth factor receptor signaling to cell proliferation in breast cancer
Molecular and Cellular Biology, 2004Co-Authors: Mahnaz Razandi, Ali Pedram, Eliot M Rosen, Ellis R. LevinAbstract:BRCA1 mutations and Estrogen use are risk factors for the development of breast cancer. Recent work has identified Estrogen receptors localized at the plasma Membrane that signal to cell biology. We examined the impact of BRCA1 on Membrane Estrogen and growth factor receptor signaling to breast cancer cell proliferation. MCF-7 and ZR-75-1 cells showed a rapid and sustained activation of extracellular signal-related kinase (ERK) in response to estradiol (E2) that was substantially prevented by wild-type (wt) but not mutant BRCA1. The proliferation of MCF-7 cells induced by E2 was significantly inhibited by PD98059, a specific ERK inhibitor, or by dominant negative ERK2 expression and by expression of wt BRCA1 (but not mutant BRCA1). E2 induced the synthesis of cyclins D1 and B1, the activity of cyclin-dependent kinases Cdk4 and CDK1, and G1/S and G2/M cell cycle progression. The intact tumor suppressor inhibited all of these. wt BRCA1 also inhibited epidermal growth factor and insulin-like growth factor I-induced ERK and cell proliferation. The inhibition of ERK and cell proliferation by BRCA1 was prevented by phosphatase inhibitors and by interfering RNA knockdown of the ERK phosphatase, mitogen-activated kinase phosphatase 1. Our findings support a novel tumor suppressor function of BRCA1 that is relevant to breast cancer and identify a potential interactive risk factor for women with BRCA1 mutations.
Cheryl S Watson - One of the best experts on this subject based on the ideXlab platform.
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Proliferative and anti-proliferative effects of dietary levels of phytoEstrogens in rat pituitary GH3/B6/F10 cells - the involvement of rapidly activated kinases and caspases
BMC Cancer, 2009Co-Authors: Yow Jiun Jeng, Cheryl S WatsonAbstract:Phytoestogens are a group of lipophillic plant compounds that can have Estrogenic effects in animals; both tumorigenic and anti-tumorigenic effects have been reported. Prolactin-secreting adenomas are the most prevalent form of pituitary tumors in humans and have been linked to Estrogen exposures. We examined the proliferative effects of phytoEstrogens on a rat pituitary tumor cell line, GH3/B6/F10, originally subcloned from GH3 cells based on its ability to express high levels of the Membrane Estrogen receptor-α.
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the roles of Membrane Estrogen receptor subtypes in modulating dopamine transporters in pc 12 cells
Journal of Neurochemistry, 2008Co-Authors: Rebecca A Alyea, Stephanie E Laurence, Benita S Katzenellenbogen, John A Katzenellenbogen, Cheryl S WatsonAbstract:The effects of 17β-estradiol (E2) on dopamine (DA) transport could explain gender and life-stage differences in the incidence of some neurological disorders. We tested the effects of E2 at physiological concentrations on DA efflux in nerve growth factor-differentiated rat pheochromocytoma cells that express Estrogen receptors (ER) α, ERβ, and G-protein coupled receptor 30 (GPR30), and DA transporter (DAT). DAT efflux was determined as the transporter-specific loss of 3H-DA from pre-loaded cells; a 9–15 min 10−9 M E2 treatment caused maximal DA efflux. Such rapid Estrogenic action suggests a non-genomic response, and an E2-dendrimer conjugate (limited to non-nuclear actions) caused DA efflux within 5 min. Efflux dose–responses for E2 were non-monotonic, also characteristic of non-genomic Estrogenic actions. ERα siRNA knockdown abolished E2-mediated DA efflux, while ERβ knockdown did not, and GPR30 knockdown increased E2-mediated DA efflux (suggesting GPR30 is inhibitory). Use of ER-selective agonists/antagonists demonstrated that ERα is the predominant mediator of E2-mediated DA efflux, with inhibitory contributions from GPR30 and ERβ. E2 also caused trafficking of ERα to the plasma Membrane, trafficking of ERβ away from the plasma Membrane, and unchanged Membrane GPR30 levels. Therefore, ERα is largely responsible for non-genomic Estrogenic effects on DAT activity.
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signaling from the Membrane via Membrane Estrogen receptor α Estrogens xenoEstrogens and phytoEstrogens
Steroids, 2005Co-Authors: Cheryl S Watson, Nataliya N Bulayeva, Ann L Wozniak, Celeste C FinnertyAbstract:Abstract Estrogen mimetics in the environment and in foods can have important consequences for endocrine functions. When previously examined for action via genomic steroid signaling mechanisms, most of these compounds were found to be very weak agonists. We have instead tested their actions via several Membrane-initiated signaling mechanisms in GH3/B6 pituitary tumor cells extensively selected for high (responsive) or low (nonresponsive) expression of the Membrane version of Estrogen receptor-α (mERα). We found many Estrogen mimetic compounds to be potently active in our quantitative extracellular-regulated kinase (ERK) activation assays, to increase cellular Ca++ levels, and to cause rapid prolactin release. However, these compounds may activate one or both mechanisms with different potencies. For instance, some compounds activate ERKs in both pM and nM concentration ranges, while others are only active at nM and higher concentrations. Compounds also show great differences in their temporal activation patterns. While estradiol causes a bimodal time-dependent ERK activation (peaking at both 3 and 30 min), most Estrogen mimetics cause either an early phase activation, a late phase activation, or an early sustained activation. One xenoEstrogen known to be a relatively potent activator of Estrogen response element-mediated actions (bisphenol A) is inactive as an ERK activator, and only a modest inducer of Ca++ levels and prolactin release. Many different signaling machineries culminate in ERK activation, and xenoEstrogens differentially affect various pathways. Clearly individual xenoEstrogens must be individually investigated for their differing abilities to activate distinct Membrane-initiated signal cascades that lead to a variety of cellular functions.
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xenoEstrogens at picomolar to nanomolar concentrations trigger Membrane Estrogen receptor α mediated ca2 fluxes and prolactin release in gh3 b6 pituitary tumor cells
Environmental Health Perspectives, 2005Co-Authors: Ann L Wozniak, Nataliya N Bulayeva, Cheryl S WatsonAbstract:XenoEstrogens (XEs) are widespread in our environment and are known to have deleterious effects in animal (and perhaps human) populations. Acting as inappropriate Estrogens, XEs are thought to interfere with endogenous Estrogens such as estradiol (E2) to disrupt normal Estrogenic signaling. We investigated the effects of E2 versus several XEs representing organochlorine pesticides (dieldrin, endosulfan, o′p′-dichlorodiphenylethylene), plastics manufacturing by-products/detergents (nonylphenol, bisphenol A), a phytoEstrogen (coumestrol), and a synthetic Estrogen (diethylstilbestrol) on the pituitary tumor cell subline GH3/B6/F10, previously selected for expression of high levels of Membrane Estrogen receptor-α. Picomolar to nanomolar concentrations of both E2 and XEs caused intracellular Ca2+ changes within 30 sec of administration. Each XE produced a unique temporal pattern of Ca2+ elevation. Removing Ca2+ from the extracellular solution abolished both spontaneous and XE-induced intracellular Ca2+ changes, as did 10 μM nifedipine. This suggests that XEs mediate their actions via voltage-dependent L-type Ca2+ channels in the plasma Membrane. None of the Ca2+ fluxes came from intracellular Ca2+ stores. E2 and each XE also caused unique time- and concentration-dependent patterns of prolactin (PRL) secretion that were largely complete within 3 min of administration. PRL secretion was also blocked by nifedipine, demonstrating a correlation between Ca2+ influx and PRL secretion. These data indicate that at very low concentrations, XEs mediate Membrane-initiated intracellular Ca2+ increases resulting in PRL secretion via a mechanism similar to that for E2, but with distinct patterns and potencies that could explain their abilities to disrupt endocrine functions.
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XenoEstrogens at Picomolar to Nanomolar Concentrations Trigger Membrane Estrogen Receptor-α–Mediated Ca2+ Fluxes and Prolactin Release in GH3/B6 Pituitary Tumor Cells
Environmental Health Perspectives, 2005Co-Authors: Ann L Wozniak, Nataliya N Bulayeva, Cheryl S WatsonAbstract:XenoEstrogens (XEs) are widespread in our environment and are known to have deleterious effects in animal (and perhaps human) populations. Acting as inappropriate Estrogens, XEs are thought to interfere with endogenous Estrogens such as estradiol (E2) to disrupt normal Estrogenic signaling. We investigated the effects of E2 versus several XEs representing organochlorine pesticides (dieldrin, endosulfan, o′p′-dichlorodiphenylethylene), plastics manufacturing by-products/detergents (nonylphenol, bisphenol A), a phytoEstrogen (coumestrol), and a synthetic Estrogen (diethylstilbestrol) on the pituitary tumor cell subline GH3/B6/F10, previously selected for expression of high levels of Membrane Estrogen receptor-α. Picomolar to nanomolar concentrations of both E2 and XEs caused intracellular Ca2+ changes within 30 sec of administration. Each XE produced a unique temporal pattern of Ca2+ elevation. Removing Ca2+ from the extracellular solution abolished both spontaneous and XE-induced intracellular Ca2+ changes, as did 10 μM nifedipine. This suggests that XEs mediate their actions via voltage-dependent L-type Ca2+ channels in the plasma Membrane. None of the Ca2+ fluxes came from intracellular Ca2+ stores. E2 and each XE also caused unique time- and concentration-dependent patterns of prolactin (PRL) secretion that were largely complete within 3 min of administration. PRL secretion was also blocked by nifedipine, demonstrating a correlation between Ca2+ influx and PRL secretion. These data indicate that at very low concentrations, XEs mediate Membrane-initiated intracellular Ca2+ increases resulting in PRL secretion via a mechanism similar to that for E2, but with distinct patterns and potencies that could explain their abilities to disrupt endocrine functions.
Jeffrey R Bender - One of the best experts on this subject based on the ideXlab platform.
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Vascular cell signaling by Membrane Estrogen receptors.
Steroids, 2008Co-Authors: Katie Moriarty, Jeffrey R BenderAbstract:The definition of Estrogen's actions has expanded from transcriptional regulation to the rapid, Membrane-initiated activation of numerous signal transduction cascades. Multiple biological effects of Estrogen have been shown in numerous animals, cellular and molecular studies, which support the favorable effects of Estrogen on vascular structure, function, and cell signaling. Work from several laboratories has shown that these effects are mediated by distinct forms of Estrogen receptor (ER) alpha. This includes Estrogen-stimulated rapid activation of endothelial nitric oxide synthase (eNOS), resulting in the elaboration of the athero-protective, angiogenesis-promoting product nitric oxide (NO). We have described the expression of ER46, an N-terminus truncated isoform of the ERalpha, in human endothelial cells (EC), and its critical role in Membrane-initiated, rapid responses to 17beta-estradiol (E2). We have proposed an ER46-centered, eNOS activating molecular complex in human EC caveolar Membranes, containing c-Src, phosphatidylinositol 3-kinase (PI3K), Akt and eNOS. Our previous studies support Estrogen-induced rapid eNOS activation via a sequential c-Src/PI3K/Akt cascade in EC. In this review, we describe Estrogen-induced, rapid, non-genomic actions in endothelium, driven by c-Src-ER46-caveolin-1 interactions, with consequent activation of eNOS. Amidst ongoing controversies in hormone replacement therapy, these molecular and cellular data, defining favorable Estrogenic effects on the endothelium, provide a strong impetus to resolve these clinical questions.
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vascular cell signaling by Membrane Estrogen receptors
Steroids, 2005Co-Authors: Katie Moriarty, Jeffrey R BenderAbstract:Abstract The definition of Estrogen's actions has expanded from transcriptional regulation to the rapid, Membrane-initiated activation of numerous signal transduction cascades. Multiple biological effects of Estrogen have been shown in numerous animals, cellular and molecular studies, which support the favorable effects of Estrogen on vascular structure, function, and cell signaling. Work from several laboratories has shown that these effects are mediated by distinct forms of Estrogen receptor (ER) α. This includes Estrogen-stimulated rapid activation of endothelial nitric oxide synthase (eNOS), resulting in the elaboration of the athero-protective, angiogenesis-promoting product nitric oxide (NO). We have described the expression of ER46, an N-terminus truncated isoform of the ERα, in human endothelial cells (EC), and its critical role in Membrane-initiated, rapid responses to 17β-estradiol (E2). We have proposed an ER46-centered, eNOS activating molecular complex in human EC caveolar Membranes, containing c-Src, phosphatidylinositol 3-kinase (PI3K), Akt and eNOS. Our previous studies support Estrogen-induced rapid eNOS activation via a sequential c-Src/PI3K/Akt cascade in EC. In this review, we describe Estrogen-induced, rapid, non-genomic actions in endothelium, driven by c-Src-ER46-caveolin-1 interactions, with consequent activation of eNOS. Amidst ongoing controversies in hormone replacement therapy, these molecular and cellular data, defining favorable Estrogenic effects on the endothelium, provide a strong impetus to resolve these clinical questions.
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Vascular cell signaling by Membrane Estrogen receptors.
Steroids, 2005Co-Authors: Koji Hisamoto, Jeffrey R BenderAbstract:There is substantial interest in the effects of Estrogen on the vascular wall, due to the marked gender difference in the incidence of clinically apparent coronary heart disease (CHD), when comparing premenopausal women with age-matched males. Recent randomized clinical trials unexpectedly failed to demonstrate a hormone replacement therapy (HRT) benefit for CHD secondary or primary prevention in postmenopausal women. There are several possible explanations for these findings, which have created a conundrum in light of the numerous potentially beneficial vascular effects of Estrogen demonstrated at the cellular, molecular, and even animal model level. Clinical trials are ongoing, and the dissection of molecular pathways continues. Although Estrogen receptors (ERs) are traditionally defined as ligand-activated transcriptional activators or repressors, a phenomenon certainly involved in some of Estrogen's beneficial effects on vascular cells, we and others have recently demonstrated the presence of Membrane-associated ERs in endothelial cells (EC), and that engagement of this subset of receptors may also contribute to the favorable molecular profile of the endothelium. In this review, we describe evidence for Membrane-localized ERs in EC. We discuss features of their Membrane targeting, and how they may differ from classical ERs. We also describe the rapid assembly of a Membrane-associated molecular complex, comprised of ER, c-Src and the regulatory unit of phosphatidylinositol 3-kinase (PI3K), p85, in response to Estrogen. Finally, we describe how this complex triggers sequential enzyme activation, involving endothelial nitric oxide synthase (eNOS), and consequent enhanced basal release of NO, a key modulator of vascular tone and 'healthy' blood vessels.
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Membrane Estrogen receptor engagement activates endothelial nitric oxide synthase via the pi3 kinase akt pathway in human endothelial cells
Circulation Research, 2000Co-Authors: Page M Haynes, Diviya Sinha, Kerry S Russell, Mark Collinge, David J Fulton, Manuel Moralesruiz, William C Sessa, Jeffrey R BenderAbstract:Abstract —17β-Estradiol (E2) is a rapid activator of endothelial nitric oxide synthase (eNOS). The product of this activation event, NO, is a fundamental determinant of cardiovascular homeostasis. We previously demonstrated that E2-stimulated endothelial NO release can occur without an increase in cytosolic Ca2+. Here we demonstrate for the first time, to our knowledge, that E2 rapidly induces phosphorylation and activation of eNOS through the phosphatidylinositol 3 (PI3)-kinase–Akt pathway. E2 treatment (10 ng/mL) of the human endothelial cell line, EA.hy926, resulted in increased NO production, which was abrogated by the PI3-kinase inhibitor, LY294002, and the Estrogen receptor antagonist ICI 182,780. E2 stimulated rapid Akt phosphorylation on serine 473. As has been shown for vascular endothelial growth factor, eNOS is an E2-activated Akt substrate, demonstrated by rapid eNOS phosphorylation on serine 1177, a critical residue for eNOS activation and enhanced sensitivity to resting cellular Ca2+ levels. Adenoviral-mediated EA.hy926 transduction confirmed functional involvement of Akt, because a kinase-deficient, dominant-negative Akt abolished E2-stimulated NO release. The Membrane-impermeant E2BSA conjugate, shown to bind endothelial cell Membrane sites, also induced rapid Akt and consequent eNOS phosphorylation. Thus, engagement of Membrane Estrogen receptors results in rapid endothelial NO release through a PI3-kinase–Akt-dependent pathway. This explains, in part, the reduced requirement for cytosolic Ca2+ fluxes and describes an important pathway relevant to cardiovascular pathophysiology.
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Membrane Estrogen Receptor Engagement Activates Endothelial Nitric Oxide Synthase via the PI3-Kinase–Akt Pathway in Human Endothelial Cells
Circulation Research, 2000Co-Authors: M. Page Haynes, Diviya Sinha, Kerry S Russell, Mark Collinge, William C Sessa, David Fulton, Manuel Morales-ruiz, Jeffrey R BenderAbstract:Abstract —17β-Estradiol (E2) is a rapid activator of endothelial nitric oxide synthase (eNOS). The product of this activation event, NO, is a fundamental determinant of cardiovascular homeostasis. We previously demonstrated that E2-stimulated endothelial NO release can occur without an increase in cytosolic Ca2+. Here we demonstrate for the first time, to our knowledge, that E2 rapidly induces phosphorylation and activation of eNOS through the phosphatidylinositol 3 (PI3)-kinase–Akt pathway. E2 treatment (10 ng/mL) of the human endothelial cell line, EA.hy926, resulted in increased NO production, which was abrogated by the PI3-kinase inhibitor, LY294002, and the Estrogen receptor antagonist ICI 182,780. E2 stimulated rapid Akt phosphorylation on serine 473. As has been shown for vascular endothelial growth factor, eNOS is an E2-activated Akt substrate, demonstrated by rapid eNOS phosphorylation on serine 1177, a critical residue for eNOS activation and enhanced sensitivity to resting cellular Ca2+ levels. Adenoviral-mediated EA.hy926 transduction confirmed functional involvement of Akt, because a kinase-deficient, dominant-negative Akt abolished E2-stimulated NO release. The Membrane-impermeant E2BSA conjugate, shown to bind endothelial cell Membrane sites, also induced rapid Akt and consequent eNOS phosphorylation. Thus, engagement of Membrane Estrogen receptors results in rapid endothelial NO release through a PI3-kinase–Akt-dependent pathway. This explains, in part, the reduced requirement for cytosolic Ca2+ fluxes and describes an important pathway relevant to cardiovascular pathophysiology.