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Emmanuelle Motte, Catherine Le Stunff, Claire Briet, Nicolas Dumaz, Caroline Silve
In acrodysostosis without hormone resistance, a disease caused by phosphodiesterase (PDE)-4D mutations, increased PDE activity leads to bone developmental defects but with normal renal responses to PTH. To identify potential mechanisms for these disparate responses, we compared the effect of PDE activity on hormone signaling through the GPCR-Gsα-cAMP-PKA pathway in cells from two lineages, HEK-293 cells stably overexpressing PTH1R (HEKpthr) and human dermal fibroblasts, including studies evaluating cAMP levels using an Epac-based BRET-sensor for cAMP (CAMYEL)...
November 28, 2016: Molecular and Cellular Endocrinology
Holger Rehmann
Epac1 and Epac2 are cyclic nucleotide-binding (CNB) domain containing proteins, which were originally identified as cAMP-regulated guanine nucleotide exchange factors (GEFs) for the small G-protein Rap. Therefore, Epac proteins founded next to protein kinase A (PKA) and cyclic nucleotide-regulated ion channels the third group of cAMP-responsive proteins in higher organisms. Epac proteins are involved in the regulation of several physiological processes. In particular Epac1 mediates the regulation of molecular processes underlying cell adhesion and mobility...
November 30, 2016: Handbook of Experimental Pharmacology
Ling-Yi Xiao, Wai-Ming Kan
Cyclic adenosine monophosphate (cAMP) regulates many vital functions such as metabolism, proliferation, differentiation and death. Depending on cell types and stimulators, cAMP could either promote or attenuate cell death. cAMP signal can be transduced by protein kinase A (PKA) and/or exchange protein directly activated by cAMP (EPAC). In CML cells, cAMP may suppress their proliferation and enhance their differentiation. However, the role of cAMP on DNA damaging agent toxicity and the mechanism involved has not been studied...
November 25, 2016: European Journal of Pharmacology
M Hwang, Y Go, J-H Park, S-K Shin, S E Song, B-C Oh, S-S Im, I Hwang, Y H Jeon, I-K Lee, S Seino, D-K Song
BACKGROUND: The exchange protein directly activated by cAMP (Epac), which is primarily involved in cAMP signaling, has been known to be essential for controlling body energy metabolism. Epac has two isoforms: Epac1 and Epac2. The function of Epac1 on obesity was unveiled using Epac1 knockout (KO) mice. However, the role of Epac2 in obesity remains unclear. METHODS: To evaluate the role of Epac2 in obesity, we used Epac2a KO mice, which is dominantly expressed in neurons and endocrine tissues...
November 21, 2016: International Journal of Obesity: Journal of the International Association for the Study of Obesity
Hui Wang, William G Robichaux, Ziqing Wang, Fang C Mei, Ming Cai, Guangwei Du, Ju Chen, Xiaodong Cheng
Vascular smooth muscle cell (VSMC) activation in response to injury plays an important role in the development of vascular proliferative diseases, including restenosis and atherosclerosis. The aims of this study were to ascertain the physiological functions of exchange proteins directly activated by cAMP isoform 1 (Epac1) in VSMC and to evaluate the potential of Epac1 as therapeutic targets for neointima formation during vascular remodeling. In a mouse carotid artery ligation model, genetic knockdown of the Epac1 gene led to a significant reduction in neointima obstruction in response to vascular injury...
November 10, 2016: Scientific Reports
Jennifer B Stott, Vincenzo Barrese, Iain A Greenwood
OBJECTIVE: To establish the role of Kv7 channels in EPAC (exchange protein directly activated by cAMP)-dependent relaxations of the rat vasculature and to investigate whether this contributes to β-adrenoceptor-mediated vasorelaxations. APPROACH AND RESULTS: Isolated rat renal and mesenteric arteries (RA and MA, respectively) were used for isometric tension recording to study the relaxant effects of a specific EPAC activator and the β-adrenoceptor agonist isoproterenol in the presence of potassium channel inhibitors and cell signaling modulators...
October 27, 2016: Arteriosclerosis, Thrombosis, and Vascular Biology
Anika Sahr, Carmen Wolke, Jonas Maczewsky, Peter Krippeit-Drews, Anja Tetzner, Gisela Drews, Simone Venz, Sarah Gürtler, Jens van den Brandt, Sabine Berg, Paula Döring, Frank Dombrowski, Thomas Walther, Uwe Lendeckel
The angiotensin-converting enzyme 2/angiotensin (Ang)-(1-7)/Mas axis of the renin-angiotensin system often opposes the detrimental effects of the angiotensin-converting enzyme/Ang II/Ang II type 1 receptor axis and has been associated with beneficial effects on glucose homeostasis, whereas underlying mechanisms are mostly unknown. Here we investigate the effects of Ang-(1-7) and its receptor Mas on β-cell function. Isolated islets from Mas-deficient and wild-type mice were stimulated with Ang-(1-7) or its antagonists and effects on insulin secretion determined...
December 2016: Endocrinology
Marisa Coelho, Cátia Soares-Silva, Daniela Brandão, Franca Marino, Marco Cosentino, Laura Ribeiro
PURPOSE: In this review, we aimed to present and discuss the available preclinical and epidemiological evidences regarding the modulation of cancer cell proliferation by β-adrenoceptors (β-AR), with a specific focus on the putative effects of β-blockers according to their pharmacological properties. METHODS: A comprehensive review of the published literature was conducted, and the evidences concerning the involvement of β-AR in cancer as well as the possible role of β-blockers were selected and discussed...
October 5, 2016: Journal of Cancer Research and Clinical Oncology
Angela Yulia, Natasha Singh, Kaiyu Lei, Suren R Sooranna, Mark R Johnson
The factors that initiate human labor are poorly understood. We have tested the hypothesis that a decline in cAMP/PKA function leads to the onset of labor. Initially, we identified myometrial cAMP/PKA responsive genes (6 up-regulated and 5 down-regulated genes) and assessed their expression in myometrial samples taken from different stages of pregnancy and labor. We found that the oxytocin receptor (OTR) was one of the cAMP repressed genes and, given the importance of OTR in the labor process, we studied the mechanisms involved in greater detail using siRNA, chemical agonists and antagonists of the cAMP effectors...
September 27, 2016: Endocrinology
D P Fields, G S Mitchell
Spinal metabotropic serotonin receptors encode transient experiences into long-lasting changes in motor behavior (i.e. motor plasticity). While interactions between serotonin receptor subtypes are known to regulate plasticity, the significance of molecular divergence in downstream G protein coupled receptor signaling is not well understood. Here we tested the hypothesis that distinct cAMP dependent signaling pathways differentially regulate serotonin-induced phrenic motor facilitation (pMF); a well-studied model of spinal motor plasticity...
September 20, 2016: Neuropharmacology
Zhaokang Yang, Hannah Kirton, Moza Al-Owais, Jerôme Thireau, Sylvain Richard, Derek Steele, Chris Peers
AIMS: In the heart, β<sub>1</sub>-adrenergic signaling involves cyclic adenosine monophosphate (cAMP) acting via both protein kinase-A (PKA) and 'exchange protein directly activated by cAMP' (Epac): a guanine nucleotide exchange factor for the small GTPase Rap1. Inhibition of Epac-Rap1 signaling has been proposed as a therapeutic strategy for both cancer and cardiovascular disease. However, previous work suggests that impaired Rap1 signaling may have detrimental effects on cardiac function...
September 21, 2016: Antioxidants & Redox Signaling
George D Bittner, Christopher S Spaeth, Andrew D Poon, Zachary S Burgess, Christopher H McGill
The repair (sealing) of plasmalemmal damage, consisting of small holes to complete transections, is critical for cell survival, especially for neurons that rarely regenerate cell bodies. We first describe and evaluate different measures of cell sealing. Some measures, including morphological/ultra-structural observations, membrane potential, and input resistance, provide very ambiguous assessments of plasmalemmal sealing. In contrast, measures of ionic current flow and dye barriers can, if appropriately used, provide more accurate assessments...
July 2016: Neural Regeneration Research
Evi Glas, Harald Mückter, Thomas Gudermann, Andreas Breit
Gs protein-coupled receptors regulate many vital body functions by activation of cAMP response elements (CRE) via cAMP-dependent kinase A (PKA)-mediated phosphorylation of the CRE binding protein (CREB). Melanocortin 4 receptors (MC4R) are prototypical Gs-coupled receptors that orchestrate the hypothalamic control of food-intake and metabolism. Remarkably, the significance of PKA for MC4R-induced CRE-dependent transcription in hypothalamic cells has not been rigorously interrogated yet. In two hypothalamic cell lines, we observed that blocking PKA activity had only weak or no effects on reporter gene expression...
2016: Scientific Reports
Peter V DiStefano, Alan V Smrcka, Angela J Glading
The phosphoinositide-specific phospholipase C, PLCε, is a unique signaling protein with known roles in regulating cardiac myocyte growth, astrocyte inflammatory signaling, and tumor formation. PLCε is also expressed in endothelial cells, however its role in endothelial regulation is not fully established. We show that endothelial cells of multiple origins, including human pulmonary artery (HPAEC), human umbilical vein (HUVEC), and immortalized brain microvascular (hCMEC/D3) endothelial cells, express PLCε...
2016: PloS One
Walter Miklos, Petra Heffeter, Christine Pirker, Sonja Hager, Christian R Kowol, Sushilla van Schoonhoven, Mirjana Stojanovic, Bernhard K Keppler, Walter Berger
Triapine, an anticancer thiosemicarbazone, is currently under clinical investigation. Whereas promising results were obtained in hematological diseases, trials in solid tumors widely failed. To understand mechanisms causing triapine insensitivity, we have analysed genomic alterations in a triapine-resistant SW480 subline (SW480/tria). Only one distinct genomic loss was observed specifically in SW480/tria cells affecting the phosphodiesterase 4D (PDE4D) gene locus. Accordingly, pharmacological inhibition of PDE4D resulted in significant triapine resistance in SW480 cells...
September 2, 2016: Oncotarget
D Avanzato, T Genova, A Fiorio Pla, M Bernardini, S Bianco, B Bussolati, D Mancardi, E Giraudo, F Maione, P Cassoni, I Castellano, L Munaron
Purinergic signaling is involved in inflammation and cancer. Extracellular ATP accumulates in tumor interstitium, reaching hundreds micromolar concentrations, but its functional role on tumor vasculature and endothelium is unknown. Here we show that high ATP doses (>20 μM) strongly inhibit migration of endothelial cells from human breast carcinoma (BTEC), but not of normal human microvascular EC. Lower doses (1-10 mm result ineffective. The anti-migratory activity is associated with cytoskeleton remodeling and is significantly prevented by hypoxia...
2016: Scientific Reports
Jada C Domingue, Mei Ao, Jayashree Sarathy, Mrinalini C Rao
Bile acids are known to initiate intricate signaling events in a variety of tissues, primarily in the liver and gastrointestinal tract. Of the known bile acids, only the dihydroxy species, deoxycholic acid and chenodeoxycholic acid (CDCA), and their conjugates, activate processes that stimulate epithelial Cl(-) secretion. We have previously published that CDCA acts in a rapid manner to stimulate colonic ion secretion via protein kinase A (PKA)-mediated activation of the dominant Cl(-) channel, the cystic fibrosis transmembrane conductance regulator (CFTR) (AJP 305:C447-56, 2013); however, PKA signaling did not account for the entire CDCA response...
August 24, 2016: American Journal of Physiology. Cell Physiology
Ali M Komai, Saliha Musovic, Eduard Peris, Ahmed Alrifaiy, Mickaël F El Hachmane, Marcus Johansson, Ingrid Wernstedt Asterholm, Charlotta S Olofsson
We investigated the physiological regulation of adiponectin exocytosis in health and metabolic disease by a combination of membrane capacitance patch-clamp recordings and biochemical measurements of short-term (30 min incubations) adiponectin secretion. Adrenaline or the β3 adrenergic receptor agonist CL 316,243 (CL) stimulated adiponectin exocytosis/secretion in cultured 3T3-L1 and in primary subcutaneous mouse adipocytes and the stimulation was inhibited by the Epac (Exchange Protein directly Activated by cAMP) antagonist ESI-09...
August 23, 2016: Diabetes
Takayuki Fujita, Masanari Umemura, Utako Yokoyama, Satoshi Okumura, Yoshihiro Ishikawa
As one of the most important second messengers, 3',5'-cyclic adenosine monophosphate (cAMP) mediates various extracellular signals including hormones and neurotransmitters, and induces appropriate responses in diverse types of cells. Since cAMP was formerly believed to transmit signals through only two direct target molecules, protein kinase A and the cyclic nucleotide-gated channel, the sensational discovery in 1998 of another novel direct effecter of cAMP [exchange proteins directly activated by cAMP (Epac)] attracted a great deal of scientific interest in cAMP signaling...
August 22, 2016: Cellular and Molecular Life Sciences: CMLS
Serge Goupil, Loïze Maréchal, Hassan El Hajj, Marie-Ève Tremblay, François J Richard, Pierre Leclerc
In mammals, adenosine 3', 5'-cyclic monophosphate (cAMP) is known to play highly important roles in sperm motility and acrosomal exocytosis. It is known to act through protein phosphorylation via PRKA and through the activation of guanine nucleotide exchange factors like EPAC. Sperm intracellular cAMP levels depend on the activity of adenylyl cyclases, mostly SACY, though transmembrane-containing adenylyl cyclases are also present, and on the activity of cyclic nucleotide phosphodiesterases (PDE) whose role is to degrade cAMP into 5'-AMP...
2016: PloS One
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