Project description:Lung cancer remains the leading cause of cancer-related deaths worldwide. M-NM-2-arrestin-1 (ARRB1), a scaffolding protein involved in the termination or desensitization of signals arising from activated G-protein-coupled receptors (GPCRs) has been shown to play a role in invasion and proliferation of many cancers, including nicotine-induced proliferation of human nonM-bM-^@M-^Ssmall cell lung cancers (NSCLCs). In this study, we analyzed nicotine induced and M-NM-2-arrestin-1 dependent genes from the microarray data. Our analysis show that SCF (Stem cell factor) strongly differentiated smokers from non-smokers implying an important role of this gene in NSCLCs. SCF, a major cytokine is the ligand for the c-Kit proto-oncogene. Here we elucidate the molecular mechanisms by which nicotine as well as EGF induces the expression of SCF in lung adenocarcinoma cell lines A549 and H1650. ChIP assays and transient transfection experiments showed that transcription factor E2F1 can positively regulate SCF expression at the transcriptional level; depletion of E2F1 or M-NM-2-arrestin-1 prevented the nicotine-mediated induction of SCF. Given that the binding of SCF to c-Kit leads to activation of multiple downstream signaling pathways including Src, PI3K, MEK and EGFR pathways, our data suggest that the SCF plays a central role in lung carcinogenesis, and may be a potential therapeutic target for combating NSCLC. Studies presented here also provide evidence that SCF along with nicotine promotes self-renewal and proliferation of lung cancer stem cells (CSCs). Our findings reveal an important role and prognostic significance of SCF that can serve as a novel prognostic and predictive biomarker for NSCLC. Transfection of A549 cell line with control siRNA, Beta arrestin siRNA and then stimulation of nicotine
Project description:Lung cancer remains the leading cause of cancer-related deaths worldwide. β-arrestin-1 (ARRB1), a scaffolding protein involved in the termination or desensitization of signals arising from activated G-protein-coupled receptors (GPCRs) has been shown to play a role in invasion and proliferation of many cancers, including nicotine-induced proliferation of human non–small cell lung cancers (NSCLCs). In this study, we analyzed nicotine induced and β-arrestin-1 dependent genes from the microarray data. Our analysis show that SCF (Stem cell factor) strongly differentiated smokers from non-smokers implying an important role of this gene in NSCLCs. SCF, a major cytokine is the ligand for the c-Kit proto-oncogene. Here we elucidate the molecular mechanisms by which nicotine as well as EGF induces the expression of SCF in lung adenocarcinoma cell lines A549 and H1650. ChIP assays and transient transfection experiments showed that transcription factor E2F1 can positively regulate SCF expression at the transcriptional level; depletion of E2F1 or β-arrestin-1 prevented the nicotine-mediated induction of SCF. Given that the binding of SCF to c-Kit leads to activation of multiple downstream signaling pathways including Src, PI3K, MEK and EGFR pathways, our data suggest that the SCF plays a central role in lung carcinogenesis, and may be a potential therapeutic target for combating NSCLC. Studies presented here also provide evidence that SCF along with nicotine promotes self-renewal and proliferation of lung cancer stem cells (CSCs). Our findings reveal an important role and prognostic significance of SCF that can serve as a novel prognostic and predictive biomarker for NSCLC.
Project description:The multifunctional scaffolding protein M-NM-2-arrestin-1 plays a vital role in mediating the proliferative effects of nicotine through nAChR signaling. M-NM-2-arrestins were initially known as negative regulators of GPCR mediated signaling as they promote internalization and desensitization of GPCRs. However, new roles of M-NM-2-arrestins in receptor trafficking and signaling have been discovered in recent years. They are known to regulate signaling through a number of receptors such as Notch, endothelin A receptor, frizzled, smoothened and the nicotinic cholinergic receptors. Studies from our lab revealed that nAChR signaling induces the translocation of M-NM-2-arrestin-1 to the nucleus, in a Src dependent manner, where it directly binds to the proliferative E2Fs. Furthermore, the nuclear translocation of M-NM-2-arrestin-1 results in recruitment of p300 to E2F1 regulated proliferative promoters facilitating histone acetylation and transcription of these promoters. Given the role of M-NM-2-arrestin-1 in nicotine induced gene expression, we attempted to explore the global association of M-NM-2-arrestin-1 to the genomic regions upon nicotine stimulation by ChIP sequencing. It was found that M-NM-2-arrestin-1 is recruited on the promoters of many genes that regulate EMT as well as other regulatory pathways. In this assay, M-NM-2-arrestin-1 was found to be associated with the promoter regions of genes such as ZNF768, ZNF131, CSF3R, HMGA2, TAL1, RCC1, NKX2-4 etc in response to nicotine stimulation. Serum starved/quiescent A549 cells and Nicotine stimulated A549 cells
Project description:The multifunctional scaffolding protein β-arrestin-1 plays a vital role in mediating the proliferative effects of nicotine through nAChR signaling. β-arrestins were initially known as negative regulators of GPCR mediated signaling as they promote internalization and desensitization of GPCRs. However, new roles of β-arrestins in receptor trafficking and signaling have been discovered in recent years. They are known to regulate signaling through a number of receptors such as Notch, endothelin A receptor, frizzled, smoothened and the nicotinic cholinergic receptors. Studies from our lab revealed that nAChR signaling induces the translocation of β-arrestin-1 to the nucleus, in a Src dependent manner, where it directly binds to the proliferative E2Fs. Furthermore, the nuclear translocation of β-arrestin-1 results in recruitment of p300 to E2F1 regulated proliferative promoters facilitating histone acetylation and transcription of these promoters. Given the role of β-arrestin-1 in nicotine induced gene expression, we attempted to explore the global association of β-arrestin-1 to the genomic regions upon nicotine stimulation by ChIP sequencing. It was found that β-arrestin-1 is recruited on the promoters of many genes that regulate EMT as well as other regulatory pathways. In this assay, β-arrestin-1 was found to be associated with the promoter regions of genes such as ZNF768, ZNF131, CSF3R, HMGA2, TAL1, RCC1, NKX2-4 etc in response to nicotine stimulation.
Project description:Description Drosophila melanogaster nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that present a target for insecticides. However, a better understanding of in vioreceptor subunit composition is needed for effective design of insecticides. Alpha-neurotxins are known as peptide toxins capable to block nAChRs by binding to its target subunits. To facilitate the analysis of nAChRs we used a CRISPR/Cas9 strategy to generate null alleles for all ten nAChR subunit genes. We studied interactions of nAChRs to a snake toxin by using styrene maleic acid lipid particles (SMALPs) extraction method. For the null alleles which are impaired in locomotor activities we examined the binding of nAChRs incorporated into SMALPs to alpha bungarotoxin by employing mass spectrometry. We show native ligand interactions to Dalpha5, Dalpha6 and Dalpha7 subunits and reveal glycosylation sites of Dalpha5 and Dalpha7 by a glycoproteomic approach. Finally, we report the localization of fluorescent tagged Dalpha6 across nervous system development
Project description:Myocardial aging leads to a reduction of beta-adrenergic receptor-induced metabolic and contractile responsiveness. We hypothesize that a change in the patterns of gene expression is important in these age-related events. To test this, hearts were harvested from young and aged male rats (3-4 and 20-22 mo, respectively). Total mRNA was extracted and prepared for hybridization to Affymetrix U34A GeneChips. Filtering criteria, involving fold change and a statistical significance cutoff were employed, yielding 263 probe pairs exhibiting differential signals. Of the 163 annotated genes, at least 56 (34%) were classified as signaling/cell communication. Of these 56, approximately half were directly involved in G protein-coupled receptor signaling pathways. We next determined which of these changes might be involved in anti-adrenergic activity and identified 19 potentially important gene products. Importantly, we observed a decrease in beta1-adrenergic receptor and adenylyl cyclase mRNAs, whereas the mRNA encoding beta-arrestin increased. Furthermore, the results demonstrate an increase in mRNAs encoding the adenosine A1 receptor and phospholipase D, which could increase anti-adrenergic effects. Moreover, the mRNAs encoding the muscarinic M3 receptor, nicotinic acetylcholine receptor beta3, and nicotinic acetylcholine receptor-related protein were increased as was the mRNA encoding guanylate kinase-associated protein. Interestingly, we also observed eight mRNAs whose abundance changed three- to sixfold with aging that could be considered as being compensatory. Although these results do not prove causality, they demonstrate that cardiac aging is associated with changes in the profiles of gene expression and that many of these changes may contribute to reduced adrenergic signaling.
Project description:Studies using mice with beta4 nicotinic acetylcholine receptor (nAChR) subunit deficiency (beta4-/- mice) helped reveal the roles of this subunit in bradycardiac response to vagal stimulation, nicotine-induced seizure activity and anxiety. In order to identify genes that might be related to beta4-containing nAChRs activity, we compared the mRNA expression profiles of brains from beta4-/- and wild-type mice using Affymetrix U74Avr2 microarray. Keywords: knockout mice, nicotinic acetylcholine receptor
Project description:Nicotine and nicotinic acetylcholine receptors (nAChRs) are considred to be involved in the progression of lung carcinomas. α5-nAChR is believed to be associated with lung cancer risk and onset, however its function and physiologic roles is far from clear. We use microarry to detail the global programme of gene expression underlying knockdown CHRNA5, encoding α5-nAChR, in human lung cancer A549 cells compared with control.
Project description:Edelstein1996 - EPSP ACh species
Model of a nicotinic Excitatory Post-Synaptic Potential in a Torpedo electric organ. Acetylcholine is represented explicitely as a molecular species.
This model has initially been encoded using StochSim.
This model is described in the article:
A kinetic mechanism for nicotinic acetylcholine receptors based on multiple allosteric transitions.
Edelstein SJ, Schaad O, Henry E, Bertrand D, Changeux JP.
Biol. Cybern. 1996 Nov; 75(5):361-79
Abstract:
Nicotinic acetylcholine receptors are transmembrane oligomeric proteins that mediate interconversions between open and closed channel states under the control of neurotransmitters. Fast in vitro chemical kinetics and in vivo electrophysiological recordings are consistent with the following multi-step scheme. Upon binding of agonists, receptor molecules in the closed but activatable resting state (the Basal state, B) undergo rapid transitions to states of higher affinities with either open channels (the Active state, A) or closed channels (the initial Inactivatable and fully Desensitized states, I and D). In order to represent the functional properties of such receptors, we have developed a kinetic model that links conformational interconversion rates to agonist binding and extends the general principles of the Monod-Wyman-Changeux model of allosteric transitions. The crucial assumption is that the linkage is controlled by the position of the interconversion transition states on a hypothetical linear reaction coordinate. Application of the model to the peripheral nicotine acetylcholine receptor (nAChR) accounts for the main properties of ligand-gating, including single-channel events, and several new relationships are predicted. Kinetic simulations reveal errors inherent in using the dose-response analysis, but justify its application under defined conditions. The model predicts that (in order to overcome the intrinsic stability of the B state and to produce the appropriate cooperativity) channel activation is driven by an A state with a Kd in the 50 nM range, hence some 140-fold stronger than the apparent affinity of the open state deduced previously. According to the model, recovery from the desensitized states may occur via rapid transit through the A state with minimal channel opening, thus without necessarily undergoing a distinct recovery pathway, as assumed in the standard 'cycle' model. Transitions to the desensitized states by low concentration 'pre-pulses' are predicted to occur without significant
channel opening, but equilibrium values of IC50 can be obtained only with long pre-pulse times. Predictions are also made concerning allosteric effectors and their possible role in coincidence detection. In terms of future developments, the analysis presented here provides a physical basis for constructing more biologically realistic models of synaptic modulation that may be applied to artificial neural networks.
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Project description:This manuscript is a companion paper to Ulleryd M.U. et al (1). Data shown here include RNA sequencing data from whole aorta of ApoE-/- mice treated with the alpha 7 nicotinic acetylcholine receptor (α7nAChR) agonist AZ6983 for 8 weeks using subcutaneously implanted osmotic minipumps. 1. Ulleryd MA, Mjornstedt F, Panagaki D, Yang LJ, Engevall K, Gutierrez S, et al. Stimulation of alpha 7 nicotinic acetylcholine receptor (α7nAChR) inhibits atherosclerosis via immunomodulatory effects on myeloid cells Re-submitted. 2019.