G protein‐coupled receptors and signaling pathways regulating growth responses
            <sup>1</sup>

Post, Ginell R.; Brown, Joan Heller

doi:10.1096/fasebj.10.7.8635691

Cited by 206 publications

(171 citation statements)

References 13 publications

Supporting

Mentioning

166

Contrasting

Order By: Relevance

“…Treatment with PTX for 24 h prior to the addition of thrombin did not inhibit rounding (Table I). This is consistent with our observation that the thrombin receptor does not interact with G i to inhibit cyclic AMP formation in 1321N1 cells (18,48) and with our finding that thrombin-induced mitogenesis and AP-1-mediated gene expression are both PTX-insensitive (10,18). Ca 2ϩ Requirement for Thrombin-induced Rounding-The thrombin receptor in fibroblasts and 1321N1 cells couples via a G q -dependent pathway to stimulate phosphoinositide hydrolysis and mobilize intracellular Ca 2ϩ (16,18,49).…”

Section: Figsupporting

confidence: 93%

Requirement for Rho-mediated Myosin Light Chain Phosphorylation in Thrombin-stimulated Cell Rounding and Its Dissociation from Mitogenesis

Majumdar

Seasholtz

Goldstein

et al. 1998

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Thrombin treatment causes a dose-dependent rounding of 1321N1 astrocytoma cells. This cytoskeletal response is rapid, peaking 2 h after thrombin stimulation, and reverses by 50% after 24 h. The thrombin receptor peptide SFLLRNP also induces cell rounding, whereas other G protein-linked receptor agonists such as carbachol, lysophosphatidic acid, or bradykinin fail to do so. Results of studies using pharmacological inhibitors do not support a requirement for phosphatidylinositol 3-kinase, mitogen-activated protein kinase, or Ca 2؉ mobilization in this response. Inhibition of protein kinase C or tyrosine kinase produces minimal blockade. Pertussis toxin treatment is also without effect. However, thrombin-induced rounding is fully blocked by the C3 toxin from Clostridium botulinum, which specifically ADP-ribosylates and inactivates the small G protein Rho. Thrombin also leads to a rapid, 2.4-fold increase in 32 P incorporation into myosin light chain while carbachol does not. Myosin phosphorylation, like cell rounding is inhibited by inactivation of Rho with C3 exoenzyme, suggesting that myosin phosphorylation is necessary for this cytoskeletal response. This is supported by the observation that thrombin-induced rounding is also blocked by the myosin light chain kinase inhibitor KT5926. However, treatment with KT5926 fails to inhibit mitogenesis. Thus, cell rounding is not prerequisite to thrombin-induced DNA synthesis. We conclude that stimulation of the heterotrimeric G protein-coupled thrombin receptor in 1321N1 cells activates Rhodependent pathways for both DNA synthesis and cell rounding, the cytoskeletal response being mediated in part through increases in myosin phosphorylation.Thrombin is a protease known to act through a specific seven-transmembrane spanning G protein-coupled receptor. Thrombin activates its receptor through a proteolytic cleavage mechanism which unmasks a new amino terminus that functions as a tethered ligand to activate receptor signaling (1-4). A synthetic peptide analogous to the first five or six NH 2 -terminal amino acids of the receptor elicits responses similar to thrombin in many cell types (4 -8). The best characterized physiological responses to thrombin are its effects on platelet function and DNA synthesis (8 -12). Thrombin can also elicit cytoskeletal responses, and has been shown to induce cell rounding in neurons and astrocytes (5,13,14). Previous work investigating the mechanism by which thrombin changes cell morphology has shown the process to be activated by the thrombin receptor peptide and thus to be mediated through a cell surface thrombin receptor rather than by other non-receptor-mediated proteolytic mechanisms (5, 14, 15).In 1321N1 astrocytoma cells, thrombin receptor activation stimulates phospholipase C through G q , increasing intracellular Ca 2ϩ , and activating protein kinase C (PKC) 1 (10, 16 -18). The muscarinic receptor in 1321N1 cells is also coupled to activation of phospholipase C through Gq, and carbachol elicits changes in phospholipid metabolism, Ca 2ϩ...

show abstract

Section: Figsupporting

confidence: 93%

Requirement for Rho-mediated Myosin Light Chain Phosphorylation in Thrombin-stimulated Cell Rounding and Its Dissociation from Mitogenesis

Majumdar

Seasholtz

Goldstein

et al. 1998

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…There are several examples of cross-talk between Ras-related protein and heterotrimeric G-protein signaling pathways (25,28). However, in every instance identified so far, activated heterotrimeric G-protein subunits either activate small G-proteins or work in concert with activated small G-proteins to were transfected into COS-7 cells along with pFR-Luc, pSV-␤gal, and either pFA2-cJun (cJun), pFA2-CHOP (CHOP), pFA2-CREB (CREB), or pFA2-Elk1 (Elk1) and relative luciferase activities determined.…”

Section: Resultsmentioning

confidence: 99%

Activation of Heterotrimeric G-protein Signaling by a Ras-related Protein

Cismowski¹,

Ma²,

Ribas³

et al. 2000

Journal of Biological Chemistry

151

157

View full text Add to dashboard Cite

Utilizing a functional screen in the yeast Saccharomyces cerevisiae we identified mammalian proteins that activate heterotrimeric G-protein signaling pathways in a receptor-independent fashion. One of the identified activators, termed AGS1 (for activator of G-protein signaling), is a human Ras-related G-protein that defines a distinct subgroup of the Ras superfamily. Expression of AGS1 in yeast and in mammalian cells results in specific activation of G␣ i /G␣ o heterotrimeric signaling pathways. In addition, the in vivo and in vitro properties of AGS1 are consistent with it functioning as a direct guanine nucleotide exchange factor for G␣ i /G␣ o . AGS1 thus presents a unique mechanism for signal integration via heterotrimeric G-protein signaling pathways. GPCR1 signaling pathways represent one of the most widely used mechanisms in nature for transducing signals from the extracellular to the intracellular environment. Each step in the activated GPCR signaling cascade presents a potential regulatory checkpoint for fine-tuning and directing the signal. Although a number of regulatory molecules affecting GPCR signaling have been identified (1)(2)(3)(4)(5)(6)(7)(8), evidence suggests the presence of additional pathway modulators (8 -10). To isolate such modulators, we developed a series of functional screens in the yeast Saccharomyces cerevisiae designed to detect mammalian proteins that either activate or inactivate the pheromone response pathway, a G-protein coupled pathway in which G␤␥ acts as the positive signal transducer (11,12). Genetic manipulation of the yeast strains allowed detection of mammalian modulators through simple growth screens, and the functional redundancy between the pheromone response pathway and mammalian GPCR pathways (13-16) allowed us to replace the yeast G␣ with human G␣ i2 , thereby biasing the screens toward the non-yeast component of the pathway. From these screens we identified three mammalian proteins that appeared to activate signaling by distinct mechanisms (11,12). As expression of these proteins did not alter G-protein expression levels in yeast, we termed these proteins AGS for activators of G-protein signaling. This report describes the functional characterization of AGS1, a Ras-related protein isolated from a screen of human liver cDNA. EXPERIMENTAL PROCEDURESStrains and Plasmids-Plasmid constructions, except as indicated below, have been described previously (11). Plasmid pSV-␤gal was purchased from Promega; pYES2, pCEP4, pcDNA3.1(ϩ), pcDNA3.1-His-lacZ, and pcDNA3.1-HisC were from Invitrogen; pYEX4T1 was from Amrad Biotech and pFA2-cJun, pFA2-Elk1, pFA2-CREB, pFA-CHOP, pFR-Luc, pFC-MEK1, and pBluescriptSK(ϩ) were from Stratagene. A plasmid carrying human transducin-␣ (GNAZ) cDNA sequences in pBluescriptSK(ϩ) was a gift from M. Simon. AGS1 and AGS1-G31V (11) were amplified from pYES2 plasmids and ligated into pcDNA3.1-HisC and pYEX4T1, placing the AGS1 coding sequences in-frame with, respectively, an N-terminal His 6 tag sequence and an N-terminal GST sequence. In a similar f...

show abstract

“…GPCRs have been related to a variety of cellular functions, including cell proliferation, differentiation, survival, and migration. 39,40 To study the role of the peripheral cannabinoid receptor when overexpressed on myeloid cells, we investigated the effects of cannabinoid ligands on the myeloid cell line NFS 78 and on 32D/G-CSF-R cells transfected with the Cb2 exon-1B/exon-2 splice variant. We demonstrate that stimulation of Cb2-overexpressing cells by its potent agonist 2-AG induces migration in vitro at nanomolar concentrations.…”

Section: Discussionmentioning

confidence: 99%

Hematopoietic cells expressing the peripheral cannabinoid receptor migrate in response to the endocannabinoid 2-arachidonoylglycerol

Jordà

Verbakel

Valk

et al. 2002

Blood

148

View full text Add to dashboard Cite

Cb2 is a novel protooncogene encoding the peripheral cannabinoid receptor. Previous studies demonstrated that 2 distinct noncoding first exons exist: exon-1A and exon-1B, which both splice to proteincoding exon-2. We demonstrate that in retrovirally induced murine myeloid leukemia cells with proviral insertion in Cb2, exon-1B/exon-2 Cb2 messenger RNA levels have been increased, resulting in high receptor numbers. In myeloid leukemia cells without virus insertion in this locus, low levels of only exon-1A/exon-2 Cb2 transcripts were present and receptors could not be detected. To elucidate the function of Cb2 in myeloid leukemia cells, a set of in vitro experiments was carried out using 32D/G-CSF-R (granulocyte colony-stimulating factor receptor) cells transfected with exon-1B/exon-2 Cb2 complementary DNA and a myeloid cell line carrying a virus insertion in Cb2 (ie, NFS 78). We demonstrate that a major function of the Cb2 receptor is stimulation of migration as determined in a transwell assay. The cannabinoid receptors belong to the superfamily of 7-transmembrane G protein-coupled receptors (GPCRs). Several GPCRs have been shown to be involved in cell growth and oncogenesis as the result of aberrant expression. [5][6][7] Examples of GPCRs with transforming ability are the ␣1B-adrenergic, 8 thrombin, 9 and serotonin 1c receptors 10 and the receptor encoded by MAS oncogene. 11,12 Our previous observation that Cb2 is a common virus integration site suggests that aberrant expression of this 7-transmembrane receptor may be a critical event in transformation in certain cases of leukemia. 3 The protein-coding region of Cb2 is located on a single exon (exon-2) of approximately 4 kilobases. Recently we identified 2 distinct 5Ј noncoding exons (ie, exon-1A and exon-1B) previously designated exon-1 and exon-1Ј, respectively. 3 In the study presented here we first carried out experiments to investigate Cb2 messenger RNA (mRNA) transcripts and protein expression in leukemic cells with or without retroviral insertion in the Cb2 locus. Secondly, we performed studies to determine the function of the peripheral cannabinoid receptor when overexpressed in myeloid cells.GPCRs have been related to many functions, including cell proliferation, maturation, survival, apoptosis, or migration. 6,13,14 In the present study, we investigated the function of the peripheral cannabinoid receptor when overexpressed on myeloid cells (ie, 32D/G-CSF-R [granulocyte colony-stimulating factor receptor]) in which we overexpressed exon-1B/exon-2 Cb2 splice variant and a myeloid leukemia cell line containing a virus insertion in the Cb2 locus, NFS 78. We also wished to determine which of the large panel of Cb2 ligands that have been identified previously is the true agonist of the receptor. We investigated the effects of natural (␦ 8 24 ) cannabinoids. We show that 2-AG is the most potent agonist for the Cb2 receptor and that a major function of 2-AG is stimulation of migration. We further studied whether 2-AG acts as a chemotactic or chemokinetic age...

show abstract

G protein‐coupled receptors and signaling pathways regulating growth responses ¹

Cited by 206 publications

References 13 publications

Requirement for Rho-mediated Myosin Light Chain Phosphorylation in Thrombin-stimulated Cell Rounding and Its Dissociation from Mitogenesis

Requirement for Rho-mediated Myosin Light Chain Phosphorylation in Thrombin-stimulated Cell Rounding and Its Dissociation from Mitogenesis

Activation of Heterotrimeric G-protein Signaling by a Ras-related Protein

Hematopoietic cells expressing the peripheral cannabinoid receptor migrate in response to the endocannabinoid 2-arachidonoylglycerol

Contact Info

Product

Resources

About

G protein‐coupled receptors and signaling pathways regulating growth responses 1

Cited by 206 publications

References 13 publications

Requirement for Rho-mediated Myosin Light Chain Phosphorylation in Thrombin-stimulated Cell Rounding and Its Dissociation from Mitogenesis

Requirement for Rho-mediated Myosin Light Chain Phosphorylation in Thrombin-stimulated Cell Rounding and Its Dissociation from Mitogenesis

Activation of Heterotrimeric G-protein Signaling by a Ras-related Protein

Hematopoietic cells expressing the peripheral cannabinoid receptor migrate in response to the endocannabinoid 2-arachidonoylglycerol

Contact Info

Product

Resources

About

G protein‐coupled receptors and signaling pathways regulating growth responses ¹