scholarly journals NanoLuc (NLuc) complementation assay elucidates role of specific G‐proteins in GPR88 signaling

2021 ◽  
Vol 35 (S1) ◽  
Author(s):  
Kristie Ruddick ◽  
Abedalrahman Elayan ◽  
Hannah Nelson ◽  
Céline Laschet ◽  
Julien Hanson ◽  
...  
Keyword(s):  
G Proteins ◽  
Complementation Assay

scholarly journals Critical Role of Pertussis Toxin Sensitive G Proteins in the Activation of TRPC4 and TRPC5 Channels

2010 ◽  
Vol 98 (3) ◽  
pp. 326a-327a
Author(s):  
Rui Xiao ◽  
Jinbin Tian ◽  
Jisen Tang ◽  
Alexander V. Zholos ◽  
Michael X. Zhu
Keyword(s):  
G Proteins ◽  
Pertussis Toxin ◽  
Critical Role ◽  
Trpc5 Channels

scholarly journals Mutations in the ‘DRY’ motif of the CB1 cannabinoid receptor result in biased receptor variants

2014 ◽  
Vol 54 (1) ◽  
pp. 75-89 ◽  
Author(s):  
Pál Gyombolai ◽  
András D Tóth ◽  
Dániel Tímár ◽  
Gábor Turu ◽  
László Hunyady
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Double Mutant ◽  
Cannabinoid Receptor ◽  
Camp Accumulation ◽  
Protein Activation ◽  
Cb1 Cannabinoid Receptor ◽  
G Protein Activation ◽  
Dry Motif

The role of the highly conserved ‘DRY’ motif in the signaling of the CB1cannabinoid receptor (CB1R) was investigated by inducing single-, double-, and triple-alanine mutations into this site of the receptor. We found that the CB1R-R3.50A mutant displays a partial decrease in its ability to activate heterotrimeric Goproteins (∼80% of WT CB1R (CB1R-WT)). Moreover, this mutant showed an enhanced basal β-arrestin2 (β-arr2) recruitment. More strikingly, the double-mutant CB1R-D3.49A/R3.50A was biased toward β-arrs, as it gained a robustly increased β-arr1 and β-arr2 recruitment ability compared with the WT receptor, while its G-protein activation was decreased. In contrast, the double-mutant CB1R-R3.50A/Y3.51A proved to be G-protein-biased, as it was practically unable to recruit β-arrs in response to agonist stimulus, while still activating G-proteins, although at a reduced level (∼70% of CB1R-WT). Agonist-induced ERK1/2 activation of the CB1R mutants showed a good correlation with their β-arr recruitment ability but not with their G-protein activation or inhibition of cAMP accumulation. Our results suggest that G-protein activation and β-arr binding of the CB1R are mediated by distinct receptor conformations, and the conserved ‘DRY’ motif plays different roles in the stabilization of these conformations, thus mediating both G-protein- and β-arr-mediated functions of CB1R.

Biosynthesis of paf-acether in cultured-mouse mast cells: The role of calcium and G proteins

1992 ◽  
Vol 184 (3) ◽  
pp. 1425-1431 ◽  
Author(s):  
Francine Joly ◽  
Francis Beauvais ◽  
Ewa Ninio
Keyword(s):  
Mast Cells ◽  
G Proteins

scholarly journals Heterotrimeric G-Proteins Are Indispensable for FLT3-ITD autophosphorylation and Oncogenic Function

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2712-2712
Author(s):  
Maike Rehage ◽  
Susanne Wingert ◽  
Nadine Haetscher ◽  
Sabrina Bothur ◽  
Hubert Serve ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
G Protein ◽  
G Proteins ◽  
B Cell Lymphoma ◽  
Physical Interaction ◽  
Heterotrimeric G Proteins ◽  
Leukemic Transformation ◽  
Hematopoietic Stem ◽  
Oncogenic Function

Abstract Heterotrimeric G-proteins transmit signals of G-protein coupled receptors and regulate many basic cellular functions. However, their role in normal and malignant hematopoietic stem cells remains obscure. Activating mutations in the heterotrimeric G-protein Gaq were found in various cancers and its expression is enhanced in diffuse large B-cell lymphoma and T-ALL. Our previous data suggested the involvement of heterotrimeric G-proteins in Flt3-ITD-mediated leukemic transformation. FMS-like tyrosine kinase 3 with internal tandem duplication (FLT3-ITD) is a frequent oncoprotein in acute myeloid leukemia causing constitutive active STAT5 signaling. Here, we investigated a novel role of Gaq in Flt3-ITD-induced leukemic transformation. We could show that Gaq is indispensable for aberrant FLT3-ITD activation and oncogenic function as Gaq activity is necessary to maintain the autophosphorylation of FLT3-ITD. Gaq abrogation resulted in diminished cell proliferation and colony formation as well as delayed leukemogenesis in vivo of Flt3-ITD leukemic cells. Importantly, the growth inhibition could be rescued by addition of IL3 and did not occur in the presence of FLT3 ligand-activated FLT3 wildtype receptor, demonstrating the specificity of Gaq requirement for FLT3-ITD oncogenic signaling. Interestingly, co-immunoprecipitations revealed a direct physical interaction between FLT3-ITD and Gaq which did not require phosphorylation of the receptor tyrosine kinase. Hence, FLT3-ITD hyperphosphorylation seems to be rather a consequence of the interaction than a prerequisite. Flt3-ITD-induced transformation of murine hematopoietic stem/progenitor cells (HSPCs) strictly depended on the presence of Gaq, and the ablation of Gaq/11 in transplanted Flt3-ITD-transduced HSPCs from conditional Gaq/11 double knock-out mice delayed leukemic burden. These findings of an unexpected, yet critical, role of Gaq place the molecule as an important target for antileukemic strategies. Disclosures No relevant conflicts of interest to declare.

scholarly journals A2B Adenosine Receptor and Cancer

2019 ◽  
Vol 20 (20) ◽  
pp. 5139 ◽  
Author(s):  
Zhan-Guo Gao ◽  
Kenneth A. Jacobson
Keyword(s):  
G Proteins ◽  
Anticancer Agents ◽  
Immune Suppression ◽  
Adenosine Receptors ◽  
Immune Surveillance ◽  
G Protein Coupled Receptors ◽  
Normal Tissues ◽  
Cancer Tissues ◽  
G Protein Coupled

There are four subtypes of adenosine receptors (ARs), named A1, A2A, A2B and A3, all of which are G protein-coupled receptors (GPCRs). Locally produced adenosine is a suppressant in anti-tumor immune surveillance. The A2BAR, coupled to both Gαs and Gαi G proteins, is one of the several GPCRs that are expressed in a significantly higher level in certain cancer tissues, in comparison to adjacent normal tissues. There is growing evidence that the A2BAR plays an important role in tumor cell proliferation, angiogenesis, metastasis, and immune suppression. Thus, A2BAR antagonists are novel, potentially attractive anticancer agents. Several antagonists targeting A2BAR are currently in clinical trials for various types of cancers. In this review, we first describe the signaling, agonists, and antagonists of the A2BAR. We further discuss the role of the A2BAR in the progression of various cancers, and the rationale of using A2BAR antagonists in cancer therapy.

Modification of cardiac β-adrenoceptor mechanisms by H2O2

1998 ◽  
Vol 274 (2) ◽  
pp. H416-H423 ◽  
Author(s):  
Sujata Persad ◽  
Heinz Rupp ◽  
Rashi Jindal ◽  
Jugpal Arneja ◽  
Naranjan S. Dhalla
Keyword(s):  
Oxidative Stress ◽  
Signal Transduction ◽  
Adenylyl Cyclase ◽  
G Proteins ◽  
Cardiac Dysfunction ◽  
Biochemical Parameters ◽  
Adenylyl Cyclase Activity ◽  
High Concentrations ◽  
Stimulation Of

From the role of oxidative stress in cardiac dysfunction, we investigated the effect of H2O2, an activated species of oxygen, on β-adrenoceptors, G proteins, and adenylyl cyclase activities. Rat heart membranes were incubated with different concentrations of H2O2before the biochemical parameters were measured. Both the affinity and density of β1-adrenoceptors were decreased, whereas the density of the β2-adrenoceptors was decreased and the affinity was increased by 1 mM H2O2. Time- and concentration-dependent biphasic changes in adenylyl cyclase activities in the absence or presence of isoproterenol were observed when membranes were incubated with H2O2; however, activation of the enzyme by isoproterenol was increased or unaltered. The adenylyl cyclase activities in the absence or presence of forskolin, NaF, and Gpp(NH)p were depressed by H2O2. Catalase alone or in combination with mannitol was able to significantly decrease the magnitude of alterations due to H2O2. The cholera toxin-stimulated adenylyl cyclase activity and ADP ribose labeling of Gs proteins were decreased by treatment with 1 mM H2O2, whereas Gi protein activities, as reflected by pertussis toxin-stimulation of adenylyl cyclase and ADP ribosylation, were unaltered. The Gs and Gi protein immunoreactivities, estimated by labeling with respective antibodies, indicate a decrease in binding to the 45-kDa band of Gs protein, whereas no change in the binding of antibodies to the 52-kDa band of Gs protein or the 40-kDa subunit of Gi protein was evident when the membranes were treated with 1 mM H2O2. These results suggest that H2O2in high concentrations may attenuate the β-adrenoceptor-linked signal transduction in the heart by changing the functions of Gs proteins and the catalytic subunit of the adenylyl cyclase enzyme.

G proteins activate ionic conductances at multiple sites in T84 cells

1997 ◽  
Vol 272 (4) ◽  
pp. C1222-C1231
Author(s):  
L. Izu ◽  
M. Li ◽  
R. DeMuro ◽  
M. E. Duffey
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Cell Voltage ◽  
Equilibrium Potential ◽  
T84 Cells ◽  
Ionic Conductances ◽  
Inward Currents ◽  
Cl Channels ◽  
K Current

We examined the role of G proteins in activation of ionic conductances in isolated T84 cells during cholinergic stimulation. When cells were whole cell voltage clamped to the K+ equilibrium potential (E(K)) or Cl- equilibrium potential (E(Cl)) under standard conditions, the cholinergic agonist, carbachol, induced a large oscillating K+ current but only a small inward current. Addition of the GDP analogue, guanosine 5'-O-(2-thiodiphosphate), to pipettes blocked the ability of carbachol to activate the K+ current. Addition of the nonhydrolyzable GTP analogue, guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS), to pipettes stimulated large oscillating K+ and inward currents. This occurred even when Ca2+ was absent from the bath but not when the Ca2+ chelator, ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, was added to pipettes. When all pipette and bath K+ was replaced with Na+ and cells were voltage clamped between E(Na) and E(Cl), GTPgammaS activated oscillating Na+ and Cl- currents. Finally, addition of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] to pipettes activated large oscillating K+ currents but only small inward currents. These results suggest that a carbachol-induced release of Ca2+ from intracellular stores is activated by a G protein through the phospholipase C-Ins(1,4,5)P3 signaling pathway. In addition, this or another G protein activates Cl- current by directly gating Cl- channels to increase their sensitivity to Ca2+.

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