N-ethyl-N-nitrosourea-based generation of mouse models for mutant G protein-coupled receptors

2006 ◽  
Vol 26 (3) ◽  
pp. 209-217 ◽  
Author(s):  
Johannes Grosse ◽  
Patrick Tarnow ◽  
Holger Römpler ◽  
Boris Schneider ◽  
Reinhard Sedlmeier ◽  
...  
Keyword(s):  
G Protein ◽  
Mouse Models ◽  
Germ Line ◽  
Random Mutagenesis ◽  
G Protein Coupled Receptors ◽  
In Vitro Assays ◽  
Vitro Fertilization ◽  
Type 3 ◽  
G Protein Coupled

Chemical random mutagenesis techniques with the germ line supermutagen N-ethyl- N-nitrosourea (ENU) have been established to provide comprehensive collections of mouse models, which were then mined and analyzed in phenotype-driven studies. Here, we applied ENU mutagenesis in a high-throughput fashion for a gene-driven identification of new mutations. Selected members of the large superfamily of G protein-coupled receptors (GPCR), melanocortin type 3 (Mc3r) and type 4 (Mc4r) receptors, and the orphan chemoattractant receptor GPR33, were used as model targets to prove the feasibility of this approach. Parallel archives of DNA and sperm from mice mutagenized with ENU were screened for mutations in these GPCR, and in vitro assays served as a preselection step before in vitro fertilization was performed to generate the appropriate mouse model. For example, mouse models for inherited obesity were established by selecting fully or partially inactivating mutations in Mc4r. Our technology described herein has the potential to provide mouse models for a GPCR dysfunction of choice within <4 mo and can be extended to other gene classes of interest.

scholarly journals Adhesion G Protein–Coupled Receptors: From In Vitro Pharmacology to In Vivo Mechanisms

2015 ◽  
Vol 88 (3) ◽  
pp. 617-623 ◽  
Author(s):  
Kelly R. Monk ◽  
Jörg Hamann ◽  
Tobias Langenhan ◽  
Saskia Nijmeijer ◽  
Torsten Schöneberg ◽  
...  
Keyword(s):  
G Protein ◽  
G Protein Coupled Receptors ◽  
In Vitro Pharmacology ◽  
G Protein Coupled

Selective recruitment of arrestin-3 to clathrin coated pits upon stimulation of G protein-coupled receptors

2000 ◽  
Vol 113 (13) ◽  
pp. 2463-2470 ◽  
Author(s):  
F. Santini ◽  
R.B. Penn ◽  
A.W. Gagnon ◽  
J.L. Benovic ◽  
J.H. Keen
Keyword(s):  
G Protein ◽  
G Protein Coupled Receptors ◽  
Coated Pits ◽  
Over Expression ◽  
Physiological Conditions ◽  
A Cell ◽  
G Protein Coupled ◽  
Comparable Magnitude

Non-visual arrestins (arrestin-2 and arrestin-3) play critical roles in the desensitization and internalization of many G protein-coupled receptors. In vitro experiments have shown that both non-visual arrestins bind with high and approximately comparable affinities to activated, phosphorylated forms of receptors. They also exhibit high affinity binding, again of comparable magnitude, to clathrin. Further, agonist-promoted internalization of many receptors has been found to be stimulated by exogenous over-expression of either arrestin2 or arrestin3. The existence of multiple arrestins raises the question whether stimulated receptors are selective for a specific endogenous arrestin under more physiological conditions. Here we address this question in RBL-2H3 cells, a cell line that expresses comparable levels of endogenous arrestin-2 and arrestin-3. When (beta)(2)-adrenergic receptors are stably expressed in these cells the receptors internalize efficiently following agonist stimulation. However, by immunofluorescence microscopy we determine that only arrestin-3, but not arrestin-2, is rapidly recruited to clathrin coated pits upon receptor stimulation. Similarly, in RBL-2H3 cells that stably express physiological levels of m1AChR, the addition of carbachol selectively induces the localization of arrestin-3, but not arrestin-2, to coated pits. Thus, this work demonstrates coupling of G protein-coupled receptors to a specific non-visual arrestin in an in vivo setting.

scholarly journals Prospects for use of peptides and their derivatives, structurally corresponding to the G protein-coupled receptors, in medicine

2015 ◽  
Vol 61 (1) ◽  
pp. 19-29 ◽  
Author(s):  
A.O. Shpakov ◽  
E.A. Shpakova
Keyword(s):  
G Protein ◽  
Intracellular Signaling ◽  
High Efficiency ◽  
Clinical Medicine ◽  
Inflammatory Diseases ◽  
G Protein Coupled Receptors ◽  
Signaling Cascades ◽  
G Protein Coupled

The regulation of signaling pathways involved in the control of many physiological functions is carried out via the heterotrimeric G protein-coupled receptors (GPCR). The search of effective and selective regulators of GPCR and intracellular signaling cascades coupled with them is one of the important problems of modern fundamental and clinical medicine. Recently data suggest that synthetic peptides and their derivatives, structurally corresponding to the intracellular and transmembrane regions of GPCR, can interact with high efficiency and selectivity with homologous receptors and influence, thus, the functional activity of intracellular signaling cascades and fundamental cellular processes controlled by them. GPCR-peptides are active in both in vitro and in vivo. They regulate hematopoiesis, angiogenesis and cell proliferation, inhibit tumor growth and metastasis, and prevent the inflammatory diseases and septic shock. These data show greatest prospects in the development of the new generations of drugs based on GPCR-derived peptides, capable of regulating the important functions of the organism.

scholarly journals Specific oxylipins enhance vertebrate hematopoiesis via the receptor GPR132

2018 ◽  
Vol 115 (37) ◽  
pp. 9252-9257 ◽  
Author(s):  
Jamie L. Lahvic ◽  
Michelle Ammerman ◽  
Pulin Li ◽  
Megan C. Blair ◽  
Emma R. Stillman ◽  
...  
Keyword(s):  
Fatty Acids ◽  
G Protein ◽  
Cell Lines ◽  
Saturated Fatty Acids ◽  
Receptor Activation ◽  
G Protein Coupled Receptors ◽  
Hydroxy Fatty Acids ◽  
High Affinity ◽  
G Protein Coupled

Epoxyeicosatrienoic acids (EETs) are lipid-derived signaling molecules with cardioprotective and vasodilatory actions. We recently showed that 11,12-EET enhances hematopoietic induction and engraftment in mice and zebrafish. EETs are known to signal via G protein-coupled receptors, with evidence supporting the existence of a specific high-affinity receptor. Identification of a hematopoietic-specific EET receptor would enable genetic interrogation of EET signaling pathways, and perhaps clinical use of this molecule. We developed a bioinformatic approach to identify an EET receptor based on the expression of G protein-coupled receptors in cell lines with differential responses to EETs. We found 10 candidate EET receptors that are expressed in three EET-responsive cell lines, but not expressed in an EET-unresponsive line. Of these, only recombinant GPR132 showed EET-responsiveness in vitro, using a luminescence-based β-arrestin recruitment assay. Knockdown of zebrafish gpr132b prevented EET-induced hematopoiesis, and marrow from GPR132 knockout mice showed decreased long-term engraftment capability. In contrast to high-affinity EET receptors, GPR132 is reported to respond to additional hydroxy-fatty acids in vitro, and we found that these same hydroxy-fatty acids enhance hematopoiesis in the zebrafish. We conducted structure–activity relationship analyses using both cell culture and zebrafish assays on diverse medium-chain fatty acids. Certain oxygenated, unsaturated free fatty acids showed high activation of GPR132, whereas unoxygenated or saturated fatty acids had lower activity. Absence of the carbon-1 position carboxylic acid prevented activity, suggesting that this moiety is required for receptor activation. GPR132 responds to a select panel of oxygenated polyunsaturated fatty acids to enhance both embryonic and adult hematopoiesis.

In-vitro folding and functional characterization of the extracellular domain of G protein-coupled receptors

2002 ◽  
Vol 30 (3) ◽  
pp. A60-A60
Author(s):  
A. Kuntzsch ◽  
U. Grauschopf ◽  
A. Bazarsuren ◽  
K. Wenig ◽  
H. Lilie ◽  
...  
Keyword(s):  
G Protein ◽  
Functional Characterization ◽  
Extracellular Domain ◽  
G Protein Coupled Receptors ◽  
G Protein Coupled

Sphingosine 1-Phosphate (S1P) Induces Migration and ERK/MAP-Kinase-Dependent Proliferation in Chronic Lymphocytic Leukemia (B-CLL) Due to Expression of the G Protein-Coupled Receptors S1P1/4.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4996-4996
Author(s):  
Gabriele Seitz ◽  
Sedat Yildirim ◽  
Andreas M. Boehmler ◽  
Lothar Kanz ◽  
Robert Möhle
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
G Protein ◽  
Cell Lines ◽  
Peripheral Blood ◽  
G Protein Coupled Receptors ◽  
Lymphocytic Leukemia ◽  
S1p Receptors ◽  
Sphingosine 1 Phosphate ◽  
G Protein Coupled

Abstract Egress of lymphocytes from lymphoid organs into the circulation has been shown to depend on the presence of the lipid mediator sphingosine 1-phosphate (S1P) in the peripheral blood, and expression of corresponding S1P receptors (i.e., S1P1), that belong to the family of 7-transmembrane G protein-coupled receptors (GPCR). As circulating lymphocytic lymphoma cells are a hallmark of chronic lymphocytic leukemia, we analyzed expression of different S1P receptors and the effects of S1P on B-CLL cells. By qualitative and quantitative (TaqMan) RT-PCR, significant mRNA expression of S1P1 and S1P4 was found in CLL cell lines (EHEB, MEC-1) and in most samples (S1P1 in 88%, S1P4 in 100%) of primary CD19+ cells isolated from the peripheral blood of untreated B-CLL patients. mRNA of other S1P receptors (S1P2, S1P3, S1P5) was less consistently detected. Normal, nonmalignant B cells were strongly positive for S1P1, while other S1P receptors were weakly expressed or negative. S1P induced typical effects of chemotactic GPCR, such as actin polymerization (analyzed by flow cytometry) and chemotaxis (measured in a modified Boyden chamber assay) in CLL cell lines and primary B-CLL cells. After serum deprivation in vitro, S1P induced phosphorylation of ERK/MAP-kinase as analyzed by Western blot, demonstrating that S1P receptors expressed in CLL were able to activate signaling pathways of GPCR not only related to cell migration and chemotaxis, but also to cell proliferation. Of note, the S1P1 ligand FTY720, which induces receptor internalization after prolonged exposure and acts as an antagonist, resulted in apoptosis in CLL cell lines and primary CLL cells in vitro, as measured by MTT-test and staining with Annexin-FITC, respectively. We conclude that sphingosine 1-phosphate, which is present in the peripheral blood in considerable amounts, contributes to the trafficking of B-CLL cells expressing the GPCRs S1P1/4, and to their prolonged survival.

scholarly journals Mechanisms of cross-talk between G-protein-coupled receptors resulting in enhanced release of intracellular Ca2+

2003 ◽  
Vol 374 (2) ◽  
pp. 281-296 ◽  
Author(s):  
Tim D. WERRY ◽  
Graeme F. WILKINSON ◽  
Gary B. WILLARS
Keyword(s):  
G Protein ◽  
Cross Talk ◽  
Cell Function ◽  
Feedback Regulation ◽  
G Protein Coupled Receptors ◽  
Negative Feedback Regulation ◽  
Cellular Processes ◽  
Heterologous Desensitization ◽  
G Protein Coupled

Alteration in [Ca2+]i (the intracellular concentration of Ca2+) is a key regulator of many cellular processes. To allow precise regulation of [Ca2+]i and a diversity of signalling by this ion, cells possess many mechanisms by which they are able to control [Ca2+]i both globally and at the subcellular level. Among these are many members of the superfamily of GPCRs (G-protein-coupled receptors), which are characterized by the presence of seven transmembrane domains. Typically, those receptors able to activate PLC (phospholipase C) enzymes cause release of Ca2+ from intracellular stores and influence Ca2+ entry across the plasma membrane. It has been well documented that Ca2+ signalling by one type of GPCR can be influenced by stimulation of a different type of GPCR. Indeed, many studies have demonstrated heterologous desensitization between two different PLC-coupled GPCRs. This is not surprising, given our current understanding of negative-feedback regulation and the likely shared components of the signalling pathway. However, there are also many documented examples of interactions between GPCRs, often coupling preferentially to different signalling pathways, which result in a potentiation of Ca2+ signalling. Such interactions have important implications for both the control of cell function and the interpretation of in vitro cell-based assays. However, there is currently no single mechanism that adequately accounts for all examples of this type of cross-talk. Indeed, many studies either have not addressed this issue or have been unable to determine the mechanism(s) involved. This review seeks to explore a range of possible mechanisms to convey their potential diversity and to provide a basis for further experimental investigation.

Phospholipid Scrambling by G Protein–Coupled Receptors

2021 ◽  
Vol 51 (1) ◽  
Author(s):  
George Khelashvili ◽  
Anant K. Menon
Keyword(s):  
G Protein ◽  
Conformational Changes ◽  
Credit Card ◽  
Lipid Membrane ◽  
G Protein Coupled Receptors ◽  
Annual Review ◽  
Publication Date ◽  
Flip Flop ◽  
G Protein Coupled

Rapid flip-flop of phospholipids across the two leaflets of biological membranes is crucial for many aspects of cellular life. The transport proteins that facilitate this process are classified as pump-like flippases and floppases and channel-like scramblases. Unexpectedly, Class A G protein–coupled receptors (GPCRs), a large class of signaling proteins exemplified by the visual receptor rhodopsin and its apoprotein opsin, are constitutively active as scramblases in vitro. In liposomes, opsin scrambles lipids at a unitary rate of >100,000 per second. Atomistic molecular dynamics simulations of opsin in a lipid membrane reveal conformational transitions that expose a polar groove between transmembrane helices 6 and 7. This groove enables transbilayer lipid movement, conceptualized as the swiping of a credit card (lipid) through a card reader (GPCR). Conformational changes that facilitate scrambling are distinct from those associated with GPCR signaling. In this review, we discuss the physiological significance of GPCR scramblase activity and the modes of its regulation in cells. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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