scholarly journals Regulation of PDF Receptor signaling controlling daily locomotor rhythms in Drosophila

2022 ◽  
Author(s):  
Weihua Li ◽  
Jennifer Trigg ◽  
Paul H Taghert
Keyword(s):  
Surface Expression ◽  
G Protein Coupled Receptors ◽  
Signaling Cascades ◽  
Loss Of Function ◽  
Rhythmic Behavior ◽  
Second Messenger Signaling ◽  
Locomotor Rhythms ◽  
G Protein Coupled

G protein-coupled receptors (GPCRs) trigger second messenger signaling cascades following activation by cognate ligands. GPCR signaling ceases following receptor desensitization or uncoupling from G proteins. Each day and in conjunction with ambient daylight conditions, neuropeptide PDF regulates the phase and amplitude of locomotor activity rhythms in Drosophila through its receptor, a Family B GPCR. Its time of action – when it starts signaling and when it stops – must change every day to following changing day lengths. We studied the process by which PDF Receptor (PDFR) signaling turns off in vivo, by modifying as many as half of the 28 potential sites of phosphorylation in its C terminal tail. We report that many such sites are conserved evolutionarily, and that in general their conversion to a non-phosphorylatable residue (alanine) creates a specific behavioral syndrome opposite to loss of function phenotypes previously described for pdfr. Such “gain of function” pdfr phenotypes include increases in the amplitudes of both Morning and Evening behavioral peaks as well as multi-hour delays of their phases. Such effects were most clearly associated with a few specific serine residues, and were seen following alanine-conversion of as few as one or two residues. The behavioral phenotypes produced by these PDFR sequence variants are not a consequence of changes to the pharmacological properties or of changes in their surface expression, as measured in vitro. We conclude that the mechanisms underlying termination of PDFR signaling are complex and central to an understanding of how this critical neuropeptide modulates daily rhythmic behavior.

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 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 cAMP levels regulate macrophage alternative activation marker expression

2020 ◽  
pp. 175342592097508
Author(s):  
Swamy Polumuri ◽  
Darren J Perkins ◽  
Stefanie N Vogel
Keyword(s):  
G Protein Coupled Receptors ◽  
Alternative Activation ◽  
Marker Genes ◽  
Marker Expression ◽  
Inflammatory Milieu ◽  
G Protein Coupled ◽  
Camp Levels ◽  
Dependent Pathway

The capacity for macrophages to polarize into distinct functional activation states (e.g., M1, M2) is critical to tune an inflammatory response to the relevant infection or injury. Alternative or M2 polarization of macrophages is most often achieved in vitro in response to IL-4/IL-13 and results in the transcriptional up-regulation of a constellation of characteristic M2 marker genes. In vivo, additional signals from the inflammatory milieu can further increase or decrease M2 marker expression. Particularly, activation of cAMP-generating G protein-coupled receptors is reported to increase M2 markers, but whether this is strictly dependent upon cAMP production is unclear. We report herein that increased cAMP alone can increase IL-4-dependent M2 marker expression through a PKA/C/EBPβ/CREB dependent pathway in murine macrophages.

scholarly journals Polyciliation of GnRH Neurons in Vivo and in Vitro

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A548-A549
Author(s):  
Kathryn M Brewer ◽  
Ruchi Bansal ◽  
Staci E Engle ◽  
Patrick J Antonellis ◽  
Theodore R Cummins ◽  
...  
Keyword(s):  
Primary Cilia ◽  
Small Subset ◽  
Loss Of Function ◽  
Hpg Axis ◽  
Gnrh Neurons ◽  
Gonadotrophin Releasing Hormone ◽  
G Protein Coupled ◽  
Ciliary Localization

Abstract Puberty and reproduction are initiated and controlled through the hypothalamic-pituitary-gonadal (HPG) axis. A critical surge of luteinizing hormone (LH) and follicle stimulating hormone (FSH) are released from the anterior pituitary upon release of gonadotrophins from gonadotrophin releasing hormone (GnRH) neurons. Thus, GnRH neurons are key regulators of the HPG axis. GnRH neurons become active when kisspeptin (Kiss1) neuropeptides are released from neurons in the arcuate nucleus. Kiss1 binds to the Kiss1 receptor (Kiss1R), a G-protein coupled receptor (GPCR) which localizes to the primary cilia of GnRH neurons. Loss-of-function mutations of Kiss1R cause hypogonadism in mouse and human models while gain-of-function mutations are associated with precocious puberty. Interestingly, the subset of GnRH neurons that express Kiss1R are observed to be polyciliated, possessing more than one primary cilia, an uncommon property as most neurons only possess a single, primary cilium. The mechanism and conditions leading to GnRH neuron polyciliation are unknown. It is also unclear if multiple cilia impact Kiss1R or other GPCR signaling in these neurons. Here, we utilize cultured mouse primary hypothalamic neurons to begin addressing some of these questions. We have confirmed with qPCR that the ligands GnRH and Kiss1, as well as Kiss1R, are all expressed in these cultures. Surprisingly, when treated with Kiss1 and GnRH ligands we observed a small subset of polyciliated neurons compared to vehicle treated neurons. These observations mirror what is seen during sexual maturation in vivo and suggest that our model system may help elucidate fundamental questions about how ciliary localization of Kiss1r and other GPCRs participate in initiation of puberty and regulation of reproduction. Future studies will focus on the mechanisms of polyciliation and the conditions needed to induce the formation of new cilia in GnRH neurons. Investigating neuronal polyciliation could provide insights into new signaling paradigm in hypogonadism and HPG signaling.

Engineered GPCRs as Tools to Modulate Signal Transduction

Physiology ◽  
2008 ◽  
Vol 23 (6) ◽  
pp. 313-321 ◽  
Author(s):  
Ying Pei ◽  
Sarah C. Rogan ◽  
Feng Yan ◽  
Bryan L. Roth
Keyword(s):  
Signal Transduction ◽  
Signaling Pathways ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
Designer Drugs ◽  
Modulate Signal ◽  
Synthetic Drug ◽  
G Protein Coupled

Different families of G-protein-coupled receptors (GPCRs) have been engineered to provide exclusive control over the activation of these receptors and thus to understand better the consequences of their signaling in vitro and in vivo. These engineered receptors, named RASSLs (receptors activated solely by synthetic ligands) and DREADDs (designer receptors exclusively activated by designer drugs), are insensitive to their endogenous ligands but can be activated by synthetic drug-like compounds. Currently, the existing RASSLs and DREADDs cover the Gi, Gq, and Gs signaling pathways. These modified GPCRs can be utilized as ideal tools to study GPCR functions selectively in specific cellular populations.

scholarly journals Adenovirus-Mediated In Vivo Silencing of Anaphylatoxin Receptor C5aR

2006 ◽  
Vol 2006 ◽  
pp. 1-9 ◽  
Author(s):  
Lei Sun ◽  
Hongwei Gao ◽  
Vidya J. Sarma ◽  
Ren-feng Guo ◽  
Peter A. Ward
Keyword(s):  
G Protein Coupled Receptors ◽  
Mouse Lung ◽  
Transcriptional Level ◽  
Shrna Expression ◽  
C5a Receptor ◽  
Immunological Diseases ◽  
Short Hairpin Rnas ◽  
G Protein Coupled

C5a, one of the most potent inflammatory peptides, induces its inflammatory functions by interacting with C5a receptor (C5aR) that belongs to the rhodopsin family of seven-transmembrane G protein-coupled receptors. C5a/C5aR signaling has been implicated in the pathogenesis of many inflammatory and immunological diseases such as sepsis and acute lung injury. Widespread upregulation of C5aR has been seen at both the protein level and transcriptional level under pathological conditions. Here, we show that C5aR gene expression can be specifically suppressed by siRNA, both in vitro and in vivo. A panel of chemically siRNA oligonucleotides was first synthesized to identify the functional siRNA sequences. The short hairpin RNAs (shRNAs) were also designed, cloned, and tested for the silencing effects in C5aR transfected cells. The effective shRNA expression cassettes were then transferred to an adenovirus DNA vector. ShRNA-expressing adenoviruses were intratracheally administered into mouse lung, and a significant in vivo silencing of C5aR was obtained four days after administration. Thus, C5aR shRNA-expressing adenoviruses appear to be an alternative strategy for the treatment of complement-induced disorders.

scholarly journals Towards in vivo imaging of functionally active 5-HT1A receptors in schizophrenia: concepts and challenges

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Oriane Razakarivony ◽  
Adrian Newman-Tancredi ◽  
Luc Zimmer
Keyword(s):  
Psychiatric Disorders ◽  
Cognitive Processes ◽  
G Protein Coupled Receptors ◽  
Research Paradigms ◽  
New Research ◽  
New Generation ◽  
G Protein Coupled

AbstractThe serotonin 5-HT1A receptor has attracted wide attention as a target for treatment of psychiatric disorders. Although this receptor is important in the pharmacological mechanisms of action of new-generation antipsychotics, its characterization remains incomplete. Studies based on in vitro molecular imaging on brain tissue by autoradiography, and more recently in vivo PET imaging, have not yielded clear results, in particular due to the limitations of current 5-HT1A radiotracers, which lack specificity and/or bind to all 5-HT1A receptors, regardless of their functional status. The new concept of PET neuroimaging of functionally active G-protein-coupled receptors makes it possible to revisit PET brain exploration by enabling new research paradigms. For the 5-HT1A receptor it is now possible to use [18F]-F13640, a 5-HT1A receptor radioligand with high efficacy agonist properties, to specifically visualize and quantify functionally active receptors, and to relate this information to subjects’ pathophysiological or pharmacological state. We therefore propose imaging protocols to follow changes in the pattern of functional 5-HT1A receptors in relation to mood deficits or cognitive processes. This could allow improved discrimination of different schizophrenia phenotypes and greater understanding of the basis of therapeutic responses to antipsychotic drugs. Finally, as well as targeting functionally active receptors to gain insights into the role of 5-HT1A receptors, the concept can also be extended to the study of other receptors involved in the pathophysiology or therapy of psychiatric disorders.

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