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Lohse MJ, Bock A, Zaccolo M. G Protein-Coupled Receptor Signaling: New Insights Define Cellular Nanodomains. Annu Rev Pharmacol Toxicol 2024; 64:387-415. [PMID: 37683278 DOI: 10.1146/annurev-pharmtox-040623-115054] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/10/2023]
Abstract
G protein-coupled receptors are the largest and pharmacologically most important receptor family and are involved in the regulation of most cell functions. Most of them reside exclusively at the cell surface, from where they signal via heterotrimeric G proteins to control the production of second messengers such as cAMP and IP3 as well as the activity of several ion channels. However, they may also internalize upon agonist stimulation or constitutively reside in various intracellular locations. Recent evidence indicates that their function differs depending on their precise cellular localization. This is because the signals they produce, notably cAMP and Ca2+, are mostly bound to cell proteins that significantly reduce their mobility, allowing the generation of steep concentration gradients. As a result, signals generated by the receptors remain confined to nanometer-sized domains. We propose that such nanometer-sized domains represent the basic signaling units in a cell and a new type of target for drug development.
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Affiliation(s)
- Martin J Lohse
- ISAR Bioscience Institute, Planegg/Munich, Germany;
- Rudolf Boehm Institute of Pharmacology and Toxicology, Leipzig University, Leipzig, Germany
| | - Andreas Bock
- Rudolf Boehm Institute of Pharmacology and Toxicology, Leipzig University, Leipzig, Germany
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics and National Institute for Health and Care Research Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom;
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2
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Acharya S, Petzel EA, Hales KE, Underwood KR, Swanson KC, Bailey EA, Cammack KM, Brake DW. Effects of long-term postgastric infusion of casein or glutamic acid on small intestinal starch digestion and energy balance in cattle. J Anim Sci 2023; 101:skac329. [PMID: 36592759 PMCID: PMC9831104 DOI: 10.1093/jas/skac329] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 10/08/2022] [Indexed: 01/04/2023] Open
Abstract
The objective of this experiment was to evaluate effects of postruminal flows of casein or glutamic acid on small intestinal starch digestion and to quantify changes in energy and nutrient balance. Twenty-four steers (body weight = 179 ± 4 kg) were duodenally infused with raw cornstarch (1.46 ± 0.04 kg/d) and either 413 ± 7.0 g casein/d, 121 ± 3.6 g glutamic acid/d or water (control). Measures of small intestinal starch digestion and nutrient excretion were collected across 4 d after 42 d of infusion and measures of respiration via indirect calorimetry were collected across 2 d after 48 d of infusion. Ileal starch flow was least among calves provided casein, but ileal starch flow was not different between glutamic acid or control. Small intestinal starch digestion tended to be greatest among calves provided casein, least for glutamic acid and intermediate for control. Casein increased ileal flow of ethanol soluble oligosaccharides compared to glutamic acid and control. Large intestinal starch digestion was not different among treatments. By design, N intake was greatest among cattle provided casein, intermediate among calves provided glutamic acid and least for control. Nitrogen retention was greater in response to casein compared to control and glutamic acid. Intake of gross energy from feed was similar across treatments, and gross energy from infusate was greatest for casein, intermediate for glutamic acid and least for control. Variation in gross energy intake from feed resulted in no difference in overall gross energy intake across treatments. Similar to measures of small intestinal starch digestion and N retention, casein increased calories of digestible energy and metabolizable energy, compared to glutamic acid and control, which did not differ. Postruminal infusions did not influence methane production, but heat production was greatest in steers infused with casein, intermediate for steers provided glutamic acid, and least for control. Overall, amounts of energy retained by casein tended to be nearly 34% greater than control, but glutamic acid had no impact on energy balance. Improvement in small intestinal starch digestion in response to casein increased energy and N retained; however, glutamic acid did not influence small intestinal starch digestion and energy or N balance in cattle, which seems to suggest that responses in small intestinal starch digestion to greater postruminal flows of glutamic acid become refractory across greater durations of time.
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Affiliation(s)
- Subash Acharya
- Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA
| | - Emily A Petzel
- Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA
| | - Kristin E Hales
- Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Keith R Underwood
- Department of Animal Science, South Dakota State University, Brookings, SD 57007, USA
| | - Kendall C Swanson
- Department of Animal Sciences, North Dakota State University, Fargo, ND 58102, USA
| | - Eric A Bailey
- Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA
| | - Kristi M Cammack
- Department of Animal Science, South Dakota State University, Brookings, SD 57007, USA
| | - Derek W Brake
- Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA
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3
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Zhu Y, Huang D, Zhao Z, Lu C. Bioinformatic analysis identifies potential key genes of epilepsy. PLoS One 2021; 16:e0254326. [PMID: 34555062 PMCID: PMC8459949 DOI: 10.1371/journal.pone.0254326] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/31/2021] [Indexed: 12/19/2022] Open
Abstract
Background Epilepsy is one of the most common brain disorders worldwide. It is usually hard to be identified properly, and a third of patients are drug-resistant. Genes related to the progression and prognosis of epilepsy are particularly needed to be identified. Methods In our study, we downloaded the Gene Expression Omnibus (GEO) microarray expression profiling dataset GSE143272. Differentially expressed genes (DEGs) with a fold change (FC) >1.2 and a P-value <0.05 were identified by GEO2R and grouped in male, female and overlapping DEGs. Functional enrichment analysis and Protein-Protein Interaction (PPI) network analysis were performed. Results In total, 183 DEGs overlapped (77 ups and 106 downs), 302 DEGs (185 ups and 117 downs) in the male dataset, and 750 DEGs (464 ups and 286 downs) in the female dataset were obtained from the GSE143272 dataset. These DEGs were markedly enriched under various Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) terms. 16 following hub genes were identified based on PPI network analysis: ADCY7, C3AR1, DEGS1, CXCL1 in male-specific DEGs, TOLLIP, ORM1, ELANE, QPCT in female-specific DEGs and FCAR, CD3G, CLEC12A, MOSPD2, CD3D, ALDH3B1, GPR97, PLAUR in overlapping DEGs. Conclusion This discovery-driven study may be useful to provide a novel insight into the diagnosis and treatment of epilepsy. However, more experiments are needed in the future to study the functional roles of these genes in epilepsy.
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Affiliation(s)
- Yike Zhu
- Department of Respiratory Medicine, Hainan General Hospital, Haikou, China
| | - Dan Huang
- Department of Neurology, Hainan General Hospital, Haikou, China
| | - Zhongyan Zhao
- Department of Neurology, Hainan General Hospital, Haikou, China
| | - Chuansen Lu
- Department of Neurology, Hainan General Hospital, Haikou, China
- * E-mail:
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4
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Olianas MC, Dedoni S, Onali P. Cannabinoid CB 1 and CB 2 receptors differentially regulate TNF-α-induced apoptosis and LPA 1-mediated pro-survival signaling in HT22 hippocampal cells. Life Sci 2021; 276:119407. [PMID: 33794254 DOI: 10.1016/j.lfs.2021.119407] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/02/2021] [Accepted: 03/15/2021] [Indexed: 01/11/2023]
Abstract
AIMS The aim of the study was to investigate the interaction between cannabinoid CB1/CB2 and lysophosphatidic acid (LPA) receptors in controlling neuronal signaling and fate. METHODS HT22 hippocampal cells were treated with different cannabinoid and LPA receptor agonists and antagonists. Western blot and immunofluorescence microscopy were used to study intracellular signaling and the expression of apoptotic markers. Cell viability was determined by a luminescence assay. KEY FINDINGS Cannabinoid agonists induced activation of both ERK1/2 and p38 MAP kinases. The effects of the CB1/CB2 receptor agonist HU210 were antagonized by the CB1 antagonist rimonabant, whereas the responses to the CB2 agonist JWH133 were blocked by the CB2 antagonist SR144528. HU210 reduced the apoptotic cell death induced by the pro-inflammatory cytokine TNF-α, whereas JWH133 enhanced the cytokine cytotoxicity. Blockade of ERK1/2 and p38 MAPK activation abrogated the HU210 pro-survival and the JWH133 pro-apoptotic effects, respectively. HU210 and the endocannabinoid anandamide, but not JWH133, potentiated ERK1/2 stimulation by LPA and the tricyclic antidepressant amitriptyline acting through the LPA1 receptor. HU210 enhanced amitriptyline-stimulated CREB phosphorylation and protection against TNF-α-induced apoptosis, whereas JWH133 had no effect. ERK1/2 stimulation by either HU210 or amitriptyline was dependent on fibroblast growth factor receptor (FGF-R) kinase activity and the combination of the two stimulants induced FGF-R phosphorylation. Moreover, the CB1 receptor was found to co-immunoprecipitate with the LPA1 receptor. CONCLUSIONS In HT22 hippocampal cells CB1 and CB2 receptors differentially regulate TNF-α-induced apoptosis and CB1 receptors positively interact with amitriptyline-stimulated LPA1 in promoting FGF-R-mediated ERK1/2 signaling and neuroprotection.
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Affiliation(s)
- Maria C Olianas
- Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Simona Dedoni
- Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Pierluigi Onali
- Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy.
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5
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Parsons RL, May V. PACAP-Induced PAC1 Receptor Internalization and Recruitment of Endosomal Signaling Regulate Cardiac Neuron Excitability. J Mol Neurosci 2019; 68:340-347. [PMID: 30054797 PMCID: PMC6348136 DOI: 10.1007/s12031-018-1127-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 07/18/2018] [Indexed: 11/27/2022]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP, Adcyap1) activation of PAC1 receptors (Adcyap1r1) significantly increases excitability of guinea pig cardiac neurons. This modulation of excitability is mediated in part by plasma membrane G protein-dependent activation of adenylyl cyclase and downstream signaling cascades, as well as by endosomal signaling mechanisms. PACAP/PAC1 receptor-mediated activation of plasma membrane adenylyl cyclase (AC) and the resulting increase in cellular cAMP enhances a hyperpolarization-induced nonselective cationic current Ih, which contributes to the PACAP-induced increase in cardiac neuron excitability. Further, PACAP-mediated AC/cAMP/PKA downstream signaling also appears to enhance cardiac neuron IT to facilitate the excitatory responses. PACAP activation of PAC1 receptors rapidly stimulates receptor internalization, and reducing ambient temperature or treatments with the clathrin inhibitor Pitstop2 or the dynamin I/II inhibitor dynasore to block endocytic events can suppress PACAP-enhanced neuronal excitability. Thus, endocytosis inhibitors essentially eliminate PACAP-enhanced excitability suggesting that endosomal platforms represent a primary signaling mechanism. Endosomal signaling is associated canonically with ERK activation and in accord, PACAP-enhanced cardiac neuron excitability is reduced by MEK inhibitor pretreatments. PACAP activation of MEK/ERK signaling can enhance currents through voltage-dependent Nav1.7 channels. Hence, PACAP-induced PAC1 receptor internalization/endosomal signaling, recruitment of MEK/ERK signaling, and modulation of Nav1.7 are implicated as key mechanisms contributing to the PACAP-enhanced neuronal excitability. PACAP/PAC1 receptor-mediated endosomal ERK signaling in central circuits can play key roles in development of chronic pain and anxiety-related responses; thus, PAC1 endosomal signaling likely participates in a variety of homeostatic responses within neuronal circuits in the CNS.
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Affiliation(s)
- Rodney L Parsons
- Departmental of Neurological Sciences, Robert Larner College of Medicine, University of Vermont, Burlington, VT, USA.
| | - Victor May
- Departmental of Neurological Sciences, Robert Larner College of Medicine, University of Vermont, Burlington, VT, USA
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6
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Human nonvisual opsin 3 regulates pigmentation of epidermal melanocytes through functional interaction with melanocortin 1 receptor. Proc Natl Acad Sci U S A 2019; 116:11508-11517. [PMID: 31097585 DOI: 10.1073/pnas.1902825116] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Opsins form a family of light-activated, retinal-dependent, G protein-coupled receptors (GPCRs) that serve a multitude of visual and nonvisual functions. Opsin 3 (OPN3 or encephalopsin), initially identified in the brain, remains one of the few members of the mammalian opsin family with unknown function and ambiguous light absorption properties. We recently discovered that OPN3 is highly expressed in human epidermal melanocytes (HEMs)-the skin cells that produce melanin. The melanin pigment is a critical defense against ultraviolet radiation (UVR), and its production is mediated by the Gαs-coupled melanocortin 1 receptor (MC1R). The physiological function and light sensitivity of OPN3 in melanocytes are yet to be determined. Here, we show that in HEMs, OPN3 acts as a negative regulator of melanin production by modulating the signaling of MC1R. OPN3 negatively regulates the cyclic adenosine monophosphate (cAMP) response evoked by MC1R via activation of the Gαi subunit of G proteins, thus decreasing cellular melanin levels. In addition to their functional relationship, OPN3 and MC1R colocalize at both the plasma membrane and in intracellular structures, and can form a physical complex. Remarkably, OPN3 can bind retinal, but does not mediate light-induced signaling in melanocytes. Our results identify a function for OPN3 in the regulation of the melanogenic pathway in epidermal melanocytes; we have revealed a light-independent function for the poorly characterized OPN3 and a pathway that greatly expands our understanding of melanocyte and skin physiology.
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7
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Wang J, Wang X, Chen X, Lu S, Kuang Y, Fei J, Wang Z. Gpr97/Adgrg3 ameliorates experimental autoimmune encephalomyelitis by regulating cytokine expression. Acta Biochim Biophys Sin (Shanghai) 2018; 50:666-675. [PMID: 29860267 DOI: 10.1093/abbs/gmy060] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Indexed: 02/07/2023] Open
Abstract
Multiple sclerosis and its primary animal model, experimental autoimmune encephalomyelitis (EAE), are inflammatory diseases of the central nervous system (CNS) characterized by immune-mediated demyelination and neurodegeneration that may be mediated by inhibition of the nuclear factor-κB (NF-κB) signaling pathway. Gpr97, encoded by Adgrg3, has been reported to regulate the activity of NF-κB. In this study, using a previously established Adgrg3-knockout mouse model, we investigated the roles of Gpr97 in the development of autoimmune CNS disease in mice. We found a marked increase in the expression of Adgrg3 in spinal cords of mice with EAE. Adgrg3-deficient (Adgrg3-/-) mice with EAE exhibited increases in peak severity and the cumulative disease score compared with littermate controls, followed by a notable increase of leukocyte infiltration and more extensive demyelination. The percentages of Th1/Th17 cells in the CNS were significantly increased in Adgrg3-/- mice and accompanied by high levels of interleukin (IL)-6, interferon-γ, tumor necrosis factor-α, and IL-17. An in vitro culture assay verified that Gpr97 regulated proinflammatory cytokine production. Taken together, our results show that Gpr97 plays an important role in the development of EAE and may have a therapeutic potential for the treatment of CNS autoimmunity.
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Affiliation(s)
- Jinjin Wang
- Shanghai Research Center for Model Organisms, Shanghai, China
| | - Xiyi Wang
- Department of Medical Genetics, Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China
| | - Xuejiao Chen
- Department of Medical Genetics, Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China
| | - Shunyuan Lu
- State Key Laboratory of Medical Genomics, Research Center for Experimental Medicine of Rui-Jin Hospital, Shanghai, China
| | - Ying Kuang
- Shanghai Research Center for Model Organisms, Shanghai, China
| | - Jian Fei
- Shanghai Research Center for Model Organisms, Shanghai, China
| | - Zhugang Wang
- Shanghai Research Center for Model Organisms, Shanghai, China
- Department of Medical Genetics, Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China
- State Key Laboratory of Medical Genomics, Research Center for Experimental Medicine of Rui-Jin Hospital, Shanghai, China
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8
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Wang D. The essential role of G protein-coupled receptor (GPCR) signaling in regulating T cell immunity. Immunopharmacol Immunotoxicol 2018; 40:187-192. [PMID: 29433403 DOI: 10.1080/08923973.2018.1434792] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
AIM The aim of this paper is to clarify the critical role of GPCR signaling in T cell immunity. METHODS The G protein-coupled receptors (GPCRs) are the most common targets in current pharmaceutical industry, and represent the largest and most versatile family of cell surface communicating molecules. GPCRs can be activated by a diverse array of ligands including neurotransmitters, chemokines as well as sensory stimuli. Therefore, GPCRs are involved in many key cellular and physiological processes, such as sense of light, taste and smell, neurotransmission, metabolism, endocrine and exocrine secretion. In recent years, GPCRs have been found to play an important role in immune system. T cell is an important type of immune cell, which plays a central role in cell-mediated immunity. A variety of GPCRs and their signaling mediators (RGS proteins, GRKs and β-arrestin) have been found to express in T cells and involved T cell-mediated immunity. We will summarize the role of GPCR signaling and their regulatory molecules in T cell activation, homeostasis and function in this article. RESULTS GPCR signaling plays an important role in T cell activation, homeostasis and function. CONCLUSION GPCR signaling is critical in regulating T cell immunity.
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Affiliation(s)
- Dashan Wang
- a Molecular Biology Research Center, Key Medical Health Laboratory for Laboratory Medicine of Shandong Province, Department of Laboratory Medicine , Shandong Medical College , Linyi , Shandong , China
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9
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Busquets-Garcia A, Bains J, Marsicano G. CB 1 Receptor Signaling in the Brain: Extracting Specificity from Ubiquity. Neuropsychopharmacology 2018; 43:4-20. [PMID: 28862250 PMCID: PMC5719111 DOI: 10.1038/npp.2017.206] [Citation(s) in RCA: 192] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 07/22/2017] [Accepted: 08/14/2017] [Indexed: 02/07/2023]
Abstract
Endocannabinoids (eCBs) are amongst the most ubiquitous signaling molecules in the nervous system. Over the past few decades, observations based on a large volume of work, first examining the pharmacological effects of exogenous cannabinoids, and then the physiological functions of eCBs, have directly challenged long-held and dogmatic views about communication, plasticity and behavior in the central nervous system (CNS). The eCBs and their cognate cannabinoid receptors exhibit a number of unique properties that distinguish them from the widely studied classical amino-acid transmitters, neuropeptides, and catecholamines. Although we now have a loose set of mechanistic rules based on experimental findings, new studies continue to reveal that our understanding of the eCB system (ECS) is continuously evolving and challenging long-held conventions. Here we will briefly summarize findings on the current canonical view of the 'ECS' and will address novel aspects that reveal how a nearly ubiquitous system can determine highly specific functions in the brain. In particular, we will focus on findings that push for an expansion of our ideas around long-held beliefs about eCB signaling that, while clearly true, may be contributing to an oversimplified perspective on how cannabinoid signaling at the microscopic level impacts behavior at the macroscopic level.
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Affiliation(s)
- Arnau Busquets-Garcia
- INSERM U1215, NeuroCentre Magendie, Team ‘Endocannabinoids and Neuroadaptation’, Bordeaux, France
- Université de Bordeaux, Bordeaux, France
| | - Jaideep Bains
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Giovanni Marsicano
- INSERM U1215, NeuroCentre Magendie, Team ‘Endocannabinoids and Neuroadaptation’, Bordeaux, France
- Université de Bordeaux, Bordeaux, France
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10
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Xu M, Hong R, Zhang X, Zou H, Zhang Y, Hou Z, Wang L. CysLT1 receptor antagonist alleviates pathogenesis of collagen-induced arthritis mouse model. Oncotarget 2017; 8:108418-108429. [PMID: 29312540 PMCID: PMC5752453 DOI: 10.18632/oncotarget.22664] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 11/07/2017] [Indexed: 01/11/2023] Open
Abstract
Cysteinyl leukotrienes (CysLTs) play a key role in inflammatory diseases such as asthma and their receptors’ antagonists are currently used as anti-asthmatic drugs. CysLTs have also been found to participate in other inflammatory reactions. Here, we reported that in rheumatoid arthritis (RA) animals model, collagen-induced arthritis, (CIA), CysLT1, a receptor for CysLTs, was up-regulated in hind paw and lymph node, while CysLTs levels in the blood were also higher than normal mice. Montelukast, a drug targeting CysLT1, has been shown to effectively reduce the CIA incidence, peak severity, and cumulative disease scores. Further study indicated that CysLT1 signaling did not affect the differentiation of pathogenic T helper cells. We conclude that montelukast may play important roles in the pathogenesis of CIA, mainly by inducing infiltration of pathogenic T cells, increasing IL-17A secretion and expression of IL-17A, while these effects can be blocked by CysLT1 antagonists. Our findings indicate that antagonist of CysLT1 receptor may be used to treat rheumatoid arthritis.
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Affiliation(s)
- Minwen Xu
- First Affiliated Hospital, Gannan Medical University, Ganzhou, China
| | - Ruiyun Hong
- First Affiliated Hospital, Gannan Medical University, Ganzhou, China
| | - Xiaoli Zhang
- Department of Biotechnology, Gannan Medical University, Ganzhou, China
| | - Hailin Zou
- Department of Biotechnology, Gannan Medical University, Ganzhou, China
| | - Yi Zhang
- Department of Biotechnology, Gannan Medical University, Ganzhou, China
| | - Zhiping Hou
- Department of Biotechnology, Gannan Medical University, Ganzhou, China
| | - Liefeng Wang
- Department of Biotechnology, Gannan Medical University, Ganzhou, China
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11
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Tompkins JD, Clason TA, Buttolph TR, Girard BM, Linden AK, Hardwick JC, Merriam LA, May V, Parsons RL. Src family kinase inhibitors blunt PACAP-induced PAC1 receptor endocytosis, phosphorylation of ERK, and the increase in cardiac neuron excitability. Am J Physiol Cell Physiol 2017; 314:C233-C241. [PMID: 29141923 DOI: 10.1152/ajpcell.00223.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP, Adcyap1) activation of PAC1 receptors ( Adcyap1r1) significantly increases excitability of guinea pig cardiac neurons. This modulation of excitability is mediated in part by plasma membrane G protein-dependent activation of adenylyl cyclase and downstream signaling cascades. However, additional mechanisms responsible for the enhanced excitability are activated following internalization of the PAC1 receptor and endosomal signaling. Src family kinases play critical roles mediating endocytosis of many trophic factor and G protein-coupled receptors. The present study investigated whether Src family kinases also support the PACAP-induced PAC1 receptor internalization, phosphorylation of ERK, and enhanced neuronal excitability. Using human embryonic kidney cells stably expressing a green fluorescent protein-tagged PAC1 receptor, treatment with the Src family kinase inhibitor PP2 (10 µM) markedly reduced the PACAP-induced PAC1 receptor internalization, and in parallel, both PP2 and Src inhibitor 1 (Src-1, 2 µM) reduced ERK activation determined by Western blot analysis. In contrast, Src family kinase inhibitors did not eliminate a PACAP-induced rise in global calcium generated by inositol (1,4,5)-trisphosphate-induced release of calcium from endoplasmic reticulum stores. From confocal analysis of phosphorylated ERK immunostaining, PP2 treatment significantly attenuated PACAP activation of ERK in neurons within cardiac ganglia whole mount preparations. Intracellular recordings demonstrated that PP2 also significantly blunted a PACAP-induced increase in cardiac neuron excitability. These studies demonstrate Src-related kinase activity in PAC1 receptor internalization, activation of MEK/ERK signaling, and regulation of neuronal excitability. The present results provide further support for the importance of PAC1 receptor endosomal signaling as a key mechanism regulating cellular function.
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Affiliation(s)
- John D Tompkins
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California , Los Angeles, California
| | - Todd A Clason
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont , Burlington, Vermont
| | - Thomas R Buttolph
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont , Burlington, Vermont
| | - Beatrice M Girard
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont , Burlington, Vermont
| | - Anne K Linden
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont , Burlington, Vermont
| | | | - Laura A Merriam
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont , Burlington, Vermont
| | - Victor May
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont , Burlington, Vermont
| | - Rodney L Parsons
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont , Burlington, Vermont
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12
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Console-Bram LM, Zhao P, Abood ME. Protocols and Good Operating Practices in the Study of Cannabinoid Receptors. Methods Enzymol 2017; 593:23-42. [PMID: 28750805 DOI: 10.1016/bs.mie.2017.06.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
With the approach of the 30th year since the pioneering discovery of a cannabinoid receptor in rat brain (Devane et al., 1988), the field of cannabinoid pharmacology and physiology has impacted human physiology at multiple levels. The development of highly specific and potent orthosteric ligands, as well as the blossoming field of allosteric ligand development, has placed the endocannabinoid system in the forefront as a modulator of a multitude of physiologic processes. Reproducibility among laboratories is especially important due to the development of novel tools to investigate the role(s) of the endocannabinoid system in human physiology, and to clarify the roles for medicinal marijuana. Any definitive role in normal, or diseased states, must be satisfied through the demonstration of a specific receptor-mediated event. This chapter provides working protocols for the study of cannabinoid receptor-ligand binding, as well as immediate and downstream G protein-dependent signaling assays to assess receptor function.
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Affiliation(s)
- Linda M Console-Bram
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Pingwei Zhao
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
| | - Mary E Abood
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States.
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Hardwick JC, Clason TA, Tompkins JD, Girard BM, Baran CN, Merriam LA, May V, Parsons RL. Recruitment of endosomal signaling mediates the forskolin modulation of guinea pig cardiac neuron excitability. Am J Physiol Cell Physiol 2017; 313:C219-C227. [PMID: 28592413 DOI: 10.1152/ajpcell.00094.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 05/31/2017] [Accepted: 06/01/2017] [Indexed: 12/18/2022]
Abstract
Forskolin, a selective activator of adenylyl cyclase (AC), commonly is used to establish actions of G protein-coupled receptors (GPCRs) that are initiated primarily through activation of AC/cAMP signaling pathways. In the present study, forskolin was used to evaluate the potential role of AC/cAMP, which is a major signaling mechanism for the pituitary adenylate cyclase-activating polypeptide (PACAP)-selective PAC1 receptor, in the regulation of guinea pig cardiac neuronal excitability. Forskolin (5-10 µM) increases excitability in ~60% of the cardiac neurons. The forskolin-mediated increase in excitability was considered related to cAMP regulation of a cyclic nucleotide gated channel or via protein kinase A (PKA)/ERK signaling, mechanisms that have been linked to PAC1 receptor activation. However, unlike PACAP mechanisms, forskolin enhancement of excitability was not significantly reduced by treatment with cesium to block currents through hyperpolarization-activated nonselective cation channels (Ih) or by treatment with PD98059 to block MEK/ERK signaling. In contrast, treatment with the clathrin inhibitor Pitstop2 or the dynamin inhibitor dynasore eliminated the forskolin-induced increase in excitability; treatments with the inactive Pitstop analog or PP2 treatment to inhibit Src-mediated endocytosis mechanisms were ineffective. The PKA inhibitor KT5702 significantly suppressed the forskolin-induced change in excitability; further, KT5702 and Pitstop2 reduced the forskolin-stimulated MEK/ERK activation in cardiac neurons. Collectively, the present results suggest that forskolin activation of AC/cAMP/PKA signaling leads to the recruitment of clathrin/dynamin-dependent endosomal transduction cascades, including MEK/ERK signaling, and that endosomal signaling is the critical mechanism underlying the forskolin-induced increase in cardiac neuron excitability.
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Affiliation(s)
| | - Todd A Clason
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont, Burlington, Vermont
| | - John D Tompkins
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California; and
| | - Beatrice M Girard
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont, Burlington, Vermont
| | - Caitlin N Baran
- Department of Medicine, Robert Larner MD College of Medicine, University of Vermont, Burlington, Vermont
| | - Laura A Merriam
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont, Burlington, Vermont
| | - Victor May
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont, Burlington, Vermont
| | - Rodney L Parsons
- Department of Neurological Sciences, Robert Larner MD College of Medicine, University of Vermont, Burlington, Vermont;
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Qin C, Zhou J, Gao Y, Lai W, Yang C, Cai Y, Chen S, Du C. Critical Role of P2Y12 Receptor in Regulation of Th17 Differentiation and Experimental Autoimmune Encephalomyelitis Pathogenesis. THE JOURNAL OF IMMUNOLOGY 2017; 199:72-81. [DOI: 10.4049/jimmunol.1601549] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 04/24/2017] [Indexed: 11/19/2022]
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15
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Abstract
BACKGROUND It has been demonstrated that κ-opioid receptor agonists can reduce hypoxia-ischemia brain injury in animal models. However, it is unclear how the κ-opioid receptor responds to hypoxia-ischemia. In the current study, the authors used an in vitro model of oxygen-glucose deprivation and reoxygenation to explore how κ-opioid receptors respond to hypoxia and reoxygenation. METHODS Mouse neuroblastoma Neuro2A cells were stably transfected with mouse κ-opioid receptor-tdTomato fusion protein or Flag-tagged mouse κ-opioid receptor, divided into several groups (n = 6 to 12), and used to investigate the κ-opioid receptor movement. Observations were performed under normal oxygen, at 30 min to 1 h after oxygen-glucose deprivation and at 1 h after reoxygenation using high-resolution imaging techniques including immunoelectronmicroscopy in the presence and absence of κ-opioid receptor antagonist, dynamin inhibitors, potassium channel blockers, and dopamine receptor inhibitor. RESULTS Hypoxic conditions caused the κ-opioid receptor to be internalized into the cells. Inhibition of dynamin by Dyngo-4a prevented the receptor internalization. Interestingly, a specific κ-opioid receptor antagonist norbinaltorphimine blocked internalization, suggesting the involvement of activation of a specific κ-opioid receptor. κ-Opioid receptor internalization appears to be reversed by reoxygenation. Quantities of intracellular κ-opioid receptor-associated gold particles as demonstrated by immunoelectron microscopy were increased from 37 to 85% (P < 0.01) after oxygen-glucose deprivation. Potassium channel blockers and dopamine receptor inhibitor failed to block hypoxia-induced κ-opioid receptor internalization. CONCLUSIONS Hypoxia induces reversible κ-opioid receptor internalization, which was inhibited by selective κ-opioid receptor antagonists or dynamin inhibitor, and can be reversed by reoxygenation in neuroblastoma cells, indicating the modulating effects between κ-opioid receptor and hypoxia via κ-opioid receptor activation and the dynamin-dependent mechanism.
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16
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Szepanowski F, Kieseier BC. Targeting lysophospholipid signaling as a therapeutic approach towards improved peripheral nerve regeneration. Neural Regen Res 2017; 11:1754-1755. [PMID: 28123411 PMCID: PMC5204223 DOI: 10.4103/1673-5374.194720] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Fabian Szepanowski
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Bernd C Kieseier
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
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17
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Brailoiu GC, Brailoiu E. Modulation of Calcium Entry by the Endo-lysosomal System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:423-47. [PMID: 27161239 DOI: 10.1007/978-3-319-26974-0_18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Endo-lysosomes are acidic organelles that besides the role in macromolecules degradation, act as intracellular Ca(2+) stores. Nicotinic acid adenine dinucleotide phosphate (NAADP), the most potent Ca(2+)-mobilizing second messenger, produced in response to agonist stimulation, activates Ca(2+)-releasing channels on endo-lysosomes and modulates a variety of cellular functions. NAADP-evoked signals are amplified by Ca(2+) release from endoplasmic reticulum, via the recruitment of inositol 1,4,5-trisphosphate and/or ryanodine receptors through a Ca(2+)-induced Ca(2+)- release (CICR) mechanism. The endo-lysosomal Ca(2+) channels activated by NAADP were recently identified as the two-pore channels (TPCs). In addition to TPCs, endo-lysosomes express another distinct family of Ca(2+)- permeable channels, namely the transient receptor potential mucolipin (TRPML) channels, functionally distinct from TPCs. TPCs belong to the voltage-gated channels, resembling voltage-gated Na(+) and Ca(2+) channels. TPCs have important roles in vesicular fusion and trafficking, in triggering a global Ca(2+) signal and in modulation of the membrane excitability. Depletion of acidic Ca(2+) stores has been shown to activate store-operated Ca(2+) entry in human platelets and mouse pancreatic β-cells. In human platelets, Ca(2+) influx in response to acidic stores depletion is facilitated by the tubulin-cytoskeleton and occurs through non-selective cation channels and transient receptor potential canonical (TRPC) channels. Emerging evidence indicates that activation of intracellular receptors, situated on endo-lysosomes, elicits canonical and non-canonical signaling mechanisms that involve CICR and activation of non-selective cation channels in plasma membrane. The ability of endo-lysosomal Ca(2+) stores to modulate the Ca(2+) release from other organelles and the Ca(2+) entry increases the diversity and complexity of cellular signaling mechanisms.
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Affiliation(s)
- G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Jefferson School of Pharmacy, Thomas Jefferson University, 901 Walnut St, Rm 916, Philadelphia, PA, 19107, USA.
| | - Eugen Brailoiu
- Center for Substance Abuse Research, Temple University School of Medicine, 3500 N. Broad Street, Room 848, Philadelphia, PA, 19140, USA
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18
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Martin BR, Lambert NA. Activated G Protein Gαs Samples Multiple Endomembrane Compartments. J Biol Chem 2016; 291:20295-20302. [PMID: 27528603 DOI: 10.1074/jbc.m116.729731] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Indexed: 11/06/2022] Open
Abstract
Heterotrimeric G proteins are localized to the plasma membrane where they transduce extracellular signals to intracellular effectors. G proteins also act at intracellular locations, and can translocate between cellular compartments. For example, Gαs can leave the plasma membrane and move to the cell interior after activation. However, the mechanism of Gαs translocation and its intracellular destination are not known. Here we use bioluminescence resonance energy transfer (BRET) to show that after activation, Gαs rapidly associates with the endoplasmic reticulum, mitochondria, and endosomes, consistent with indiscriminate sampling of intracellular membranes from the cytosol rather than transport via a specific vesicular pathway. The primary source of Gαs for endosomal compartments is constitutive endocytosis rather than activity-dependent internalization. Recycling of Gαs to the plasma membrane is complete 25 min after stimulation is discontinued. We also show that an acylation-deacylation cycle is important for the steady-state localization of Gαs at the plasma membrane, but our results do not support a role for deacylation in activity-dependent Gαs internalization.
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Affiliation(s)
- Brent R Martin
- From the Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Nevin A Lambert
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia 30912
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19
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Fingolimod promotes peripheral nerve regeneration via modulation of lysophospholipid signaling. J Neuroinflammation 2016; 13:143. [PMID: 27283020 PMCID: PMC4901498 DOI: 10.1186/s12974-016-0612-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 06/06/2016] [Indexed: 12/26/2022] Open
Abstract
Background The lysophospholipids sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) are pleiotropic signaling molecules with a broad range of physiological functions. Targeting the S1P1 receptor on lymphocytes with the immunomodulatory drug fingolimod has proven effective in the treatment of multiple sclerosis. An emerging body of experimental evidence points to additional direct effects on cells of the central and peripheral nervous system. Furthermore, fingolimod has been reported to reduce LPA synthesis via inhibition of the lysophospholipase autotaxin. Here we investigated whether modulation of particular signaling aspects of S1P as well as LPA by fingolimod might propagate peripheral nerve regeneration in vivo and independent of its anti-inflammatory potency. Methods Sciatic nerve crush was performed in wildtype C57BL/6, in immunodeficient Rag1−/− and Foxn1−/− mice. Analyses were based on walking track analysis and electrophysiology, histology, and cAMP formation. Quantification of different LPA species was performed by liquid chromatography coupled to tandem mass spectrometry. Furthermore, functional consequences of autotaxin inhibition by the specific inhibitor PF-8380 and the impact of fingolimod on early cytokine release in the injured sciatic nerve were investigated. Results Clinical and electrophysiological measures indicated an improvement of nerve regeneration under fingolimod treatment that is partly independent of its anti-inflammatory properties. Fingolimod treatment correlated with a significant elevation of axonal cAMP, a crucial factor for axonal outgrowth. Additionally, fingolimod significantly reduced LPA levels in the injured nerve. PF-8380 treatment correlated with improved myelin thickness. Sciatic nerve cytokine levels were not found to be significantly altered by fingolimod treatment. Conclusions Our findings provide in vivo evidence for direct effects of fingolimod on cells of the peripheral nervous system that may propagate nerve regeneration via a dual mode of action, differentially affecting axonal outgrowth and myelination by modulating relevant aspects of S1P and LPA signaling.
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20
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Fabbri E, Moon TW. Adrenergic signaling in teleost fish liver, a challenging path. Comp Biochem Physiol B Biochem Mol Biol 2015; 199:74-86. [PMID: 26482086 DOI: 10.1016/j.cbpb.2015.10.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Revised: 09/09/2015] [Accepted: 10/12/2015] [Indexed: 01/15/2023]
Abstract
Adrenergic receptors or adrenoceptors (ARs) belong to the huge family of G-protein coupled receptors (GPCRs) that have been well characterized in mammals primarily because of their importance as therapeutic drug targets. ARs are found across vertebrates and this review examines the path to identify and characterize these receptors in fish with emphasis on hepatic metabolism. The absence of reliable and specific pharmacological agents led investigators to define the fish hepatic AR system as relying solely on a β2-AR, cAMP-dependent signaling transduction pathway. The use of calcium-radiometric imaging, purified membranes for ligand-binding studies, and perifused rather than static cultured fish hepatocytes, unequivocally demonstrated that both α1- and β2-AR signaling systems existed in the fish liver consistent with studies in mammals. Additionally, the use of molecular tools and phylogenetic analysis clearly demonstrated the existence of multiple AR-types and -subtypes in hepatic and other tissues of a number of fish species. This review also examines the use of β-blockers as pharmaceuticals and how these drugs that are now in the aquatic environment may be impacting aquatic species including fish and some invertebrates. Clearly there is a large conservation of structure and function within the AR system of vertebrates but there remain a number of key questions that need to be addressed before a clear understanding of these systems can be resolved.
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Affiliation(s)
- Elena Fabbri
- University of Bologna, Department of Biological, Geological and Environmental Sciences Unit of Ravenna, via S. Alberto 163, 48124 Ravenna, Italy.
| | - Thomas W Moon
- University of Ottawa, Department of Biology and the Centre for Advance Research in Environmental Genomics, 30 Marie Curie, K1N 6N5 Ottawa, Canada
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21
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Robers MB, Binkowski BF, Cong M, Zimprich C, Corona C, McDougall M, Otto G, Eggers CT, Hartnett J, Machleidt T, Fan F, Wood KV. A luminescent assay for real-time measurements of receptor endocytosis in living cells. Anal Biochem 2015; 489:1-8. [PMID: 26278171 DOI: 10.1016/j.ab.2015.08.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 07/28/2015] [Accepted: 08/05/2015] [Indexed: 01/14/2023]
Abstract
Ligand-mediated endocytosis is a key autoregulatory mechanism governing the duration and intensity of signals emanating from cell surface receptors. Due to the mechanistic complexity of endocytosis and its emerging relevance in disease, simple methods capable of tracking this dynamic process in cells have become increasingly desirable. We have developed a bioluminescent reporter technology for real-time analysis of ligand-mediated receptor endocytosis using genetic fusions of NanoLuc luciferase with various G-protein-coupled receptors (GPCRs). This method is compatible with standard microplate formats, which should decrease work flows for high-throughput screens. This article also describes the application of this technology to endocytosis of epidermal growth factor receptor (EGFR), demonstrating potential applicability of the method beyond GPCRs.
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Affiliation(s)
| | | | - Mei Cong
- Promega Corporation, Fitchburg, WI 53711, USA
| | | | | | | | - George Otto
- Promega Corporation, Fitchburg, WI 53711, USA
| | | | | | | | - Frank Fan
- Promega Corporation, Fitchburg, WI 53711, USA
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22
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Ul-Haq Z, Saeed M, Halim SA, Khan W. 3D structure prediction of human β1-adrenergic receptor via threading-based homology modeling for implications in structure-based drug designing. PLoS One 2015; 10:e0122223. [PMID: 25860348 PMCID: PMC4393300 DOI: 10.1371/journal.pone.0122223] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 02/19/2015] [Indexed: 11/24/2022] Open
Abstract
Dilated cardiomyopathy is a disease of left ventricular dysfunction accompanied by impairment of the β1-adrenergic receptor (β1-AR) signal cascade. The disturbed β1-AR function may be based on an elevated sympathetic tone observed in patients with heart failure. Prolonged adrenergic stimulation may induce metabolic and electrophysiological disturbances in the myocardium, resulting in tachyarrhythmia that leads to the development of heart failure in human and sudden death. Hence, β1-AR is considered as a promising drug target but attempts to develop effective and specific drug against this tempting pharmaceutical target is slowed down due to the lack of 3D structure of Homo sapiens β1-AR (hsβADR1). This study encompasses elucidation of 3D structural and physicochemical properties of hsβADR1 via threading-based homology modeling. Furthermore, the docking performance of several docking programs including Surflex-Dock, FRED, and GOLD were validated by re-docking and cross-docking experiments. GOLD and Surflex-Dock performed best in re-docking and cross docking experiments, respectively. Consequently, Surflex-Dock was used to predict the binding modes of four hsβADR1 agonists. This study provides clear understanding of hsβADR1 structure and its binding mechanism, thus help in providing the remedial solutions of cardiovascular, effective treatment of asthma and other diseases caused by malfunctioning of the target protein.
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Affiliation(s)
- Zaheer Ul-Haq
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
| | - Maria Saeed
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
| | - Sobia Ahsan Halim
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Waqasuddin Khan
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
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Mörl K, Beck-Sickinger AG. Intracellular Trafficking of Neuropeptide Y Receptors. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 132:73-96. [PMID: 26055055 DOI: 10.1016/bs.pmbts.2015.02.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The multireceptor multiligand system of neuropeptide Y receptors and their ligands is involved in the regulation of a multitude of physiological and pathophysiological processes. Specific expression patterns, ligand-binding modes, and signaling properties contribute to the complex network regulating distinct cellular responses. Intracellular trafficking processes are important key steps that are regulated in context with accessory proteins. These proteins exert their influence by interacting directly or indirectly with the receptors, causing modification of the receptors, or operating as scaffolds for the assembly of larger signaling complexes. On the intracellular receptor faces, sequence-specific motifs have been identified that play an important role in this process. Interestingly, it is also possible to influence the receptor internalization by modification of the peptide ligand.
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Affiliation(s)
- Karin Mörl
- Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Leipzig, Germany.
| | - Annette G Beck-Sickinger
- Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Leipzig, Germany
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24
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Weathington JM, Hamki A, Cooke BM. Sex- and region-specific pubertal maturation of the corticotropin-releasing factor receptor system in the rat. J Comp Neurol 2014; 522:1284-98. [PMID: 24115088 DOI: 10.1002/cne.23475] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Revised: 09/16/2013] [Accepted: 09/18/2013] [Indexed: 12/27/2022]
Abstract
One of the most reliable findings in psychiatry is in the incidence of anxiety and depression. Beginning at puberty, women develop mood disorders twice as often as men. Because corticotropin-releasing factor (CRF) receptors are implicated, we compared CRF receptor binding in pre- and postpubertal rats. In each brain area, CRF receptor binding was sexually dimorphic, but no two areas were alike in the way the sexes differed. In the nucleus accumbens and olfactory tubercle, CRF1 binding was initially the same in juveniles, but became greater in adult females. In piriform cortex, CRF1 binding increased in females and decreased in males, again becoming sexually dimorphic. CRF1 binding in the anterior cingulate was greater in females than in males at both ages. In CA3, CRF1 binding was greater in males before puberty but decreased during puberty, abolishing the sex difference. CRF2 binding in the posterior bed nucleus of the stria terminalis was greater in males irrespective of age. In contrast, in each of three subdivisions of the lateral septum, females had greater CRF2 binding than males as juveniles, or, as juveniles and as adults. CRF2 binding in the ventromedial hypothalamus was the same in juveniles, but binding levels increased in males, leading to an adult sex difference. Thus, eight CRF receptor-expressing areas displayed eight distinct sex differences. These results show that sex differences pervade the CRF receptor system in juvenile and adult rats, and the mechanisms that control them are likely to be sex-, region-, and subtype-specific.
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Affiliation(s)
- Jill M Weathington
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, 30303
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25
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May V, Clason TA, Buttolph TR, Girard BM, Parsons RL. Calcium influx, but not intracellular calcium release, supports PACAP-mediated ERK activation in HEK PAC1 receptor cells. J Mol Neurosci 2014; 54:342-50. [PMID: 24723666 PMCID: PMC4194181 DOI: 10.1007/s12031-014-0300-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 03/28/2014] [Indexed: 01/10/2023]
Abstract
In HEK cells expressing GFP-tagged PAC1Hop1 receptors, PACAP augments ERK phosphorylation through two parallel pathways: one through PACAP/PAC1 receptor internalization/endosome MEK/ERK signaling and the other through PLC/DAG/PKC activation. We examined whether elevation of intracellular calcium ([Ca(2+)]i) was required for either of the PACAP/PAC1 receptor-mediated ERK activation mechanisms. The PACAP (25 nM)-induced elevation of [Ca(2+)]i was greater with cells maintained in Ca(2+)-containing than in Ca(2+)-deficient solution, suggesting that both calcium release from internal stores and calcium influx contributed to the rise in [Ca(2+)]i. A thapsigargin-induced increase in [Ca(2+)]i also was greater with calcium in the external solution. OAG, the cell permeable analogue of DAG, increased [Ca(2+)]i, but only in Ca(2+)-containing solution. Decreasing external calcium or depleting internal calcium stores did not block PACAP-induced PAC1 receptor internalization. Omission of calcium from the external solution, but not thapsigargin pretreatment, significantly blunted PACAP-stimulated ERK phosphorylation. The PKC inhibitor BimI decreased PACAP-mediated ERK activation in both Ca(2+)-containing or Ca(2+)-deficient solutions. In contrast, following Pitstop 2 pretreatment to block endocytic mechanisms, PACAP activated ERK only when calcium was present in the external solution. We conclude that the endosome signaling pathway is largely calcium-independent whereas calcium influx appears necessary for the PLC/DAG/PKC component of PACAP-induced ERK activation.
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Affiliation(s)
- Victor May
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, VT, 05405, USA
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26
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Brailoiu GC, Deliu E, Marcu J, Hoffman NE, Console-Bram L, Zhao P, Madesh M, Abood ME, Brailoiu E. Differential activation of intracellular versus plasmalemmal CB2 cannabinoid receptors. Biochemistry 2014; 53:4990-9. [PMID: 25033246 PMCID: PMC4144709 DOI: 10.1021/bi500632a] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
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The therapeutic and psychoactive
properties of cannabinoids have
long been recognized. The type 2 receptor for cannabinoids (CB2) has emerged as an important therapeutic target in several
pathologies, as it mediates beneficial effects of cannabinoids while
having little if any psychotropic activity. Difficulties associated
with the development of CB2-based therapeutic agents have
been related to its intricate pharmacology, including the species
specificity and functional selectivity of the CB2-initiated
responses. We postulated that a plasmalemmal or subcellular location
of the receptor may contribute to the differential signaling pathways
initiated by its activation. To differentiate between these two, we
used extracellular and intracellular administration of CB2 ligands and concurrent calcium imaging in CB2-expressing
U2OS cells. We found that extracellular administration of anandamide
was ineffective, whereas 2-arachidonoyl glycerol (2-AG) and WIN55,212-2
triggered delayed, CB2-dependent Ca2+ responses
that were Gq protein-mediated. When microinjected, all agonists elicited
fast, transient, and dose-dependent elevations in intracellular Ca2+ concentration upon activation of Gq-coupled CB2 receptors. The CB2 dependency was confirmed by the sensitivity
to AM630, a selective CB2 antagonist, and by the unresponsiveness
of untransfected U2OS cells to 2-AG, anandamide, or WIN55,212-2. Moreover,
we provide functional and morphological evidence that CB2 receptors are localized at the endolysosomes, while their activation
releases Ca2+ from inositol 1,4,5-trisphosphate-sensitive-
and acidic-like Ca2+ stores. Our results support the functionality
of intracellular CB2 receptors and their ability to couple
to Gq and elicit Ca2+ signaling. These findings add further
complexity to CB2 receptor pharmacology and argue for careful
consideration of receptor localization in the development of CB2-based therapeutic agents.
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Affiliation(s)
- G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Thomas Jefferson University School of Pharmacy , Philadelphia, Pennsylvania 19107, United States
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Development and evaluation of small peptidomimetic ligands to protease-activated receptor-2 (PAR2) through the use of lipid tethering. PLoS One 2014; 9:e99140. [PMID: 24927179 PMCID: PMC4057235 DOI: 10.1371/journal.pone.0099140] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 05/09/2014] [Indexed: 02/05/2023] Open
Abstract
Protease-activated receptor-2 (PAR2) is a G-Protein Coupled Receptor (GPCR) activated by proteolytic cleavage to expose an attached, tethered ligand (SLIGRL). We evaluated the ability for lipid-tethered-peptidomimetics to activate PAR2 with in vitro physiological and Ca2+ signaling assays to determine minimal components necessary for potent, specific and full PAR2 activation. A known PAR2 activating compound containing a hexadecyl (Hdc) lipid via three polyethylene glycol (PEG) linkers (2at-LIGRL-PEG3-Hdc) provided a potent agonist starting point (physiological EC50 = 1.4 nM; 95% CI: 1.2-2.3 nM). In a set of truncated analogs, 2at-LIGR-PEG3-Hdc retained potency (EC50 = 2.1 nM; 1.3-3.4 nM) with improved selectivity for PAR2 over Mas1 related G-protein coupled receptor type C11, a GPCR that can be activated by the PAR2 peptide agonist, SLIGRL-NH2. 2at-LIG-PEG3-Hdc was the smallest full PAR2 agonist, albeit with a reduced EC50 (46 nM; 20-100 nM). 2at-LI-PEG3-Hdc retained specific activity for PAR2 with reduced EC50 (310 nM; 260-360 nM) but displayed partial PAR2 activation in both physiological and Ca2+ signaling assays. Further truncation (2at-L-PEG3-Hdc and 2at-PEG3-Hdc) eliminated in vitro activity. When used in vivo, full and partial PAR2 in vitro agonists evoked mechanical hypersensitivity at a 15 pmole dose while 2at-L-PEG3-Hdc lacked efficacy. Minimum peptidomimetic PAR2 agonists were developed with known heterocycle substitutes for Ser1 (isoxazole or aminothiazoyl) and cyclohexylalanine (Cha) as a substitute for Leu2. Both heterocycle-tetrapeptide and heterocycle-dipeptides displayed PAR2 specificity, however, only the heterocycle-tetrapeptides displayed full PAR2 agonism. Using the lipid-tethered-peptidomimetic approach we have developed novel structure activity relationships for PAR2 that allows for selective probing of PAR2 function across a broad range of physiological systems.
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Ferrie AM, Wang C, Deng H, Fang Y. A label-free optical biosensor with microfluidics identifies an intracellular signalling wave mediated through the β(2)-adrenergic receptor. Integr Biol (Camb) 2014; 5:1253-61. [PMID: 23989552 DOI: 10.1039/c3ib40112j] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The canonical model of G protein-coupled receptor (GPCR) signalling states that it is solely initiated at the cell surface. In recent years, a handful of evidence has started emerging from high-resolution molecular assays that the internalized receptors can mediate the third wave of signalling, besides G protein- and β-arrestin-mediated signalling both initiating at the cell surface. However, little is known about the functional consequences of distinct waves of GPCR signalling, in particular, at the whole cell system level. We here report the development of label-free biosensor antagonist reverse assays and their use to differentiate the signalling waves of an endogenous β2-adrenergic receptor (β2-AR) in A431 cells. Results showed that the persistent agonist treatment activated the β2-ARs, leading to a long-term sustained dynamic mass redistribution (DMR) signal, a whole cell phenotypic response. Under the persistent treatment scheme in microplates, a panel of known β-blockers all dose-dependently and completely reversed the DMR signal of epinephrine at a relatively low dose (10 nM), except for sotalol which partially reversed the DMR. Under the perfusion conditions with microfluidics, the subsequent perfusion with sotalol only reversed the DMR induced by epinephrine or isoproterenol at 10 nM, but not at 10 μM. Furthermore, the degree of the DMR reversion by sotalol was found to be in an opposite relation with the duration of the initial agonist treatment. Together, these results suggest that the hydrophilic antagonist sotalol is constrained outside the cells throughout the assays, and the early signalling wave initiated at the cell surface dominates the DMR induced by epinephrine or isoproterenol at relatively low doses, while a secondary and late signalling wave is initiated once the receptors are internalized and contributes partially to the long-term sustainability of the DMR of epinephrine or isoproterenol at high doses.
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Affiliation(s)
- Ann M Ferrie
- Biochemical Technologies, Science and Technology Division, Corning Incorporated, Corning, NY 14831, USA.
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May V, Buttolph TR, Girard BM, Clason TA, Parsons RL. PACAP-induced ERK activation in HEK cells expressing PAC1 receptors involves both receptor internalization and PKC signaling. Am J Physiol Cell Physiol 2014; 306:C1068-79. [PMID: 24696141 DOI: 10.1152/ajpcell.00001.2014] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The pituitary adenylate cyclase-activating polypeptide (PACAP)-selective PAC1 receptor (Adcyap1r1) is a G protein-coupled receptor (GPCR) that activates adenylyl cyclase and PLC. Similar to many other GPCRs, our previous studies showed that the PAC1 receptor is internalized after ligand binding to form signaling endosomes, which recruit additional second messenger pathways. Using a human embryonic kidney (HEK 293) PAC1Hop1-EGFP receptor cell line, we have examined how different PAC1 receptor signaling mechanisms contribute to MEK/ERK activation. Unlike PAC1 receptor-stimulated adenylyl cyclase/cAMP production in the plasma membrane, PACAP-mediated ERK phosphorylation was partly dependent on receptor internalization, as determined by treatment with pharmacological inhibitors of endocytosis or temperature reduction, which also suppressed receptor internalization. Stimulation of cAMP generation by forskolin or exposure to the cell-permeable cAMP analogs 8-bromo-cAMP and dibutyryl cAMP had minimal effects on ERK phosphorylation in this system. The ability of reduced temperature (24°C) to consistently suppress ERK activation to a greater extent than the endocytosis inhibitors Pitstop 2 and dynasore indicated that other mechanisms, in addition to PAC1 internalization/endosome activation, were involved. Inhibition of PAC1 receptor-stimulated PLC/diacylglycerol/PKC signaling by bisindoylmaleimide I also attenuated ERK phosphorylation, and direct PKC activation with phorbol ester increased ERK phosphorylation in a temperature-dependent manner. Inhibition of PAC1 receptor endocytosis and PKC activation completely blocked PACAP-stimulated ERK activation. PACAP augmented phosphorylated ERK staining uniformly over the cytoplasm and nucleus, and PKC signaling facilitated nuclear phosphorylated ERK translocation. In sum, our results show that PACAP/PAC1 receptor endocytosis and PLC/diacylglycerol/PKC activation represent two complementary mechanisms contributing to PACAP-induced ERK activation.
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Affiliation(s)
- Victor May
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont
| | - Thomas R Buttolph
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont
| | - Beatrice M Girard
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont
| | - Todd A Clason
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont
| | - Rodney L Parsons
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont
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Tomanov K, Luschnig C, Bachmair A. Ubiquitin Lys 63 chains - second-most abundant, but poorly understood in plants. FRONTIERS IN PLANT SCIENCE 2014; 5:15. [PMID: 24550925 PMCID: PMC3907715 DOI: 10.3389/fpls.2014.00015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 01/14/2014] [Indexed: 05/20/2023]
Abstract
Covalent attachment of the small modifier ubiquitin to Lys ε-amino groups of proteins is surprisingly diverse. Once attached to a substrate, ubiquitin is itself frequently modified by ubiquitin, to form chains. All seven Lys residues of ubiquitin, as well as its N-terminal Met, can be ubiquitylated, implying cellular occurrence of different ubiquitin chain types. The available data suggest that the synthesis, recognition, and hydrolysis of different chain types are precisely regulated. This remarkable extent of control underlies a versatile cellular response to substrate ubiquitylation. In this review, we focus on roles of Lys63-linked ubiquitin chains in plants. Despite limited available knowledge, several recent findings illustrate the importance of these chains as signaling components in plants.
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Affiliation(s)
- Konstantin Tomanov
- Max F. Perutz Laboratories, Department of Biochemistry and Cell Biology, Center for Molecular Biology, University of ViennaVienna, Austria
| | - Christian Luschnig
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life SciencesVienna, Austria
| | - Andreas Bachmair
- Max F. Perutz Laboratories, Department of Biochemistry and Cell Biology, Center for Molecular Biology, University of ViennaVienna, Austria
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Geng FS, Abbas L, Baxendale S, Holdsworth CJ, Swanson AG, Slanchev K, Hammerschmidt M, Topczewski J, Whitfield TT. Semicircular canal morphogenesis in the zebrafish inner ear requires the function of gpr126 (lauscher), an adhesion class G protein-coupled receptor gene. Development 2013; 140:4362-74. [PMID: 24067352 PMCID: PMC4007713 DOI: 10.1242/dev.098061] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Morphogenesis of the semicircular canal ducts in the vertebrate inner ear is a dramatic example of epithelial remodelling in the embryo, and failure of normal canal development results in vestibular dysfunction. In zebrafish and Xenopus, semicircular canal ducts develop when projections of epithelium, driven by extracellular matrix production, push into the otic vesicle and fuse to form pillars. We show that in the zebrafish, extracellular matrix gene expression is high during projection outgrowth and then rapidly downregulated after fusion. Enzymatic disruption of hyaluronan in the projections leads to their collapse and a failure to form pillars: as a result, the ears swell. We have cloned a zebrafish mutant, lauscher (lau), identified by its swollen ear phenotype. The primary defect in the ear is abnormal projection outgrowth and a failure of fusion to form the semicircular canal pillars. Otic expression of extracellular matrix components is highly disrupted: several genes fail to become downregulated and remain expressed at abnormally high levels into late larval stages. The lau mutations disrupt gpr126, an adhesion class G protein-coupled receptor gene. Expression of gpr126 is similar to that of sox10, an ear and neural crest marker, and is partially dependent on sox10 activity. Fusion of canal projections and downregulation of otic versican expression in a hypomorphic lau allele can be restored by cAMP agonists. We propose that Gpr126 acts through a cAMP-mediated pathway to control the outgrowth and adhesion of canal projections in the zebrafish ear via the regulation of extracellular matrix gene expression.
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Affiliation(s)
- Fan-Suo Geng
- MRC Centre for Developmental and Biomedical Genetics and Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
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Yu J, Deliu E, Zhang XQ, Hoffman NE, Carter RL, Grisanti LA, Brailoiu GC, Madesh M, Cheung JY, Force T, Abood ME, Koch WJ, Tilley DG, Brailoiu E. Differential activation of cultured neonatal cardiomyocytes by plasmalemmal versus intracellular G protein-coupled receptor 55. J Biol Chem 2013; 288:22481-92. [PMID: 23814062 DOI: 10.1074/jbc.m113.456178] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The L-α-lysophosphatidylinositol (LPI)-sensitive receptor GPR55 is coupled to Ca(2+) signaling. Low levels of GPR55 expression in the heart have been reported. Similar to other G protein-coupled receptors involved in cardiac function, GPR55 may be expressed both at the sarcolemma and intracellularly. Thus, to explore the role of GPR55 in cardiomyocytes, we used calcium and voltage imaging and extracellular administration or intracellular microinjection of GPR55 ligands. We provide the first evidence that, in cultured neonatal ventricular myocytes, LPI triggers distinct signaling pathways via GPR55, depending on receptor localization. GPR55 activation at the sarcolemma elicits, on one hand, Ca(2+) entry via L-type Ca(2+) channels and, on the other, inositol 1,4,5-trisphosphate-dependent Ca(2+) release. The latter signal is further amplified by Ca(2+)-induced Ca(2+) release via ryanodine receptors. Conversely, activation of GPR55 at the membrane of intracellular organelles promotes Ca(2+) release from acidic-like Ca(2+) stores via the endolysosomal NAADP-sensitive two-pore channels. This response is similarly enhanced by Ca(2+)-induced Ca(2+) release via ryanodine receptors. Extracellularly applied LPI produces Ca(2+)-independent membrane depolarization, whereas the Ca(2+) signal induced by intracellular microinjection of LPI converges to hyperpolarization of the sarcolemma. Collectively, our findings point to GPR55 as a novel G protein-coupled receptor regulating cardiac function at two cellular sites. This work may serve as a platform for future studies exploring the potential of GPR55 as a therapeutic target in cardiac disorders.
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Affiliation(s)
- Justine Yu
- Center for Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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Klos A, Wende E, Wareham KJ, Monk PN. International Union of Basic and Clinical Pharmacology. [corrected]. LXXXVII. Complement peptide C5a, C4a, and C3a receptors. Pharmacol Rev 2013; 65:500-43. [PMID: 23383423 DOI: 10.1124/pr.111.005223] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The activation of the complement cascade, a cornerstone of the innate immune response, produces a number of small (74-77 amino acid) fragments, originally termed anaphylatoxins, that are potent chemoattractants and secretagogues that act on a wide variety of cell types. These fragments, C5a, C4a, and C3a, participate at all levels of the immune response and are also involved in other processes such as neural development and organ regeneration. Their primary function, however, is in inflammation, so they are important targets for the development of antiinflammatory therapies. Only three receptors for complement peptides have been found, but there are no satisfactory antagonists as yet, despite intensive investigation. In humans, there is a single receptor for C3a (C3a receptor), no known receptor for C4a, and two receptors for C5a (C5a₁ receptor and C5a₂ receptor). The most recently characterized receptor, the C5a₂ receptor (previously known as C5L2 or GPR77), has been regarded as a passive binding protein, but signaling activities are now ascribed to it, so we propose that it be formally identified as a receptor and be given a name to reflect this. Here, we describe the complex biology of the complement peptides, introduce a new suggested nomenclature, and review our current knowledge of receptor pharmacology.
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Affiliation(s)
- Andreas Klos
- Department for Medical Microbiology, Medical School Hannover, Hannover, Germany
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Palczewski K, Orban T. From atomic structures to neuronal functions of g protein-coupled receptors. Annu Rev Neurosci 2013; 36:139-64. [PMID: 23682660 DOI: 10.1146/annurev-neuro-062012-170313] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
G protein-coupled receptors (GPCRs) are essential mediators of signal transduction, neurotransmission, ion channel regulation, and other cellular events. GPCRs are activated by diverse stimuli, including light, enzymatic processing of their N-termini, and binding of proteins, peptides, or small molecules such as neurotransmitters. GPCR dysfunction caused by receptor mutations and environmental challenges contributes to many neurological diseases. Moreover, modern genetic technology has helped identify a rich array of mono- and multigenic defects in humans and animal models that connect such receptor dysfunction with disease affecting neuronal function. The visual system is especially suited to investigate GPCR structure and function because advanced imaging techniques permit structural studies of photoreceptor neurons at both macro and molecular levels that, together with biochemical and physiological assessment in animal models, provide a more complete understanding of GPCR signaling.
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Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965, USA.
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Pituitary adenylate cyclase 1 receptor internalization and endosomal signaling mediate the pituitary adenylate cyclase activating polypeptide-induced increase in guinea pig cardiac neuron excitability. J Neurosci 2013; 33:4614-22. [PMID: 23467377 DOI: 10.1523/jneurosci.4999-12.2013] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
After G-protein-coupled receptor activation and signaling at the plasma membrane, the receptor complex is often rapidly internalized via endocytic vesicles for trafficking into various intracellular compartments and pathways. The formation of signaling endosomes is recognized as a mechanism that produces sustained intracellular signals that may be distinct from those generated at the cell surface for cellular responses including growth, differentiation, and survival. Pituitary adenylate cyclase activating polypeptide (PACAP; Adcyap1) is a potent neurotransmitter/neurotrophic peptide and mediates its diverse cellular functions in part through internalization of its cognate G-protein-coupled PAC1 receptor (PAC1R; Adcyap1r1). In the present study, we examined whether PAC1R endocytosis participates in the regulation of neuronal excitability. Although PACAP increased excitability in 90% of guinea pig cardiac neurons, pretreatment with Pitstop 2 or dynasore to inhibit clathrin and dynamin I/II, respectively, suppressed the PACAP effect. Subsequent addition of inhibitor after the PACAP-induced increase in excitability developed gradually attenuated excitability with no changes in action potential properties. Likewise, the PACAP-induced increase in excitability was markedly decreased at ambient temperature. Receptor trafficking studies with GFP-PAC1 cell lines demonstrated the efficacy of Pitstop 2, dynasore, and low temperatures at suppressing PAC1R endocytosis. In contrast, brefeldin A pretreatments to disrupt Golgi vesicle trafficking did not blunt the PACAP effect, and PACAP/PAC1R signaling still increased neuronal cAMP production even with endocytic blockade. Our results demonstrate that PACAP/PAC1R complex endocytosis is a key step for the PACAP modulation of cardiac neuron excitability.
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36
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Daly K, Al-Rammahi M, Moran A, Marcello M, Ninomiya Y, Shirazi-Beechey SP. Sensing of amino acids by the gut-expressed taste receptor T1R1-T1R3 stimulates CCK secretion. Am J Physiol Gastrointest Liver Physiol 2013; 304. [PMID: 23203156 PMCID: PMC3566511 DOI: 10.1152/ajpgi.00074.2012] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
CCK is secreted by endocrine cells of the proximal intestine in response to dietary components, including amino acids. CCK plays a variety of roles in digestive processes, including inhibition of food intake, consistent with a role in satiety. In the lingual epithelium, the sensing of a broad spectrum of L-amino acids is accomplished by the heteromeric amino acid (umami) taste receptor (T1R1-T1R3). T1R1 and T1R3 subunits are also expressed in the intestine. A defining characteristic of umami sensing by T1R1-T1R3 is its potentiation by IMP or GMP. Furthermore, T1R1-T1R3 is not activated by Trp. We show here that, in response to L-amino acids (Phe, Leu, Glu, and Trp), but not D-amino acids, STC-1 enteroendocrine cells and mouse proximal small intestinal tissue explants secrete CCK and that IMP enhances Phe-, Leu-, and Glu-induced, but not Trp-induced, CCK secretion. Furthermore, small interfering RNA inhibition of T1R1 expression in STC-1 cells results in significant diminution of Phe-, Leu-, and Glu-stimulated, but not Trp-stimulated, CCK release. In STC-1 cells and mouse intestine, gurmarin inhibits Phe-, Leu-, and Glu-induced, but not Trp-stimulated, CCK secretion. In contrast, the Ca(2+)-sensing receptor antagonist NPS2143 inhibits Phe-stimulated CCK release partially and Trp-induced CCK secretion totally in mouse intestine. However, NPS2143 has no effect on Leu- or Glu-induced CCK secretion. Collectively, our data demonstrate that functional characteristics and cellular location of the gut-expressed T1R1-T1R3 support its role as a luminal sensor for Phe-, Leu-, and Glu-induced CCK secretion.
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Affiliation(s)
- Kristian Daly
- 1Epithelial Function and Development Group, Department of Functional and Comparative Genomics, University of Liverpool, Liverpool, United Kingdom;
| | - Miran Al-Rammahi
- 1Epithelial Function and Development Group, Department of Functional and Comparative Genomics, University of Liverpool, Liverpool, United Kingdom;
| | - Andrew Moran
- 1Epithelial Function and Development Group, Department of Functional and Comparative Genomics, University of Liverpool, Liverpool, United Kingdom;
| | - Marco Marcello
- 2Centre for Imaging, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom; and
| | - Yuzo Ninomiya
- 3Section of Oral Neuroscience, Graduate School of Dental Sciences, Kyushu University, Fukuoka, Japan
| | - Soraya P. Shirazi-Beechey
- 1Epithelial Function and Development Group, Department of Functional and Comparative Genomics, University of Liverpool, Liverpool, United Kingdom;
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Abstract
BACKGROUND Interaction of Schwann cells with axons triggers signal transduction that drives expression of Pou3f1 and Egr2 transcription factors, which in turn promote myelination. Signal transduction appears to be mediated, at least in part, by cyclic adenosine monophosphate (cAMP) because elevation of cAMP levels can stimulate myelination in the absence of axon contact. The mechanisms by which the myelinating signal is conveyed remain unclear. RESULTS By analyzing mutations that disrupt myelination in zebrafish, we learned that Dynein cytoplasmic 1 heavy chain 1 (Dync1h1), which functions as a motor for intracellular molecular trafficking, is required for peripheral myelination. In dync1h1 mutants, Schwann cell progenitors migrated to peripheral nerves but then failed to express Pou3f1 and Egr2 or make myelin membrane. Genetic mosaic experiments revealed that robust Myelin Basic Protein expression required Dync1h1 function within both Schwann cells and axons. Finally, treatment of dync1h1 mutants with a drug to elevate cAMP levels stimulated myelin gene expression. CONCLUSION Dync1h1 is required for retrograde transport in axons and mutations of Dync1h1 have been implicated in axon disease. Our data now provide evidence that Dync1h1 is also required for efficient myelination of peripheral axons by Schwann cells, perhaps by facilitating signal transduction necessary for myelination.
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Affiliation(s)
- Melissa M Langworthy
- Departments of Pediatrics and Cell and Developmental Biology, University of Colorado School of Medicine, MS 8108, Aurora, CO, 80045, USA
| | - Bruce Appel
- Departments of Pediatrics and Cell and Developmental Biology, University of Colorado School of Medicine, MS 8108, Aurora, CO, 80045, USA
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Dupakuntla M, Pathak B, Roy BS, Mahale SD. Extracellular loop 2 in the FSH receptor is crucial for ligand mediated receptor activation. Mol Cell Endocrinol 2012; 362:60-8. [PMID: 22641019 DOI: 10.1016/j.mce.2012.05.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 05/17/2012] [Accepted: 05/18/2012] [Indexed: 10/28/2022]
Abstract
The present study aims to determine the role of the specific residues of the extracellular loops (ELs) of the FSH receptor (FSHR) in hormone binding and receptor activation. By substituting the sequences of each of the ELs of human FSHR with those of the luteinizing hormone/choriogonadotropin receptor (LH/CGR), we generated three mutant constructs where the three ELs were individually replaced. A fourth construct had all the three substituted ELs. The receptor expression and hormone binding ability of the mutants were comparable to that of the wild type. Hormone-induced signaling and internalization were lower in the EL2 substitution mutant (EL2M). In this mutant, the EL2 of FSHR was substituted with the corresponding loop of LH/CGR. Interestingly, homology modeling revealed a change in the orientation of EL2 in the mutant receptor. Thus, disruption of EL2 affected overall receptor function, suggesting the role of FSHR specific residues of the loop in ligand mediated signaling.
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Affiliation(s)
- Madhavi Dupakuntla
- Division of Structural Biology, National Institute for Research in Reproductive Health (Indian Council of Medical Research), Parel, Mumbai 400 012, India
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Kamato D, Burch ML, Osman N, Zheng W, Little PJ. Therapeutic implications of endothelin and thrombin G-protein-coupled receptor transactivation of tyrosine and serine/threonine kinase cell surface receptors. J Pharm Pharmacol 2012; 65:465-73. [DOI: 10.1111/j.2042-7158.2012.01577.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Abstract
Objectives
This review discusses the latest developments in G protein coupled receptor (GPCR) signalling related to the transactivation of cell surface protein kinase receptors and the therapeutic implications.
Key findings
Multiple GPCRs have been known to transactivate protein tyrosine kinase receptors for almost two decades. More recently it has been discovered that GPCRs can also transactivate protein serine/threonine kinase receptors such as that for transforming growth factor (TGF)-β. Using the model of proteoglycan synthesis and glycosaminoglycan elongation in human vascular smooth muscle cells which is a component of an in vitro model of atherosclerosis, the dual tyrosine and serine/threonine kinase receptor transactivation pathways appear to account for all of the response to the agonists, endothelin and thrombin.
Summary
The broadening of the paradigm of GPCR receptor transactivation explains the broad range of activities of these receptors and also the efficacy of GPCR antagonists in cardiovascular therapeutics. Deciphering the mechanisms of transactivation with the aim of identifying a common therapeutic target remains the next challenge.
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Affiliation(s)
- Danielle Kamato
- Discipline of Pharmacy, School of Medical Sciences, Australia
- Diabetes Complications Group, Metabolism, Exercise and Disease Program, Health Innovations Research Institute, RMIT University, Melbourne, Australia
| | - Micah L Burch
- Diabetes Complications Group, Metabolism, Exercise and Disease Program, Health Innovations Research Institute, RMIT University, Melbourne, Australia
- Department of Medicine, Monash University School of Medicine (Central and Eastern Clinical School, Alfred Health), Prahran VIC, Australia
| | - Narin Osman
- Discipline of Pharmacy, School of Medical Sciences, Australia
- Diabetes Complications Group, Metabolism, Exercise and Disease Program, Health Innovations Research Institute, RMIT University, Melbourne, Australia
| | - Wenhua Zheng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Centre and School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China
| | - Peter J Little
- Discipline of Pharmacy, School of Medical Sciences, Australia
- Diabetes Complications Group, Metabolism, Exercise and Disease Program, Health Innovations Research Institute, RMIT University, Melbourne, Australia
- Department of Medicine, Monash University School of Medicine (Central and Eastern Clinical School, Alfred Health), Prahran VIC, Australia
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Shapiro MG, Frazier SJ, Lester HA. Unparalleled control of neural activity using orthogonal pharmacogenetics. ACS Chem Neurosci 2012; 3:619-29. [PMID: 22896806 DOI: 10.1021/cn300053q] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 06/01/2012] [Indexed: 11/28/2022] Open
Abstract
Studying the functional architecture of the brain requires technologies to precisely measure and perturb the activity of specific neural cells and circuits in live animals. Substantial progress has been made in recent years to develop and apply such tools. In particular, technologies that provide precise control of activity in genetically defined populations of neurons have enabled the study of causal relationships between and among neural circuit elements and behavioral outputs. Here, we review an important subset of such technologies, in which neurons are genetically engineered to respond to specific chemical ligands that have no interfering pharmacological effect in the central nervous system. A rapidly expanding set of these "orthogonal pharmacogenetic" tools provides a unique combination of genetic specificity, functional diversity, spatiotemporal precision, and potential for multiplexing. We review the main classes of orthogonal pharmacogenetic technologies, including neuroreceptors to control neuronal excitability, systems to control gene transcription and translation, and general constructs to control protein-protein interactions, enzymatic function, and protein stability. We describe the key performance characteristics informing the use of these technologies in the brain, and potential directions for improvement and expansion of the orthogonal pharmacogenetics toolkit to enable more sophisticated systems neuroscience.
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Affiliation(s)
- Mikhail G. Shapiro
- Miller Research Institute, Department
of Bioengineering, and Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California
94720, United States
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Muniz VS, Weller PF, Neves JS. Eosinophil crystalloid granules: structure, function, and beyond. J Leukoc Biol 2012; 92:281-8. [PMID: 22672875 DOI: 10.1189/jlb.0212067] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Eosinophils are granulocytes associated with host defense against parasitic helminths with allergic conditions and more recently, with immunoregulatory responses. Eosinophils are distinguished from leukocytes by their dominant population of cytoplasmic crystalloid (also termed secretory, specific, or secondary) granules that contain robust stores of diverse, preformed cationic proteins. Here, we provide an update on our knowledge about the unique and complex structure of human eosinophil crystalloid granules. We discuss their significance as rich sites of a variety of receptors and review our own recent research findings and those of others that highlight discoveries concerning the function of intracellular receptors and their potential implications in cell signaling. Special focus is provided on how eosinophils might use these intracellular receptors as mechanisms to secrete, selectively and rapidly, cytokines or chemokines and enable cell-free extracellular eosinophil granules to function as independent secretory structures. Potential roles of cell-free eosinophil granules as immune players in the absence of intact eosinophils will also be discussed.
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Affiliation(s)
- Valdirene S Muniz
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, UFRJ, Rio de Janeiro, Brazil
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42
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Antoni FA. New paradigms in cAMP signalling. Mol Cell Endocrinol 2012; 353:3-9. [PMID: 22085559 DOI: 10.1016/j.mce.2011.10.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 10/24/2011] [Accepted: 10/29/2011] [Indexed: 12/16/2022]
Abstract
Signalling through adenosine 3'5' monophosphate (cAMP) is known to be important in virtually every cell. The mapping of the human genome over the past two decades has revealed an unexpected complexity of cAMP signalling, which is shared from insects to mammals. A more recent technical advance is the ability to monitor intracellular cAMP levels at subcellular spatial resolution within the time-domains of fast biochemical reactions. Thus, new light has been shed on old paradigms, some of which turn out to be multiple new ones. The novel aspects of cAMP signalling are highlighted here: (1) agonist induced plasticity - showing how the repertory of cAMP signalling genes supports homeostatic adaptation; (2) sustained cAMP signalling after endocytosis; (3) pre-assembled receptor-Gs-adenylyl cyclase complexes. Finally, a hypothetical model of propagating neuronal cAMP signals travelling form dendrites to the cell body is presented.
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Affiliation(s)
- Ferenc A Antoni
- Division of Preclinical Research, EGIS PLC, Bökényföldi út 116, 1165 Budapest, Hungary.
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Xu TR, Ward RJ, Pediani JD, Milligan G. Intramolecular fluorescence resonance energy transfer (FRET) sensors of the orexin OX1 and OX2 receptors identify slow kinetics of agonist activation. J Biol Chem 2012; 287:14937-49. [PMID: 22389503 DOI: 10.1074/jbc.m111.334300] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Intramolecular fluorescence resonance energy transfer (FRET) sensors able to detect changes in distance or orientation between the 3rd intracellular loop and C-terminal tail of the human orexin OX(1) and OX(2) G protein-coupled receptors following binding of agonist ligands were produced and expressed stably. These were directed to the plasma membrane and, despite the substantial sequence alterations introduced, in each case were able to elevate [Ca(2+)](i), promote phosphorylation of the ERK1/2 MAP kinases and become internalized effectively upon addition of the native orexin peptides. Detailed characterization of the OX(1) sensor demonstrated that it was activated with rank order of potency orexin A > orexin B > orexin A 16-33, that it bound antagonist ligands with affinity similar to the wild-type receptor, and that mutation of a single residue, D203A, greatly reduced the binding and function of orexin A but not antagonist ligands. Addition of orexin A to individual cells expressing an OX(1) sensor resulted in a time- and concentration-dependent reduction in FRET signal consistent with mass-action and potency/affinity estimates for the peptide. Compared with the response kinetics of a muscarinic M(3) acetylcholine receptor sensor upon addition of agonist, response of the OX(1) and OX(2) sensors to orexin A was slow, consistent with a multistep binding and activation process. Such sensors provide means to assess the kinetics of receptor activation and how this may be altered by mutation and sequence variation of the receptors.
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Affiliation(s)
- Tian-Rui Xu
- Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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Xin Z, Shenhua X, Hanzhou M, Linhui G, Chihong Z, Xianglin L. Identification and chromosomal localizations of signal transduction genes associated with human ovarian cancer metastasis. Med Oncol 2012; 29:2932-6. [PMID: 22311261 DOI: 10.1007/s12032-012-0164-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 01/07/2012] [Indexed: 11/28/2022]
Abstract
Gene chip technology can be used to identify and localize signal transduction genes associated with metastasis. We used the human genome U133A gene chip to detect differences in gene expression profiles among high (H) and low (L) metastatic human ovarian cancer cell lines (HO-8910PM, HO-8910), and normal ovarian tissues (C), to identify metastasis-associated signal transduction genes and determine their chromosomal localizations. A total of 37 signal transduction genes showed more than twofold differences in expression levels between the H and L metastatic ovarian cancer cell lines; of these, 21 genes were up-regulated [signal log ratio (SLR)≥1], and 16 genes were down-regulated (SLR≤-1). Most genes were located on chromosome 1 (7 genes, 18.9%), followed by chromosome 8 (5 genes, 13.5%), then chromosomes 6, 11, and 17 (3 genes each, 8.1%). A total of 21 of the differentially expressed genes (56.7%) were localized on the short arm of the chromosome (q). The disruption of signal transduction gene expression may be an important factor associated with ovarian cancer metastasis. The affected signal transduction genes were localized to chromosomes 1, 8, 6, 11, and 17.
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Affiliation(s)
- Zhu Xin
- Zhejiang Cancer Research Institute, Zhejiang Cancer Hospital, Guangji Road 38, Hangzhou, 310022, Zhejiang Province, China
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Huang Y, Cavanaugh A, Breitwieser GE. Regulation of stability and trafficking of calcium-sensing receptors by pharmacologic chaperones. ADVANCES IN PHARMACOLOGY 2012; 62:143-73. [PMID: 21907909 DOI: 10.1016/b978-0-12-385952-5.00007-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Gain- or loss-of-function mutations and polymorphisms of the calcium-sensing receptor (CaSR) cause Ca(2+) handling diseases. Altered expression and/or signaling of wild-type CaSR can also contribute to pathology. Recent studies have demonstrated that a significant proportion of mutations cause altered targeting and/or trafficking of CaSR to the plasma membrane. Pharmacological approaches to rescue of CaSR function include treatment with allosteric modulators, which potentiate the effects of the orthosteric agonist Ca(2+). Dissection of the mechanism(s) contributing to allosteric agonist-mediated rescue of loss-of-function CaSR mutants has demonstrated pharmacologic chaperone actions coincident with CaSR biosynthesis. The distinctive responses to the allosteric agonist (NPS R-568), which promotes CaSR stability, and the allosteric antagonist (NPS 2143), which promotes CaSR degradation, have led to a model for a conformational checkpoint during CaSR biosynthesis. The conformational checkpoint would "tune" CaSR biosynthesis to cellular signaling state. Navigation of a distinct checkpoint for endoplasmic release can also be augmented by pharmacologic chaperones. The diverse, post-endoplasmic reticulum quality control site(s) for pharmacologic chaperone modulation of CaSR stability and trafficking redefines the role(s) of allosteric modulators in regulation of overall GPCR function.
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Affiliation(s)
- Ying Huang
- Cancer Drug Research Laboratory, McGill University, Royal Victoria Hospital, Montreal, Quebec, Canada
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Schadich E, Mason D, Sin F. Co-expressed peJK genes of lobster (Jasus edwardsii). AUST J ZOOL 2012. [DOI: 10.1071/zo11105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Previous studies have shown that the two novel genes of southern rock lobster (Jasus edwardsii) named peJK2 and peJK3 are implicated in eyestalk hormonal regulation of the lobster moult cycle. Northern blot, in situ hybridisation studies and sequence analyses showed that their putative products might be transmembrane proteins associated with cell signal transduction of hormonal signals in the eyestalk during the intermoult phase of the moult cycle. The aim of this study was to analyse coexpression of peJK genes in different J. edwardsii tissues. Using reverse transcriptase–polymerase chain reaction (RT-PCR), the expression of peJK genes was analysed in seven different tissues (eyestalk, brain, epidermis, hepatopancreas, gill, muscle and heart) of an intermoult lobster. During RT-PCR analysis, a novel sequence was isolated, and was named peJK4. It shares 88% and 86% sequence identity with peJK2 and peJK3 respectively. The peJK2 and peJK4 genes are expressed in all tested tissues. Sequence analyses of the predicted peJK2 and peJK4 proteins revealed two common signal transduction motifs, transmembrane helices and protein kinase C. These results showed that the peJK genes of J. edwardsii are a complex group of genes and possibly involved in different signal transduction pathways.
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Christiansen SH. Regulation of the galanin system in the brainstem and hypothalamus by electroconvulsive stimulation in mice. Neuropeptides 2011; 45:337-41. [PMID: 21820174 DOI: 10.1016/j.npep.2011.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 06/27/2011] [Accepted: 07/12/2011] [Indexed: 12/01/2022]
Abstract
Induction of seizures by electroconvulsive stimulation (ECS) is amongst the most efficacious treatments for major depression. However, the working mechanism by which ECS exerts its antidepressant effects remains elusive. The galanin system is regulated by ECS in seizure-prone brain regions and has been shown to modulate depression-like behaviour. To further explore its potential role in the antidepressant effects of ECS the galanin system was investigated by in situ hybridisation and [(125)I]-galanin receptor binding during repeated ECS in the locus coeruleus, dorsal raphe and discrete nuclei of the hypothalamus. Adult mice were treated with ECS once daily for 14 consecutive days, a paradigm previously shown to exert antidepressant-like effects. Significant increases in galanin transcription were found in the locus coeruleus and dorsomedial nuclei of the hypothalamus. In addition, GalR2 mRNA levels in the ventro- and dorsomedial nuclei of the hypothalamus were upregulated whereas no GalR1 mRNA upregulation was observed. [(125)I]-galanin receptor binding was downregulated in the ventromedial nuclei of the hypothalamus and dorsal raphe. These data show that the galanin system is regulated by repeated ECS in brain regions involved in monoaminergic neurotransmission and stress modulation thus indicating a possible role of the galanin system in the therapeutic effects of ECS.
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Affiliation(s)
- S H Christiansen
- Psychiatric Centre Copenhagen, Rigshospitalet O-6102, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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Edwards HV, Christian F, Baillie GS. cAMP: novel concepts in compartmentalised signalling. Semin Cell Dev Biol 2011; 23:181-90. [PMID: 21930230 DOI: 10.1016/j.semcdb.2011.09.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 09/08/2011] [Indexed: 12/12/2022]
Abstract
Cyclic adenosine 3,'5'-monophosphate (cAMP) is the archetypal second messenger produced at the membrane by adenylyl cyclase following activation of many different G protein-coupled receptor (GPCR) types. Although discovered over fifty years ago, the notion that cAMP responses were compartmentalised was born in the 1980s. Since then, modern molecular techniques have facilitated visualisation of cellular cAMP dynamics in real time and helped us to understand how a single, ubiquitous second messenger can direct receptor-specific functions in cells. The aim of this review is to highlight emerging ideas in the cAMP field that are currently developing the concept of compartmentalised cAMP signalling systems.
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Affiliation(s)
- Helen V Edwards
- Institute of Neuroscience and Molecular Pharmacology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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Wang L, Du C, Lv J, Wei W, Cui Y, Xie X. Antiasthmatic drugs targeting the cysteinyl leukotriene receptor 1 alleviate central nervous system inflammatory cell infiltration and pathogenesis of experimental autoimmune encephalomyelitis. THE JOURNAL OF IMMUNOLOGY 2011; 187:2336-45. [PMID: 21804021 DOI: 10.4049/jimmunol.1100333] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cysteinyl leukotrienes (CysLTs) are potent proinflammatory mediators and are considered to play a key role in inflammatory diseases such as asthma. Antagonists targeting the receptor of CysLTs (CysLT1) are currently used as antiasthmatic drugs. CysLTs have also been implicated in other inflammatory reactions. In this study, we report that in experimental autoimmune encephalomyelitis animals, CysLT1 is upregulated in immune tissue and the spinal cord, and CysLT levels in the blood and cerebrospinal fluid are also higher than in normal mice. Two clinically used antiasthma drugs, montelukast and zafirlukast, both targeting CysLT1, effectively block the CNS infiltration of inflammatory cells and thus reduce the incidence, peak severity, and cumulative clinical scores. Further study indicated that CysLT1 signaling does not affect the differentiation of pathogenic T helper cells. It might affect the pathogenesis of experimental autoimmune encephalomyelitis by increasing the secretion of IL-17 from myelin oligodendrocyte glycoprotein-specific T cells, increasing the permeability of the blood-brain barrier and inducing chemotaxis of T cells. These effects can be blocked by CysLT1 antagonists. Our findings indicate that the antiasthmatic drugs against CysLT1 can also be used to treat multiple sclerosis.
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Affiliation(s)
- Liefeng Wang
- Laboratory of Receptor-Based BioMedicine, School of Life Sciences and Technology, Shanghai Key Laboratory of Signaling and Disease Research, Tongji University, Shanghai 200092, China
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Abstract
Dopamine is an important regulator of systemic blood pressure via multiple mechanisms. It affects fluid and electrolyte balance by its actions on renal hemodynamics and epithelial ion and water transport and by regulation of hormones and humoral agents. The kidney synthesizes dopamine from circulating or filtered L-DOPA independently from innervation. The major determinants of the renal tubular synthesis/release of dopamine are probably sodium intake and intracellular sodium. Dopamine exerts its actions via two families of cell surface receptors, D1-like receptors comprising D1R and D5R, and D2-like receptors comprising D2R, D3R, and D4R, and by interactions with other G protein-coupled receptors. D1-like receptors are linked to vasodilation, while the effect of D2-like receptors on the vasculature is variable and probably dependent upon the state of nerve activity. Dopamine secreted into the tubular lumen acts mainly via D1-like receptors in an autocrine/paracrine manner to regulate ion transport in the proximal and distal nephron. These effects are mediated mainly by tubular mechanisms and augmented by hemodynamic mechanisms. The natriuretic effect of D1-like receptors is caused by inhibition of ion transport in the apical and basolateral membranes. D2-like receptors participate in the inhibition of ion transport during conditions of euvolemia and moderate volume expansion. Dopamine also controls ion transport and blood pressure by regulating the production of reactive oxygen species and the inflammatory response. Essential hypertension is associated with abnormalities in dopamine production, receptor number, and/or posttranslational modification.
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Affiliation(s)
- Ines Armando
- Children’s National Medical Center—Center for Molecular Physiology Research, Washington, District of Columbia
| | - Van Anthony M. Villar
- Children’s National Medical Center—Center for Molecular Physiology Research, Washington, District of Columbia
| | - Pedro A. Jose
- Children’s National Medical Center—Center for Molecular Physiology Research, Washington, District of Columbia
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