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Scharf MM, Humphrys LJ, Berndt S, Di Pizio A, Lehmann J, Liebscher I, Nicoli A, Niv MY, Peri L, Schihada H, Schulte G. The dark sides of the GPCR tree - research progress on understudied GPCRs. Br J Pharmacol 2024. [PMID: 38339984 DOI: 10.1111/bph.16325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/24/2023] [Accepted: 01/08/2024] [Indexed: 02/12/2024] Open
Abstract
A large portion of the human GPCRome is still in the dark and understudied, consisting even of entire subfamilies of GPCRs such as odorant receptors, class A and C orphans, adhesion GPCRs, Frizzleds and taste receptors. However, it is undeniable that these GPCRs bring an untapped therapeutic potential that should be explored further. Open questions on these GPCRs span diverse topics such as deorphanisation, the development of tool compounds and tools for studying these GPCRs, as well as understanding basic signalling mechanisms. This review gives an overview of the current state of knowledge for each of the diverse subfamilies of understudied receptors regarding their physiological relevance, molecular mechanisms, endogenous ligands and pharmacological tools. Furthermore, it identifies some of the largest knowledge gaps that should be addressed in the foreseeable future and lists some general strategies that might be helpful in this process.
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Affiliation(s)
- Magdalena M Scharf
- Karolinska Institutet, Dept. Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Stockholm, Sweden
| | - Laura J Humphrys
- Institute of Pharmacy, University of Regensburg, Regensburg, Germany
| | - Sandra Berndt
- Rudolf Schönheimer Institute for Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Antonella Di Pizio
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
- Chemoinformatics and Protein Modelling, Department of Molecular Life Science, School of Life Science, Technical University of Munich, Freising, Germany
| | - Juliane Lehmann
- Rudolf Schönheimer Institute for Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Ines Liebscher
- Rudolf Schönheimer Institute for Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Alessandro Nicoli
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
- Chemoinformatics and Protein Modelling, Department of Molecular Life Science, School of Life Science, Technical University of Munich, Freising, Germany
| | - Masha Y Niv
- The Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Lior Peri
- The Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Hannes Schihada
- Institute of Pharmaceutical Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Gunnar Schulte
- Karolinska Institutet, Dept. Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Stockholm, Sweden
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Cholecystokinin (CCK) and its receptors (CCK1R and CCK2R) in chickens: functional analysis and tissue expression. Poult Sci 2022; 102:102273. [PMID: 36436379 PMCID: PMC9706633 DOI: 10.1016/j.psj.2022.102273] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 09/25/2022] [Accepted: 10/15/2022] [Indexed: 11/06/2022] Open
Abstract
Cholecystokinin (CCK) is widely distributed in the gastrointestinal tract and central nervous system, regulating a range of physiological functions by activating its receptors (CCK1R and CCK2R). Compared to those in mammals, the CCK gene and its receptors have already been cloned in various birds, such as chickens. However, knowledge regarding their functionality and tissue expression is limited. In this study, we examined the expression of CCK and its 2 receptors in chicken tissues. In addition, the functionality of the 2 receptors was investigated. Using 3 cell-based luciferase reporter systems and western blots, we demonstrated that chicken (c-) CCK1R could be potently activated by cCCK-8S but not cCCK-4, whereas cCCK2R could be activated by cCCK-8S and cCCK-4 with similar efficiency. Using RNA-sequencing, we revealed that cCCK is abundantly expressed in the testis, ileum, and several brain regions (cerebrum, midbrain, cerebellum, hindbrain, and hypothalamus). The abundant expression of CCK in the hypothalamus was further supported by immunofluorescence. In addition, cCCK1R is highly expressed in the pancreas and moderately expressed in various intestinal regions (ileum, cecum, and rectum) and the pituitary gland, whereas cCCK2R expression is primarily restricted to the brain. Our data reveal the differential specificities of CCK receptors for various CCK peptides. In combination with the differential tissue distribution of CCK and its receptors, the present study helps to understanding the physiological functions of CCK/CCKRs in birds.
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Strutt B, Szlapinski S, Gnaneswaran T, Donegan S, Hill J, Bennett J, Hill DJ. Ontology of the apelinergic system in mouse pancreas during pregnancy and relationship with β-cell mass. Sci Rep 2021; 11:15475. [PMID: 34326390 PMCID: PMC8322410 DOI: 10.1038/s41598-021-94725-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 07/15/2021] [Indexed: 02/07/2023] Open
Abstract
The apelin receptor (Aplnr) and its ligands, Apelin and Apela, contribute to metabolic control. The insulin resistance associated with pregnancy is accommodated by an expansion of pancreatic β-cell mass (BCM) and increased insulin secretion, involving the proliferation of insulin-expressing, glucose transporter 2-low (Ins+Glut2LO) progenitor cells. We examined changes in the apelinergic system during normal mouse pregnancy and in pregnancies complicated by glucose intolerance with reduced BCM. Expression of Aplnr, Apelin and Apela was quantified in Ins+Glut2LO cells isolated from mouse pancreata and found to be significantly higher than in mature β-cells by DNA microarray and qPCR. Apelin was localized to most β-cells by immunohistochemistry although Aplnr was predominantly associated with Ins+Glut2LO cells. Aplnr-staining cells increased three- to four-fold during pregnancy being maximal at gestational days (GD) 9-12 but were significantly reduced in glucose intolerant mice. Apelin-13 increased β-cell proliferation in isolated mouse islets and INS1E cells, but not glucose-stimulated insulin secretion. Glucose intolerant pregnant mice had significantly elevated serum Apelin levels at GD 9 associated with an increased presence of placental IL-6. Placental expression of the apelinergic axis remained unaltered, however. Results show that the apelinergic system is highly expressed in pancreatic β-cell progenitors and may contribute to β-cell proliferation in pregnancy.
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Affiliation(s)
- Brenda Strutt
- Lawson Health Research Institute, St Joseph Health Care, 268 Grosvenor St, London, ON, N6A 4V2, Canada
| | - Sandra Szlapinski
- Lawson Health Research Institute, St Joseph Health Care, 268 Grosvenor St, London, ON, N6A 4V2, Canada
- Department of Physiology and Pharmacology, Western University, London, ON, N6A 3K7, Canada
| | - Thineesha Gnaneswaran
- Department of Physiology and Pharmacology, Western University, London, ON, N6A 3K7, Canada
| | - Sarah Donegan
- Department of Physiology and Pharmacology, Western University, London, ON, N6A 3K7, Canada
| | - Jessica Hill
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, EX2 5DW, UK
| | - Jamie Bennett
- Lawson Health Research Institute, St Joseph Health Care, 268 Grosvenor St, London, ON, N6A 4V2, Canada
- Life Sciences Program, School of Interdisciplinary Science, McMaster University, Hamilton, ON, L8S 4LD, Canada
| | - David J Hill
- Lawson Health Research Institute, St Joseph Health Care, 268 Grosvenor St, London, ON, N6A 4V2, Canada.
- Department of Physiology and Pharmacology, Western University, London, ON, N6A 3K7, Canada.
- Departments of Medicine and Paediatrics, Western University, London, ON, N6A 3K7, Canada.
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Molecular Cloning and Functional Characterization of Three 5-HT Receptor Genes ( HTR1B, HTR1E, and HTR1F) in Chickens. Genes (Basel) 2021; 12:genes12060891. [PMID: 34207786 PMCID: PMC8230051 DOI: 10.3390/genes12060891] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/29/2021] [Accepted: 06/02/2021] [Indexed: 02/06/2023] Open
Abstract
The serotonin (5-hydroxytryptamine, 5-HT) signaling system is involved in a variety of physiological functions, including the control of cognition, reward, learning, memory, and vasoconstriction in vertebrates. Contrary to the extensive studies in the mammalian system, little is known about the molecular characteristics of the avian serotonin signaling network. In this study, we cloned and characterized the full-length cDNA of three serotonin receptor genes (HTR1B, HTR1E and HTR1F) in chicken pituitaries. Synteny analyses indicated that HTR1B, HTR1E and HTR1F were highly conserved across vertebrates. Cell-based luciferase reporter assays showed that the three chicken HTRs were functional, capable of binding their natural ligands (5-HT) or selective agonists (CP94253, BRL54443, and LY344864) and inhibiting intracellular cAMP production in a dose-dependent manner. Moreover, activation of these receptors could stimulate the MAPK/ERK signaling cascade. Quantitative real-time PCR analyses revealed that HTR1B, HTR1E and HTR1F were primarily expressed in various brain regions and the pituitary. In cultured chicken pituitary cells, we found that LY344864 could significantly inhibit the secretion of PRL stimulated by vasoactive intestinal peptide (VIP) or forskolin, revealing that HTR1F might be involved in the release of prolactin in chicken. Our findings provide insights into the molecular mechanism and facilitate a better understanding of the serotonergic modulation via HTR1B, HTR1E and HTR1F in avian species.
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Wang C, Xiong M, Yang C, Yang D, Zheng J, Fan Y, Wang S, Gai Y, Lan X, Chen H, Zheng L, Huang K. PEGylated and Acylated Elabela Analogues Show Enhanced Receptor Binding, Prolonged Stability, and Remedy of Acute Kidney Injury. J Med Chem 2020; 63:16028-16042. [PMID: 33290073 DOI: 10.1021/acs.jmedchem.0c01913] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Acute kidney injury (AKI), mostly caused by renal ischemia-reperfusion (I/R) injury and nephrotoxins, is characterized by rapid deterioration in renal-functions without effective drug treatment available. Through activation of a G protein-coupled receptor APJ, a furin-cleaved fragment of Elabela (ELA[22-32], E11), an endogenous APJ ligand, protects against renal I/R injury. However, the poor plasma stability and relatively weak APJ-binding ability of E11 limit its application. To address these issues, we rationally designed and synthesized a set of E11 analogues modified by palmitic acid (Pal) or polyethylene glycol; improved plasma stability and APJ-binding capacity of these analogues were achieved. In cultured renal tubular cells, these analogues protected against hypoxia-reperfusion or cisplatin-caused injury. For renal I/R-injured mice, these analogues showed improved reno-protective effects than E11; notably, Pal-E11 showed therapeutic effects at 24 h post I/R injury. These results present ELA analogues as potential therapeutic options in managing AKI.
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Affiliation(s)
- Chao Wang
- School of Pharmacy, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430030, China
| | - Mingrui Xiong
- School of Pharmacy, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430030, China
| | - Chen Yang
- School of Pharmacy, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430030, China
| | - Dong Yang
- School of Pharmacy, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430030, China
| | - Jiaojiao Zheng
- School of Pharmacy, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430030, China
| | - Yu Fan
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Shun Wang
- Department of Blood Transfusion, Wuhan Hospital of Traditional and Western Medicine, Wuhan 430022, China
| | - Yongkang Gai
- Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430022, China.,Hubei Key Laboratory of Molecular Imaging, Wuhan 430022, China
| | - Xiaoli Lan
- Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430022, China.,Hubei Key Laboratory of Molecular Imaging, Wuhan 430022, China
| | - Hong Chen
- School of Pharmacy, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430030, China
| | - Ling Zheng
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Kun Huang
- School of Pharmacy, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430030, China
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Wang X, Liu X, Song Z, Shen X, Lu S, Ling Y, Kuang H. Emerging roles of APLN and APELA in the physiology and pathology of the female reproductive system. PeerJ 2020; 8:e10245. [PMID: 33240613 PMCID: PMC7666558 DOI: 10.7717/peerj.10245] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/05/2020] [Indexed: 12/20/2022] Open
Abstract
APLN, APELA and their common receptor APLNR (composing the apelinergic axis) have been described in various species with extensive body distribution and multiple physiological functions. Recent studies have witnessed emerging intracellular cascades triggered by APLN and APELA which play crucial roles in female reproductive organs, including hypothalamus-pituitary-gonadal axis, ovary, oviduct, uterus and placenta. However, a comprehensive summary of APLN and APELA roles in physiology and pathology of female reproductive system has not been reported to date. In this review, we aim to concentrate on the general characteristics of APLN and APELA, as well as their specific physiological roles in female reproductive system. Meanwhile, the pathological contexts of apelinergic axis dysregulation in the obstetrics and gynecology are also summarized here, suggesting its potential prospect as a diagnostic biomarker and/or therapeutic intervention in the polycystic ovary syndrome, ovarian cancer, preeclampsia and gestational diabetes mellitus.
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Affiliation(s)
- Xueying Wang
- Department of Physiology, Basic Medical College, Nanchang University, Nanchang, China.,Department of Clinical Medicine, School of Queen Mary, Nanchang University, Nanchang, China
| | - Xiaofei Liu
- Department of Physiology, Basic Medical College, Nanchang University, Nanchang, China.,Department of Clinical Medicine, School of Queen Mary, Nanchang University, Nanchang, China
| | - Zifan Song
- Department of Physiology, Basic Medical College, Nanchang University, Nanchang, China
| | - Xin Shen
- Department of Physiology, Basic Medical College, Nanchang University, Nanchang, China
| | - Siying Lu
- Department of Physiology, Basic Medical College, Nanchang University, Nanchang, China
| | - Yan Ling
- Department of Obstetrics and Gynecology, Jiangxi provincial People's Hospital affiliated Nanchang University, Nanchang, China
| | - Haibin Kuang
- Department of Physiology, Basic Medical College, Nanchang University, Nanchang, China.,Jiangxi Provincial Key Laboratory of Reproductive Physiology and Pathology, Medical Experimental Teaching Center of Nanchang University, Nanchang, China
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Elabela and Apelin actions in healthy and pathological pregnancies. Cytokine Growth Factor Rev 2019; 46:45-53. [PMID: 30910349 DOI: 10.1016/j.cytogfr.2019.03.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 03/12/2019] [Indexed: 12/18/2022]
Abstract
Pregnancy is a dynamic and precisely organized process during which one or more baby develops. Embryonic development relies on the formation of the placenta, allowing nutrient and oxygen exchange between the mother and the fetus. Dysfunction of placental formation lead to pregnancy disorders such as preeclampsia (PE) with serious deleterious consequences for fetal and maternal health. Identifying factors involved in fetoplacental homeostasis could inform better diagnostic and therapeutic strategies for these pathological pregnancies. Here, we summarize actions of elabela, apelin and their common receptor APJ in the fetoplacental unit. Studies indicate that elabela is crucial for embryo cardiovascular system formation and early placental development, while apelin acts in mid/late gestation to modulate fetal angiogenesis and energy homeostasis. Most of these findings, drawn from animal models, indicate a key role of elabela/apelin-APJ system in the fetoplacental unit. This review also provides an overview of clinical studies investigating elabela/apelin-APJ system in pathological complicated pregnancies such as PE and gestational diabetes mellitus (GDM). While elabela-deficient mice display all the features of PE, current clinical studies show no difference in circulating elabela levels between PE and control patients which does not support a role in PE development. Conversely, apelin levels are increased during PE, but the use of apelin as an early PE marker remains to be fully investigated.
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Podgórska M, Pietraszek-Gremplewicz K, Nowak D. Apelin Effects Migration and Invasion Abilities of Colon Cancer Cells. Cells 2018; 7:cells7080113. [PMID: 30127323 PMCID: PMC6115746 DOI: 10.3390/cells7080113] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 08/16/2018] [Accepted: 08/16/2018] [Indexed: 12/19/2022] Open
Abstract
Colon cancer is one of the most common cancer types. Its positive correlation with general obesity has led to increasing amounts of research focusing on the role of adipokines in colon cancer development. Apelin is a peptide released by adipose tissue that could affect many cellular processes connected with carcinogenesis. In this study, we examined the role of apelin in the motility regulation of colon cancer cells. We showed that the effect of four different apelin peptides increased the ability of cancer cells to migrate and invade examined cells trough influencing migratory protrusions formation and actin cytoskeleton rearrangement. Additionally, using confocal microscopy, we noticed that apelin stimulated the proteolytic activity of cancer cells, especially increasing the level of membrane-type 1 matrix metalloprotease. Taken together, apelin increased the movement of colon cancer cells through several possible mechanisms. Moreover, better understanding the process through which apelin regulates cancer development is still necessary to the creation of novel anti-cancer therapy.
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Affiliation(s)
- Marta Podgórska
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wroclaw, Poland.
| | | | - Dorota Nowak
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wroclaw, Poland.
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Zhang J, Zhou Y, Wu C, Wan Y, Fang C, Li J, Fang W, Yi R, Zhu G, Li J, Wang Y. Characterization of the Apelin/Elabela Receptors (APLNR) in Chickens, Turtles, and Zebrafish: Identification of a Novel Apelin-Specific Receptor in Teleosts. Front Endocrinol (Lausanne) 2018; 9:756. [PMID: 30631305 PMCID: PMC6315173 DOI: 10.3389/fendo.2018.00756] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 11/29/2018] [Indexed: 12/22/2022] Open
Abstract
Apelin receptor(s) (APLNR) are suggested to mediate the actions of apelin and Elabela (ELA) peptides in many physiological processes, including cardiovascular development and food intake in vertebrates. However, the functionality of APLNR has not been examined in most vertebrate groups. Here, we characterized two APLNRs APLNR1, APLNR2) in chickens and red-eared sliders, and three APLNRs in zebrafish (APLNR2a, APLNR2b, APLNR3a), which are homologous to human APLNR. Using luciferase-reporter assays or Western blot, we demonstrated that in chickens, APLNR1 (not APLNR2) expressed in HEK293 cells was potently activated by chicken apelin-36 and ELA-32 and coupled to Gi-cAMP and MAPK/ERK signaling pathways, indicating a crucial role of APLNR1 in mediating apelin/ELA actions; in red-eared sliders, APLNR2 (not APLNR1) was potently activated by apelin-36/ELA-32, suggesting that APLNR2 may mediate apelin/ELA actions; in zebrafish, both APLNR2a and APLNR2b were potently activated by apelin-36/ELA-32 and coupled to Gi-cAMP signaling pathway, as previously proposed, whereas the novel APLNR3a was specifically and potently activated by apelin. Similarly, an apelin-specific receptor (APLNR3b) sharing 57% sequence identity with zebrafish APLNR3a was identified in Nile tilapia. Collectively, our data facilitates the uncovering of the roles of APLNR signaling in different vertebrate groups and suggests a key functional switch between APLNR1 and APLNR2/3 in mediating the actions of ELA and apelin during vertebrate evolution.
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