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Campana C, Iyer AM, Ferone D, Gatto F, Hofland LJ. Somatostatin receptors and the associated intracellular machinery: the two sides of the coin. J Endocrinol 2024; 260:e230298. [PMID: 38224333 DOI: 10.1530/joe-23-0298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 12/20/2023] [Indexed: 01/16/2024]
Abstract
Somatostatin receptors (SSTs) are widely expressed in pituitary tumors and neuroendocrine neoplasms (NENs) of different origins, i.e. the gastrointestinal tract and the thorax (lungs and thymus), thus representing a well-established target for medical treatment with SST ligands (SRLs). However, the response to SRLs is highly heterogeneous between tumors. Two main factors can contribute to this variability: (i) the differential SST expression among tumor types and (ii) the differential expression/modulation of the SST-related intracellular machinery. In this literature review, we provide an overview of available data on the variable expression of SSTs in pituitary tumors and NENs, together with the resulting clinical implications. Moreover, we aim to describe the complex intracellular machinery involved in SST signaling and trafficking. Particularly, we will focus on β-arrestins and describe their role in receptor internalization and recycling, as well as the various functions of these scaffold molecules in tumor pathogenesis and progression. This review highlights the interplay between membrane receptors and intracellular machinery, together with its role in determining the clinical behavior of the tumor and the response to treatment in patients with pituitary tumors or NENs.
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Affiliation(s)
- Claudia Campana
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, Rotterdam, The Netherlands
- Endocrinology Unit, Department of Internal Medicine and Medical Specialties, School of Medical and Pharmaceutical Sciences, University of Genova, Genova, Italy
| | - Anand M Iyer
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Diego Ferone
- Endocrinology Unit, Department of Internal Medicine and Medical Specialties, School of Medical and Pharmaceutical Sciences, University of Genova, Genova, Italy
- Endocrinology Unit, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Federico Gatto
- Endocrinology Unit, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Leo J Hofland
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, Rotterdam, The Netherlands
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Yadav MK, Maharana J, Yadav R, Saha S, Sarma P, Soni C, Singh V, Saha S, Ganguly M, Li XX, Mohapatra S, Mishra S, Khant HA, Chami M, Woodruff TM, Banerjee R, Shukla AK, Gati C. Molecular basis of anaphylatoxin binding, activation, and signaling bias at complement receptors. Cell 2023; 186:4956-4973.e21. [PMID: 37852260 PMCID: PMC7615941 DOI: 10.1016/j.cell.2023.09.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 07/19/2023] [Accepted: 09/20/2023] [Indexed: 10/20/2023]
Abstract
The complement system is a critical part of our innate immune response, and the terminal products of this cascade, anaphylatoxins C3a and C5a, exert their physiological and pathophysiological responses primarily via two GPCRs, C3aR and C5aR1. However, the molecular mechanism of ligand recognition, activation, and signaling bias of these receptors remains mostly elusive. Here, we present nine cryo-EM structures of C3aR and C5aR1 activated by their natural and synthetic agonists, which reveal distinct binding pocket topologies of complement anaphylatoxins and provide key insights into receptor activation and transducer coupling. We also uncover the structural basis of a naturally occurring mechanism to dampen the inflammatory response of C5a via proteolytic cleavage of the terminal arginine and the G-protein signaling bias elicited by a peptide agonist of C3aR identified here. In summary, our study elucidates the innerworkings of the complement anaphylatoxin receptors and should facilitate structure-guided drug discovery to target these receptors in a spectrum of disorders.
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Affiliation(s)
- Manish K Yadav
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Jagannath Maharana
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Ravi Yadav
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA; The Bridge Institute, Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA, USA
| | - Shirsha Saha
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Parishmita Sarma
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Chahat Soni
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Vinay Singh
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Sayantan Saha
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Manisankar Ganguly
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Xaria X Li
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Samanwita Mohapatra
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Sudha Mishra
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Htet A Khant
- USC Center of Excellence for Nano-Imaging, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Mohamed Chami
- BioEM Lab, Biozentrum, Universität Basel, Basel, Switzerland
| | - Trent M Woodruff
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ramanuj Banerjee
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India.
| | - Arun K Shukla
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India.
| | - Cornelius Gati
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA; The Bridge Institute, Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA, USA; Department of Chemistry, Department of Quantitative and Computational Biology, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA, USA.
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Abstract
CONTEXT Thyroid eye disease (TED) is a complex autoimmune disease process. Orbital fibroblasts represent the central orbital immune target. Involvement of the TSH receptor (TSHR) in TED is not fully understood. IGF-I receptor (IGF-IR) is overexpressed in several cell types in TED, including fibrocytes and orbital fibroblasts. IGF-IR may form a physical and functional complex with TSHR. OBJECTIVE Review literature relevant to autoantibody generation in TED and whether these induce orbital fibroblast responses directly through TSHR, IGF-IR, or both. EVIDENCE IGF-IR has traditionally been considered a typical tyrosine kinase receptor in which tyrosine residues become phosphorylated following IGF-I binding. Evidence has emerged that IGF-IR possesses kinase-independent activities and can be considered a functional receptor tyrosine kinase/G-protein-coupled receptor hybrid, using the G-protein receptor kinase/β-arrestin system. Teprotumumab, a monoclonal IGF-IR antibody, effectively reduces TED disease activity, proptosis, and diplopia. In addition, the drug attenuates in vitro actions of both IGF-I and TSH in fibrocytes and orbital fibroblasts, including induction of proinflammatory cytokines by TSH and TED IgGs. CONCLUSIONS Although teprotumumab has been proven effective and relatively safe in the treatment of TED, many questions remain pertaining to IGF-IR, its relationship with TSHR, and how the drug might be disrupting these receptor protein/protein interactions. Here, we propose 4 possible IGF-IR activation models that could underlie clinical responses to teprotumumab observed in patients with TED. Teprotumumab is associated with several adverse events, including hyperglycemia and hearing abnormalities. Underpinning mechanisms of these are being investigated. Patients undergoing treatment with drug must be monitored for these and managed with best medical practices.
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Affiliation(s)
- Leonard Girnita
- Department of Oncology and Pathology, BioClinicum, Karolinska Institutet and Karolinska University Hospital, 17164 Stockholm, Sweden
| | - Terry J Smith
- Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, MI 48105, USA
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Joseph A M J L Janssen
- Correspondence: Joseph A.M.J.L. Janssen, MD, PhD, Erasmus Medical Centre, Erasmus MC, Molewaterplein 40, 3015 GD Rotterdam, Netherlands.
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Willis Fox O, Preston RJS. Molecular basis of protease-activated receptor 1 signaling diversity. J Thromb Haemost 2020; 18:6-16. [PMID: 31549766 DOI: 10.1111/jth.14643] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/13/2019] [Accepted: 09/17/2019] [Indexed: 12/13/2022]
Abstract
Protease-activated receptors (PARs) are a family of highly conserved G protein-coupled receptors (GPCRs) that respond to extracellular proteases via a unique proteolysis-dependent activation mechanism. Protease-activated receptor 1 (PAR1) was the first identified member of the receptor family and plays important roles in hemostasis, inflammation and malignancy. The biology underlying PAR1 signaling by its canonical agonist thrombin is well characterized; however, definition of the mechanistic basis of PAR1 signaling by other proteases, including matrix metalloproteases, activated protein C, plasmin, and activated factors VII and X, remains incompletely understood. In this review, we discuss emerging insights into the molecular bases for "biased" PAR1 signaling, including atypical PAR1 proteolysis, PAR1 heterodimer and coreceptor interactions, PAR1 translocation on the membrane surface, and interactions with different G-proteins and β-arrestins upon receptor activation. Moreover, we consider how these new insights into PAR1 signaling have acted to spur development of novel PAR1-targeted therapeutics that act to inhibit, redirect, or fine-tune PAR1 signaling output to treat cardiovascular and inflammatory disease. Finally, we discuss some of the key unanswered questions relating to PAR1 biology, in particular how differences in PAR1 proteolysis, signaling intermediate coupling, and engagement with coreceptors and GPCRs combine to mediate the diversity of identified PAR1 signaling outputs.
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Affiliation(s)
- Orla Willis Fox
- Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
- Department of Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Roger J S Preston
- Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
- Department of Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
- National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin, Ireland
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Ma Z, Yu YR, Badea CT, Kovacs JJ, Xiong X, Comhair S, Piantadosi CA, Rajagopal S. Vascular Endothelial Growth Factor Receptor 3 Regulates Endothelial Function Through β-Arrestin 1. Circulation 2019; 139:1629-1642. [PMID: 30586762 DOI: 10.1161/circulationaha.118.034961] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Receptor signaling is central to vascular endothelial function and is dysregulated in vascular diseases such as atherosclerosis and pulmonary arterial hypertension (PAH). Signaling pathways involved in endothelial function include vascular endothelial growth factor receptors (VEGFRs) and G protein-coupled receptors, which classically activate distinct intracellular signaling pathways and responses. The mechanisms that regulate these signaling pathways have not been fully elucidated and it is unclear what nodes for cross talk exist between these diverse signaling pathways. For example, multifunctional β-arrestin (ARRB) adapter proteins are best known as regulators of G protein-coupled receptor signaling, but their role at other receptors and their physiological importance in the setting of vascular disease are unclear. METHODS We used a combination of human samples from PAH, human microvascular endothelial cells from lung, and Arrb knockout mice to determine the role of ARRB1 in endothelial VEGFR3 signaling. In addition, a number of biochemical analyses were performed to determine the interaction between ARRB1 and VEGFR3, signaling mediators downstream of VEGFR3, and the internalization of VEGFR3. RESULTS Expression of ARRB1 and VEGFR3 was reduced in human PAH, and the deletion of Arrb1 in mice exposed to hypoxia led to worse PAH with a loss of VEGFR3 signaling. Knockdown of ARRB1 inhibited VEGF-C-induced endothelial cell proliferation, migration, and tube formation, along with reduced VEGFR3, Akt, and endothelial nitric oxide synthase phosphorylation. This regulation was mediated by direct ARRB1 binding to the VEGFR3 kinase domain and resulted in decreased VEGFR3 internalization. CONCLUSIONS Our results demonstrate a novel role for ARRB1 in VEGFR regulation and suggest a mechanism for cross talk between G protein-coupled receptors and VEGFRs in PAH. These findings also suggest that strategies to promote ARRB1-mediated VEGFR3 signaling could be useful in the treatment of pulmonary hypertension and other vascular disease.
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Affiliation(s)
- Zhiyuan Ma
- Division of Cardiology (Z.M., X.X., S.R.), Duke University Medical Center, Durham, NC
| | - Yen-Rei Yu
- Division of Pulmonary and Critical Care (Y.-R.Y., C.A.P.), Duke University Medical Center, Durham, NC
| | - Cristian T Badea
- Department of Radiology (C.T.B.), Duke University Medical Center, Durham, NC
| | - Jeffrey J Kovacs
- Department of Medicine (J.J.K.), Duke University Medical Center, Durham, NC
| | - Xinyu Xiong
- Division of Cardiology (Z.M., X.X., S.R.), Duke University Medical Center, Durham, NC
| | - Suzy Comhair
- Lerner Research Institute, Cleveland Clinic, OH (S.C.). The current address for Dr Kovacs is MD Anderson Cancer Center Institute for Applied Cancer Science and Center for Co-Clinical Trials, Houston, TX
| | - Claude A Piantadosi
- Division of Pulmonary and Critical Care (Y.-R.Y., C.A.P.), Duke University Medical Center, Durham, NC
| | - Sudarshan Rajagopal
- Division of Cardiology (Z.M., X.X., S.R.), Duke University Medical Center, Durham, NC.,Department of Biochemistry (S.R.), Duke University Medical Center, Durham, NC
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