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Hu S, Wang D, Liu W, Wang Y, Chen J, Cai X. Apelin receptor dimer: Classification, future prospects, and pathophysiological perspectives. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167257. [PMID: 38795836 DOI: 10.1016/j.bbadis.2024.167257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/25/2024] [Accepted: 05/17/2024] [Indexed: 05/28/2024]
Abstract
Apelin receptor (APJ), a member of the class A family of G protein-coupled receptor (GPCR), plays a crucial role in regulating cardiovascular and central nervous systems function. APJ influences the onset and progression of various diseases such as hypertension, atherosclerosis, and cerebral stroke, making it an important target for drug development. Our preliminary findings indicate that APJ can form homodimers, heterodimers, or even higher-order oligomers, which participate in different signaling pathways and have distinct functions compared with monomers. APJ homodimers can serve as neuroprotectors against, and provide new pharmaceutical targets for vascular dementia (VD). This review article aims to summarize the structural characteristics of APJ dimers and their roles in physiology and pathology, as well as explore their potential pharmacological applications.
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Affiliation(s)
- Shujuan Hu
- School of Basic Medical Sciences, Shandong Second Medical University, Weifang, Shandong 261042, PR China
| | - Dexiu Wang
- School of Basic Medical Sciences, Shandong Second Medical University, Weifang, Shandong 261042, PR China
| | - Wenkai Liu
- School of Basic Medical Sciences, Shandong Second Medical University, Weifang, Shandong 261042, PR China
| | - Yixiang Wang
- School of Clinical Medicine, Shandong Second Medical University, Weifang, Shandong 261042, PR China
| | - Jing Chen
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, PR China; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK.
| | - Xin Cai
- School of Basic Medical Sciences, Shandong Second Medical University, Weifang, Shandong 261042, PR China.
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McCormick RA, Ralbovsky NM, Gilbraith W, Smith JP, Booksh KS. Analyzing atomic force microscopy images of virus-like particles by expectation-maximization. NPJ Vaccines 2024; 9:112. [PMID: 38902288 PMCID: PMC11190231 DOI: 10.1038/s41541-024-00871-7] [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: 05/05/2023] [Accepted: 03/28/2024] [Indexed: 06/22/2024] Open
Abstract
Analysis of virus-like particles (VLPs) is an essential task in optimizing their implementation as vaccine antigens for virus-initiated diseases. Interrogating VLP collections for elasticity by probing with a rigid atomic force microscopy (AFM) tip is a potential method for determining VLP morphological changes. During VLP morphological change, it is not expected that all VLPs would be in the same state. This leads to the open question of whether VLPs may change in a continuous or stepwise fashion. For continuous change, the statistical distribution of observed VLP properties would be expected as a single distribution, while stepwise change would lead to a multimodal distribution of properties. This study presents the application of a Gaussian mixture model (GMM), fit by the Expectation-Maximization (EM) algorithm, to identify different states of VLP morphological change observed by AFM imaging.
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Affiliation(s)
- Rachel A McCormick
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Nicole M Ralbovsky
- Analytical Research & Development, MRL, Merck & Co., Inc, West Point, PA, 19486, USA
| | - William Gilbraith
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Joseph P Smith
- Process Research & Development, MRL, Merck & Co., Inc, West Point, PA, 19486, USA.
| | - Karl S Booksh
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
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Mao Q, Wang L, Xue D, Lin X, Sun F, Xu P, Chen J, Li W, Li X, Yan F, Hu C. Imaging GPCR Dimerization in Living Cells with Cucurbit[7]uril and Hemicyanine as a "Turn-On" Fluorescence Probe. Anal Chem 2024; 96:2022-2031. [PMID: 38259189 DOI: 10.1021/acs.analchem.3c04493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Although multiple forms of dimers have been described for GPCR, their dynamics and function are still controversially discussed field. Fluorescence microscopy allows GPCR to be imaged within their native context; however, a key challenge is to site-specifically incorporate reporter moieties that can produce high-quality signals upon formation of GPCR dimers. To this end, we propose a supramolecular sensor approach to detect agonist-induced dimer formation of μ-opioid receptors (μORs) at the surface of intact cells. With the macrocyclic host cucurbit[7]uril and its guest hemicyanine dye tethered to aptamer strands directed against the histidine residues, the sensing module is assembled by host-guest complexation once the histidine-tagged μORs dimerize and bring the discrete supramolecular units into close proximity. With the enhanced sensitivity attributed by the "turn-on" fluorescence emission and high specificity afforded by the intermolecular recognition, in situ visualization of dynamic GPCR dimerization was realized with high precision, thereby validating the supramolecular sensing entity as a sophisticated and versatile strategy to investigate GPCR dimers, which represent an obvious therapeutic target.
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Affiliation(s)
- Qiuxiang Mao
- Department of Pharmaceutical Engineering, China Pharmaceutical University, No. 24 Tongjiaxiang Road, Nanjing 210009, China
| | - Lancheng Wang
- Department of Pharmaceutical Engineering, China Pharmaceutical University, No. 24 Tongjiaxiang Road, Nanjing 210009, China
| | - Dandan Xue
- Department of Pharmacy, China Pharmaceutical University, No. 24 Tongjiaxiang Road, Nanjing 210009, China
| | - Xiaoxuan Lin
- Department of Pharmacy, China Pharmaceutical University, No. 24 Tongjiaxiang Road, Nanjing 210009, China
| | - Fang Sun
- Department of Pharmaceutical Engineering, China Pharmaceutical University, No. 24 Tongjiaxiang Road, Nanjing 210009, China
| | - Pengcheng Xu
- Department of Pharmaceutical Engineering, China Pharmaceutical University, No. 24 Tongjiaxiang Road, Nanjing 210009, China
| | - Jieru Chen
- Department of Pharmaceutical Engineering, China Pharmaceutical University, No. 24 Tongjiaxiang Road, Nanjing 210009, China
| | - Wenying Li
- Department of Pharmacy, China Pharmaceutical University, No. 24 Tongjiaxiang Road, Nanjing 210009, China
| | - Xiuchen Li
- Department of Pharmacy, China Pharmaceutical University, No. 24 Tongjiaxiang Road, Nanjing 210009, China
| | - Fang Yan
- Department of Pharmacy, China Pharmaceutical University, No. 24 Tongjiaxiang Road, Nanjing 210009, China
| | - Chi Hu
- Department of Pharmaceutical Engineering, China Pharmaceutical University, No. 24 Tongjiaxiang Road, Nanjing 210009, China
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Sadee W. Ligand-Free Signaling of G-Protein-Coupled Receptors: Physiology, Pharmacology, and Genetics. Molecules 2023; 28:6375. [PMID: 37687205 PMCID: PMC10489045 DOI: 10.3390/molecules28176375] [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: 07/29/2023] [Revised: 08/28/2023] [Accepted: 08/30/2023] [Indexed: 09/10/2023] Open
Abstract
G-protein-coupled receptors (GPCRs) are ubiquitous sensors and regulators of cellular functions. Each GPCR exists in complex aggregates with multiple resting and active conformations. Designed to detect weak stimuli, GPCRs can also activate spontaneously, resulting in basal ligand-free signaling. Agonists trigger a cascade of events leading to an activated agonist-receptor G-protein complex with high agonist affinity. However, the ensuing signaling process can further remodel the receptor complex to reduce agonist affinity, causing rapid ligand dissociation. The acutely activated ligand-free receptor can continue signaling, as proposed for rhodopsin and μ opioid receptors, resulting in robust receptor activation at low agonist occupancy with enhanced agonist potency. Continued receptor stimulation can further modify the receptor complex, regulating sustained ligand-free signaling-proposed to play a role in opioid dependence. Basal, acutely agonist-triggered, and sustained elevated ligand-free signaling could each have distinct functions, reflecting multi-state conformations of GPCRs. This review addresses basal and stimulus-activated ligand-free signaling, its regulation, genetic factors, and pharmacological implications, focusing on opioid and serotonin receptors, and the growth hormone secretagogue receptor (GHSR). The hypothesis is proposed that ligand-free signaling of 5-HT2A receptors mediate therapeutic effects of psychedelic drugs. Research avenues are suggested to close the gaps in our knowledge of ligand-free GPCR signaling.
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Affiliation(s)
- Wolfgang Sadee
- Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA;
- Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158, USA
- Aether Therapeutics Inc., Austin, TX 78756, USA
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Platelet P2Y 1 receptor exhibits constitutive G protein signaling and β-arrestin 2 recruitment. BMC Biol 2023; 21:14. [PMID: 36721118 PMCID: PMC9890698 DOI: 10.1186/s12915-023-01528-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 01/25/2023] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Purinergic P2Y1 and P2Y12 receptors (P2Y1-R and P2Y12-R) are G protein-coupled receptors (GPCR) activated by adenosine diphosphate (ADP) to mediate platelet activation, thereby playing a pivotal role in hemostasis and thrombosis. While P2Y12-R is the major target of antiplatelet drugs, no P2Y1-R antagonist has yet been developed for clinical use. However, accumulating data suggest that P2Y1-R inhibition would ensure efficient platelet inhibition with minimal effects on bleeding. In this context, an accurate characterization of P2Y1-R antagonists constitutes an important preliminary step. RESULTS Here, we investigated the pharmacology of P2Y1-R signaling through Gq and β-arrestin pathways in HEK293T cells and in mouse and human platelets using highly sensitive resonance energy transfer-based technologies (BRET/HTRF). We demonstrated that at basal state, in the absence of agonist ligand, P2Y1-R activates Gq protein signaling in HEK293T cells and in mouse and human platelets, indicating that P2Y1-R is constitutively active in physiological conditions. We showed that P2Y1-R also promotes constitutive recruitment of β-arrestin 2 in HEK293T cells. Moreover, the P2Y1-R antagonists MRS2179, MRS2279 and MRS2500 abolished the receptor dependent-constitutive activation, thus behaving as inverse agonists. CONCLUSIONS This study sheds new light on P2Y1-R pharmacology, highlighting for the first time the existence of a constitutively active P2Y1-R population in human platelets. Given the recent interest of P2Y12-R constitutive activity in patients with diabetes, this study suggests that modification of constitutive P2Y1-R signaling might be involved in pathological conditions, including bleeding syndrome or high susceptibility to thrombotic risk. Thus, targeting platelet P2Y1-R constitutive activation might be a promising and powerful strategy for future antiplatelet therapy.
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Qian L, Zhang K, Guo X, Yu M. What happens when chitin becomes chitosan? A single-molecule study. RSC Adv 2023; 13:2294-2300. [PMID: 36741137 PMCID: PMC9841443 DOI: 10.1039/d2ra07303j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 01/09/2023] [Indexed: 01/19/2023] Open
Abstract
Chitin and chitosan are important support structures for many organisms and are important renewable macromolecular biomass resources. Structurally, with the removal of acetyl group, the solubility of chitosan is improved. However, the specific mechanism of solubility enhancement from chitin to chitosan is still unclear. In this study, the atomic force microscopy (AFM)-based single molecule force spectroscopy (SMFS) was used to obtain the single-chain mechanical behavior of chitin and chitosan. The results show that the hydrogen (H)-bonds' state, which can be influenced by the solvent, determines the degree of binding water (solubility) of polysaccharides, and that the binding water energy of a single chitosan chain is 6 times higher than that of chitin in water. Thus, H-bonding is the key to solubility enhancement and can be used to modulate the solubility properties of chitosan. It is expected that our studies can help to understand the structural and functional properties of chitin and chitosan at the single molecule level.
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Affiliation(s)
- Lu Qian
- School of Materials Science and Engineering, South China University of TechnologyGuangzhou 510641China
| | - Kai Zhang
- School of Mechanical Engineering, Sichuan UniversityChengdu 610065China
| | - Xin Guo
- School of Mechanical Engineering, Sichuan UniversityChengdu 610065China
| | - Miao Yu
- School of Mechanical Engineering, Sichuan UniversityChengdu 610065China
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Determination of protein-protein interactions at the single-molecule level using optical tweezers. Q Rev Biophys 2022; 55:e8. [PMID: 35946323 DOI: 10.1017/s0033583522000075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Biomolecular interactions are at the base of all physical processes within living organisms; the study of these interactions has led to the development of a plethora of different methods. Among these, single-molecule (in singulo) experiments have become relevant in recent years because these studies can give insight into mechanisms and interactions that are hidden for ensemble-based (in multiplo) methods. The focus of this review is on optical tweezer (OT) experiments, which can be used to apply and measure mechanical forces in molecular systems. OTs are based on optical trapping, where a laser is used to exert a force on a dielectric bead; and optically trap the bead at a controllable position in all three dimensions. Different experimental approaches have been developed to study protein–protein interactions using OTs, such as: (1) refolding and unfolding in trans interaction where one protein is tethered between the beads and the other protein is in the solution; (2) constant force in cis interaction where each protein is bound to a bead, and the tension is suddenly increased. The interaction may break after some time, giving information about the lifetime of the binding at that tension. And (3) force ramp in cis interaction where each protein is attached to a bead and a ramp force is applied until the interaction breaks. With these experiments, parameters such as kinetic constants (koff, kon), affinity values (KD), energy to the transition state ΔG≠, distance to the transition state Δx≠ can be obtained. These parameters characterize the energy landscape of the interaction. Some parameters such as distance to the transition state can only be obtained from force spectroscopy experiments such as those described here.
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