Project description:Previously M3 muscarinic acetylcholine receptore (M3R) reactive Th1 cells were identified, and here, M3R reactive Th17 cells were identified in peripheral blood of primary Sjögren’s syndrome patients using ELISpot method. To assess TCR repertoire overlap between identified M3R reactive Th17 cells, and salivary gland infiltrating T cells, we performed high throughput TCR sequencing of those cells from pSS patient.
Project description:The M3 muscarinic acetylcholine receptor (CHRM3) is predominantly expressed in the basal epidermal layer where it mediates the effects of the auto/paracrine cytotransmitter acetylcholine. Patients with the autoimmune blistering disease pemphigus develop autoantibodies to CHRM3 and show alterations in keratinocyte adhesion, proliferation and differentiation, suggesting that CHRM3 controls these cellular functions. Chrm3 mice display altered epidermal morphology resembling that seen in patients with pemphigus vulgaris. Here, we characterized the cellular and molecular mechanisms whereby CHRM3 controls epidermal structure and function. We used single cell (sc)RNA-seq to evaluate keratinocyte heterogeneity and identify differentially expressed genes in specific subpopulations of epidermal cells in Chrm3 KO neonatal mice.
Project description:Muscarinic acetylcholine receptor M3 (M3) and its downstream effector Gq/11 are critical drug development targets given their involvement in numerous physiological processes and diseases. Although a cryo-electron microscopy study previously defined the structure of the M3-miniGq complex, the lack of information on the intracellular loop 3 (ICL3) of M3 and α-helical domain (AHD) of Gαq has made it difficult to comprehend the molecular mechanism of M3-Gq coupling fully. Here, we present the molecular mechanism underlying the dynamic interactions between the wild-type full-length M3 and heterotrimeric Gq using hydrogen-deuterium exchange mass spectrometry and NanoLuc Binary Technology-based cell systems. This study suggests potential binding interfaces between M3 and Gq in pre-assembled and fully active nucleotide-free complexes. In addition to well-known binding interfaces, we observed the interaction of long ICL3 with Gβγ. Furthermore, M3 ICL3 negatively affected M3-Gq coupling, and the Gαq AHD underwent unique conformational changes during M3-Gq coupling. Therefore, we propose a comprehensive molecular mechanism of M3-Gq coupling by analyzing previously well-defined binding interfaces and neglected regions, such as M3 ICL3 and the Gαq AHD.
Project description:M3 muscarinic acetylcholine receptor (M3R) is one of the autoantigens associated with Sjögren's syndrome (SS) and is localized in exocrine glands where disease-specific inflammation occurs. The inflammatory lesion is characterized by infiltration of CD4+ T cells, including clonally expanded Th17 cells. We undertook this study to identify circulating M3R-specific Th17 cells and to determine functional properties of those cells. Using the enzyme-linked immunospot assay (ELISpot) method, we identified M3R-reactive Th17 cells in the peripheral blood of patients with primary SS (pSS). Among 10 examined pSS patients, 10 healthy subjects (HS), and 5 IgG4-related disease (IgG4-RD) patients, M3R-reactive IL-17 secreting cells were significantly increased in 5 pSS patients specifically. The most common T cell epitope, which was analyzed and confirmed by coculture of isolated CD4+ T cells with antigen presenting cells plus M3R peptides in vitro, was peptide 83-95 of M3R. Peptide recognition was partly in an HLA-DR-restricted manner, confirmed by blocking assay. M3R-reactive Th17 cells positivity correlated with higher titers of anti-M3R antibodies, whose systemic disease activity score tended to be higher. Our studies highlight the role of tissue-specific autoantigen-derived circulating Th17 cells in pSS, for which further work might lead to antigen-specific targeted therapy.
Project description:In contrast to most peripheral tissues where multiple subtypes of muscarinic acetylcholine receptor (mAChR) coexist, with each of them playing its part in the orchestra of parasympathetic innervation, the myocardium has been traditionally considered to possess a single mAChR subtype. Although there is much evidence to support the notion that one receptor subtype (M2) orchestrates myocardial muscarinic transduction, there is emerging evidence that M1 and M3 receptors are also expressed and are of potential physiological, pathophysiological and pharmacological relevance. Clarifying this issue has a profound impact on our thinking about the cholinergic control of the heart function and disease and approaches to new drug development for the treatment of heart disease associated with parasympathetic dysfunction. This review article presents evidence for the presence of the M3 receptor subtype in the heart, and analyzes the controversial data from published pharmacological, functional and molecular studies. The potential roles of the M3 receptors, in parasympathetic control of heart function under normal physiological conditions and in heart failure, myocardial ischemia and arrhythmias, are discussed. On the basis of these considerations, we have made some proposals concerning the future of myocardial M3 receptor research.
Project description:The M3 muscarinic acetylcholine receptor is predominantly expressed in the basal epidermal layer where it mediates the effects of the autocrine/paracrine cytotransmitter acetylcholine. Patients with the autoimmune blistering disease pemphigus develop autoantibodies to M3 muscarinic acetylcholine receptor and show alterations in keratinocyte adhesion, proliferation, and differentiation, suggesting that M3 muscarinic acetylcholine receptor controls these cellular functions. Chmr3-/- mice display altered epidermal morphology resembling that seen in patients with pemphigus vulgaris. In this study, we characterized the cellular and molecular mechanisms through which M3 muscarinic acetylcholine receptor controls epidermal structure and function. We used single-cell RNA sequencing to evaluate keratinocyte heterogeneity and identify differentially expressed genes in specific subpopulations of epidermal cells in Chmr3-/- neonatal mice. We found that Chmr3-/- mice feature abnormal epidermal morphology characterized by accumulation of nucleated basal cells, shrinkage of basal keratinocytes, and enlargement of intercellular spaces. These morphologic changes were associated with upregulation of cell proliferation genes and downregulation of genes contributing to epidermal differentiation, extracellular matrix formation, intercellular adhesion, and cell arrangement. These findings provide, to our knowledge, previously unreported insights into how acetylcholine controls epidermal differentiation and lay a groundwork for future translational studies evaluating the therapeutic potential of cholinergic drugs in dermatology.
Project description:Acetylcholine, the first neurotransmitter to be identified, exerts many of its physiological actions via activation of a family of G-protein-coupled receptors (GPCRs) known as muscarinic acetylcholine receptors (mAChRs). Although the five mAChR subtypes (M1-M5) share a high degree of sequence homology, they show pronounced differences in G-protein coupling preference and the physiological responses they mediate. Unfortunately, despite decades of effort, no therapeutic agents endowed with clear mAChR subtype selectivity have been developed to exploit these differences. We describe here the structure of the G(q/11)-coupled M3 mAChR ('M3 receptor', from rat) bound to the bronchodilator drug tiotropium and identify the binding mode for this clinically important drug. This structure, together with that of the G(i/o)-coupled M2 receptor, offers possibilities for the design of mAChR subtype-selective ligands. Importantly, the M3 receptor structure allows a structural comparison between two members of a mammalian GPCR subfamily displaying different G-protein coupling selectivities. Furthermore, molecular dynamics simulations suggest that tiotropium binds transiently to an allosteric site en route to the binding pocket of both receptors. These simulations offer a structural view of an allosteric binding mode for an orthosteric GPCR ligand and provide additional opportunities for the design of ligands with different affinities or binding kinetics for different mAChR subtypes. Our findings not only offer insights into the structure and function of one of the most important GPCR families, but may also facilitate the design of improved therapeutics targeting these critical receptors.
Project description:Muscarinic acetylcholine receptor M3 (M3) and its downstream effector Gq/11 are critical drug development targets due to their involvement in physiopathological processes. Although the structure of the M3-miniGq complex was recently published, the lack of information on the intracellular loop 3 (ICL3) of M3 and extensive modification of Gαq impedes the elucidation of the molecular mechanism of M3-Gq coupling under more physiological condition. Here, we describe the molecular mechanism underlying the dynamic interactions between full-length wild-type M3 and Gq using hydrogen-deuterium exchange mass spectrometry and NanoLuc Binary Technology-based cell systems. We propose a detailed analysis of M3-Gq coupling through examination of previously well-defined binding interfaces and neglected regions. Our findings suggest potential binding interfaces between M3 and Gq in pre-assembled and functionally active complexes. Furthermore, M3 ICL3 negatively affected M3-Gq coupling, and the Gαq AHD underwent unique conformational changes during M3-Gq coupling.
Project description:BackgroundCholinergic signaling via muscarinic acetylcholine receptors (mAChR) is known to influence various physiological functions. In bone, M3 mAChR and M5 mAChR were identified on the membrane of osteoblast-like cells. M3 mAChR seems to be particularly relevant for bone physiology, as signaling via this receptor was reported to increase bone formation and decrease bone resorption. Thus, in the present study we investigated the relative mRNA expression of M3 and M5 mAChR in bones of a rat osteoporosis model.Material and methodsOsteoporosis was induced in Sprague-Dawley rats by bilateral ovariectomy and additional feeding of a diet deficient in calcium, vitamins C, D2, D3, and phosphorus, and free of soy and phytoestrogen. After a period of 3, 12, and 14 months, relative mRNA expression of M3 mAChR and M5 mAChR was analyzed in the 11th thoracic vertebra by real-time RT-PCR.ResultsRelative mRNA expression of M3 mAChR was significantly reduced in bones of osteoporotic rats compared to sham operated animals that served as controls. Further, M3 mAChR mRNA expression was significantly down-regulated when comparing 14-month osteoporotic rats to 3-month osteoporotic rats. Relative M5 mAChR mRNA was expressed to a lesser extent than M3 mAChR and did not show significant differences in mRNA expression level between the experimental groups.ConclusionsM3 mAChR mRNA expression was reduced upon induction of osteoporosis and progression of disease was associated with further decrease of this receptor, indicating that M3 mAChR is involved in the development and regulation of osteoporosis.