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: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: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: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:Gap junctions mediate intercellular communications across cellular networks in the nervous and the immune systems, while the role in the intestinal innate immunity is poorly understood. Here, we identified that an innexin gene inx-14 encoding one of heterotypic and heteromeric gap junction subunits acts in the gonad to attenuate the intestinal defense through PMK-1/p38 pathway. The RNA-seq analyses revealed that GLP-1/Notch signaling was downregulated, while lysosome, and PMK-1/p38 MAPK signalings were upregulated by the germline-specific inx-14 RNAi in C. elegans. Loss function of either inx-14, or glp-1 exhibited enhanced resistance to PA14 infection and upregulated lysosome and PMK-1/p38 signalings. Additionally, inx-14 knockdown by germline specific RNAi upregulated muscarinic acetylcholine receptor (mAChR) genes gar-1/gar-2/gar-3. We further revealed that acetylcholine mAChR GAR-2/GAR-3 signaling functions in the intestine and downstream of lysosome signaling but upstream of PMK-1/p38 pathway to facilitate the intestinal defense. Our findings reveal a novel role for gonadal gap junction/INX-14 in host intestinal defense against pathogens and expand our understanding the functions of reproductive system in the host intestinal defense.