Project description:This study shows that chemically and pharmacodynamically distinct agonists acting on the same GPCR can produce indistinguishable cellular responses and that this uniformity is conferred by endosomal signaling The ability of chemically distinct ligands to produce different effects on the same G protein-coupled receptor (GPCR) has interesting therapeutic implications but, if excessively propagated downstream, would introduce biological 'noise' compromising cognate ligand detection We asked if cells have the ability to limit the degree to which chemical diversity imposed at the ligand-GPCR interface is propagated to the downstream signal We carried out an unbiased analysis of the integrated cellular response elicited by two chemically and pharmacodynamically diverse β-adrenoceptor agonists, isoproterenol and salmeterol We show that both ligands generate an identical integrated response, and that this stereotyped output requires endocytosis We further demonstrate that the endosomal β2-AR signal confers uniformity on the downstream response because it is highly sensitive and saturable Based on these findings, we propose that GPCR signaling from endosomes functions as a biological noise filter to enhance reliability of cognate ligand detection
Project description:Many G protein-coupled receptors (GPCRs) trigger a second phase of G protein-dependent signaling from internal membranes after agonist-induced endocytosis. However, individual GPCRs differ significantly in their ability to internalize after activation, and it remains unclear if this confers selectivity on cellular signaling through natively coexpressed GPCRs. We addressed this question by examining the activation of the cyclic AMP (cAMP) / cAMP-dependent protein kinase (PKA) pathway by three ligands that stimulate three distinct, endogenously coexpressed GPCRs in HEK293 cells: isoproterenol (Iso) which primarily activates the β2-adrenergic receptor (β2AR), vasoactive intestinal peptide (VIP) which primarily activates the vasoactive intestinal peptide receptor 1 (VIPR1/VPAC1), and 5'-N-ethylcarboxamidoadenosine (NECA) which primarily activates the adenosine 2B receptor (A2BR). Using location-targeted biosensors and a transcriptional reporter, we demonstrate that each ligand triggers a unique cellular signaling profile and that these responses are differentially sensitive to endocytic inhibition. VIP elicited a response that was endocytosis-dependent at every level in the pathway tested, from upstream global cAMP elevation to downstream activation of nuclear PKA, while Iso elicited a response that was dependent on endocytosis selectively at downstream steps. In contrast, NECA robustly activated the entire cAMP signaling cascade independently of endocytosis, consistent with our observation that human A2BR does not robustly internalize after activation. We conclude that endocytosis indeed sculpts downstream cAMP signaling by GPCRs in a receptor-specific manner. Our results add to the evolving view of compartmentalized signaling in the cAMP / PKA pathway and suggest that differences in GPCR trafficking can encode receptor-specific signaling profiles through a shared signal transduction pathway.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:To elucidate the epithelial cell diversity within the nasal inferior turbinates, a comprehensive investigation was conducted comparing control subjects to individuals with house dust mite-induced allergic rhinitis. This study aimed to delineate the differential expression profiles and phenotypic variations of epithelial cells in response to allergic rhinitis. This research elucidated distinct subpopulations and rare cell types of epithelial cells within the nasal turbinates, discerning alterations induced by allergic rhinitis. Furthermore, by interrogating transcriptomic signatures, the investigation provided novel insights into the cellular dynamics and immune responses underlying allergic rhinitis pathogenesis
