title: Generation and functional analysis of monoclonal antibodies against the second extracellular loop of human M3 muscarinic acetylcholine receptor.
abstract: The M3 muscarinic acetylcholine receptor (M3R) plays a crucial role in the activation of salivary and lachrymal glands. The M3R contains four extracellular domains (the N-terminal, and the first, second, and third extracellular loops), and we recently detected antibodies against each of these four domains in a subgroup of patients with Sjögren's syndrome (SS). Functional analysis indicated that the influence of such anti-M3R antibodies on salivary secretion might differ based on the epitopes to which they bind. To clarify the relationship between B-cell epitopes on the M3R and its function, we generated two hybridomas producing anti-M3R monoclonal antibodies against the second extracellular loop of M3R (anti-M3R(2nd) mAbs) and analyzed their function by Ca(2+)-influx assays, using a human salivary gland (HSG) cell line. These two anti-M3R(2nd) mAbs suppressed Ca(2+)-influx in the HSG cells induced by cevimeline stimulation, suggesting that autoantibodies against the second extracellular loop of M3R could be involved in salivary dysfunction in patients with SS.
authors.affiliation: Division of Clinical Immunology, Doctoral Programs in Clinical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Tsuboi
authors.forename: Yumi
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Mana
authors.initials: M
authors.lastname: Iizuka
authors.forename: Naomi
authors.initials: N
authors.lastname: Matsuo
authors.forename: Isao
authors.initials: I
authors.lastname: Matsumoto
authors.forename: Takayuki
authors.initials: T
authors.lastname: Sumida
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis* / Q000276:immunology / Q000494:pharmacology; D001323:Autoantibodies / Q000096:biosynthesis* / Q000276:immunology / Q000494:pharmacology; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D006801:Humans; D006825:Hybridomas; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007155:Immunologic Factors / Q000096:biosynthesis* / Q000276:immunology / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology; D017433:Protein Structure, Secondary; D043587:Receptor, Muscarinic M3 / Q000737:chemistry / Q000276:immunology*; D012469:Salivary Glands / Q000187:drug effects / Q000378:metabolism; D012859:Sjogren's Syndrome / Q000276:immunology; D013047:Specific Pathogen-Free Organisms
chemical_list: D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D018985:Epitopes, B-Lymphocyte; D007143:Immunoglobulin Heavy Chains; D007155:Immunologic Factors; D010455:Peptides; D043587:Receptor, Muscarinic M3