{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nLYNX1 is an endogenous prototoxin that belongs to the Ly6/neurotoxin superfamily and modulates the activity of nicotinic acetylcholine receptors (nAChRs) via allosteric interactions. Structural studies—including NMR analyses of water‐soluble variants—have revealed that LYNX1 shares a conserved three‐finger motif similar to snake α‐neurotoxins while acting to fine‐tune nAChR responsiveness by reducing receptor sensitivity to high concentrations of acetylcholine. These findings, established using biochemical and mutagenesis approaches, support a role for LYNX1 as a natural “brake” on cholinergic signaling."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "3"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn non‐neuronal tissues, such as the lung, keratinocytes, and ovarian epithelium, LYNX1 similarly serves to restrain nAChR signaling. In normal lung epithelium, LYNX1 limits nicotine‐induced upregulation of receptor levels and downstream proliferative signaling. Experimental data indicate that loss or reduction of LYNX1 is associated with enhanced cell growth in lung cancer models, while its ectopic expression can inhibit proliferation in lung adenocarcinoma cells. Moreover, diminished LYNX1 expression in ovarian serous cystadenocarcinoma correlates with poorer clinical outcomes, and keratinocytes have been shown to express LYNX1—suggesting a broader role in epithelial homeostasis that warrants further investigation."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "4", "end_ref": "7"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn the central nervous system, LYNX1 modulates neuronal nAChRs—including receptors in dopaminergic neurons—to influence neurotransmitter release and behavioral responses related to nicotine signaling. Detailed mutagenesis and peptide fragment studies have mapped the critical binding regions of LYNX1 and affirmed its capacity to modulate receptor affinity and desensitization kinetics. These insights, along with emerging evidence from pharmacological studies, underscore the potential of targeting LYNX1 or its interaction surfaces as a novel, allosteric strategy for therapeutically modulating cholinergic circuits in neuropsychiatric disorders and conditions associated with nicotine abuse."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "8", "end_ref": "10"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Pingfang Song, Harmanjatinder S Sekhon, Xiao Wen Fu, et al. 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"}, {"type": "b", "children": [{"type": "t", "text": "NMR structure and action on nicotinic acetylcholine receptors of water-soluble domain of human LYNX1."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2011)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M110.189100"}], "href": "https://doi.org/10.1074/jbc.M110.189100"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "21252236"}], "href": "https://pubmed.ncbi.nlm.nih.gov/21252236"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Ekaterina N Lyukmanova, Mikhail A Shulepko, Svetlana L Buldakova, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Water-soluble LYNX1 residues important for interaction with muscle-type and/or neuronal nicotinic receptors."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2013)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M112.436576"}], "href": "https://doi.org/10.1074/jbc.M112.436576"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "23585571"}], "href": "https://pubmed.ncbi.nlm.nih.gov/23585571"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Xiao Wen Fu, Ping Fang Song, Eliot R Spindel "}, {"type": "b", "children": [{"type": "t", "text": "Role of Lynx1 and related Ly6 proteins as modulators of cholinergic signaling in normal and neoplastic bronchial epithelium."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Int Immunopharmacol (2015)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.intimp.2015.05.022"}], "href": "https://doi.org/10.1016/j.intimp.2015.05.022"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "26025503"}], "href": "https://pubmed.ncbi.nlm.nih.gov/26025503"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "Yasuhiro Moriwaki, Kiyoko Takada, Shoutaro Tsuji, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Transcriptional regulation of SLURP2, a psoriasis-associated gene, is under control of IL-22 in the skin: A special reference to the nested gene LYNX1."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Int Immunopharmacol (2015)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.intimp.2015.05.030"}], "href": "https://doi.org/10.1016/j.intimp.2015.05.030"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "26033490"}], "href": "https://pubmed.ncbi.nlm.nih.gov/26033490"}]}, {"type": "r", "ref": 6, "children": [{"type": "t", "text": "Maxim Bychkov, Zakhar Shenkarev, Mikhail Shulepko, et al. 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