{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,26]],"date-time":"2025-11-26T12:00:04Z","timestamp":1764158404403,"version":"3.46.0"},"reference-count":48,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2025,11,25]],"date-time":"2025-11-25T00:00:00Z","timestamp":1764028800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the National Council for Scientific and Technical Research","award":["PIP CONICET 2023\u20132025 N\u00ba 0433","PIP CONICET 2023-2025 N\u00ba 0027"],"award-info":[{"award-number":["PIP CONICET 2023\u20132025 N\u00ba 0433","PIP CONICET 2023-2025 N\u00ba 0027"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cells"],"abstract":"<jats:p>Inhibition of agonist-induced M2 muscarinic receptor (M2R) activation by functional anti-M2R autoantibodies has been associated with cardiac parasympathetic dysfunction in patients with chronic Chagas disease (CD). This study explored the allosteric nature of that inhibitory effect by assessing the ability of serum IgG from patients with CD and dysautonomia (DCD IgG) to modulate the interaction between M2R and \u03b2-arrestins in HEK 293T cells using bioluminescence resonance energy transfer. DCD IgG alone did not stimulate arrestin-2 or arrestin-3 recruitment. When cells were preincubated with DCD IgG and then treated with carbachol, arrestin-2 translocation decreased in a concentration-dependent manner, while arrestin-3 recruitment remained unaffected. Inhibition curve analysis showed a submaximal inhibitory effect (68.1 \u00b1 2.4%) and a Hill slope less than \u22121 (\u22124.03 \u00b1 0.39). Carbachol concentration\u2013response assays after preincubation with DCD IgG revealed a noncompetitive inhibition of arrestin-2 recruitment, with no change in arrestin-3 translocation. Unlikely, simultaneous exposure to DCD IgG and carbachol potentiated agonist-induced Arr-2 recruitment. We conclude that anti-M2R autoantibodies selectively inhibit agonist-induced arrestin-2 recruitment, acting as negative allosteric modulators of agonist efficacy. The direction of autoantibody-induced allosteric modulation depends on the timing of IgG application relative to the agonist and the duration of receptor exposure to autoantibodies.<\/jats:p>","DOI":"10.3390\/cells14231857","type":"journal-article","created":{"date-parts":[[2025,11,25]],"date-time":"2025-11-25T15:29:47Z","timestamp":1764084587000},"page":"1857","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Negative Allosteric Modulation of Agonist-Induced M2 Muscarinic Receptor\/\u03b2-Arrestin Interaction by Serum Autoantibodies from Patients with Chronic Chagas Disease"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0009-0003-4238-732X","authenticated-orcid":false,"given":"Laura C.","family":"Carrera P\u00e1ez","sequence":"first","affiliation":[{"name":"Laboratorio de Farmacolog\u00eda Molecular, Centro de Estudios Farmacol\u00f3gicos y Bot\u00e1nicos (CEFYBO-CONICET-UBA) y II C\u00e1tedra de Farmacolog\u00eda, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires C1121ABG, Argentina"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-6846-2871","authenticated-orcid":false,"given":"Sabrina P.","family":"Beltrame","sequence":"additional","affiliation":[{"name":"Laboratorio de Farmacolog\u00eda Molecular, Centro de Estudios Farmacol\u00f3gicos y Bot\u00e1nicos (CEFYBO-CONICET-UBA) y II C\u00e1tedra de Farmacolog\u00eda, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires C1121ABG, Argentina"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0006-1135-3233","authenticated-orcid":false,"given":"Sergio R.","family":"Auger","sequence":"additional","affiliation":[{"name":"Hospital Donaci\u00f3n Francisco Santojanni, Buenos Aires C1408INH, Argentina"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-8493-4857","authenticated-orcid":false,"given":"Ahmad H.","family":"Sabra","sequence":"additional","affiliation":[{"name":"Hospital Donaci\u00f3n Francisco Santojanni, Buenos Aires C1408INH, Argentina"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-7898-2908","authenticated-orcid":false,"given":"Claudio R.","family":"Bilder","sequence":"additional","affiliation":[{"name":"Laboratorio de Neurogastroenterolog\u00eda, Fundaci\u00f3n Favaloro-Hospital Universitario, Buenos Aires C1093AAS, Argentina"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5357-2107","authenticated-orcid":false,"given":"Isabel M.","family":"Irurzun","sequence":"additional","affiliation":[{"name":"Centro de Simulaci\u00f3n Computacional para Aplicaciones Tecnol\u00f3gicas (CSC-CONICET), Buenos Aires C1425FQD, Argentina"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9070-4858","authenticated-orcid":false,"given":"Claudia I.","family":"Waldner","sequence":"additional","affiliation":[{"name":"Laboratorio de Inmunidad Celular y Molecular, Centro de Estudios Farmacol\u00f3gicos y Bot\u00e1nicos (CEFYBO-CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires C1121ABG, Argentina"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2184-1111","authenticated-orcid":false,"given":"Juan C.","family":"Goin","sequence":"additional","affiliation":[{"name":"Laboratorio de Farmacolog\u00eda Molecular, Centro de Estudios Farmacol\u00f3gicos y Bot\u00e1nicos (CEFYBO-CONICET-UBA) y II C\u00e1tedra de Farmacolog\u00eda, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires C1121ABG, Argentina"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,25]]},"reference":[{"key":"ref_1","first-page":"100881","article-title":"The epidemiology of Chagas disease in the Americas","volume":"37","author":"Cucunuba","year":"2024","journal-title":"Lancet Reg. 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