biostudies-literatureO'Sullivan JJFoundation for the National Institutes of HealthHartwell FoundationNIGMS NIH HHS165-172https://www.ebi.ac.uk/biostudies/studies/S-EPMC9906307biostudies-literatureUnknown4(2)Oxytocin is a 9-amino acid peptide hormone. Since its discovery in 1954, it has most commonly been studied in relation to its role in stimulating parturition and lactation. However, it is now known that oxytocin has a widely diverse set of functions throughout the body including neuromodulation, bone growth, and inflammation. Previous research has suggested that divalent metal ions may be required for oxytocin activity, but the exact metal species and specific pathways have yet to be fully elucidated. In this work, we focus on characterizing copper and zinc bound forms of oxytocin and related analogs through far-UV circular dichroism. We report that Cu(ii) and Zn(ii) bind uniquely to oxytocin and all analogs investigated. Furthermore, we investigate how these metal bound forms may affect downstream signaling of MAPK activation upon receptor binding. We find that both Cu(ii) and Zn(ii) bound oxytocin attenuates the activation of the MAPK pathway upon receptor binding relative to oxytocin alone. Interestingly, we observed that Zn(ii) bound forms of linear oxytocin facilitate increased MAPK signaling. This study lays the foundation for future work on elucidating the metal effects on oxytocin's diverse bioactivity.RSC chemical biologyInvestigation of metal modulation of oxytocin structure receptor-mediated signaling.PMC9906307R35 GM133684NIH MIRA 1R35GM133684-01Uyeda KSStevenson MJO'Sullivan JJHeffern MCfalseInvestigation of metal modulation of oxytocin structure receptor-mediated signaling.Oxytocin is a 9-amino acid peptide hormone. Since its discovery in 1954, it has most commonly been studied in relation to its role in stimulating parturition and lactation. However, it is now known that oxytocin has a widely diverse set of functions throughout the body including neuromodulation, bone growth, and inflammation. Previous research has suggested that divalent metal ions may be required for oxytocin activity, but the exact metal species and specific pathways have yet to be fully elucidated. In this work, we focus on characterizing copper and zinc bound forms of oxytocin and related analogs through far-UV circular dichroism. We report that Cu(ii) and Zn(ii) bind uniquely to oxytocin and all analogs investigated. Furthermore, we investigate how these metal bound forms may affect downstream signaling of MAPK activation upon receptor binding. We find that both Cu(ii) and Zn(ii) bound oxytocin attenuates the activation of the MAPK pathway upon receptor binding relative to oxytocin alone. Interestingly, we observed that Zn(ii) bound forms of linear oxytocin facilitate increased MAPK signaling. This study lays the foundation for future work on elucidating the metal effects on oxytocin's diverse bioactivity.2023-01-01T00:00:00Z2023 Feb2025-04-04T13:08:22.824Z2025-04-04T13:08:22.824ZS-EPMC99063073679402310.1039/d2cb00225f