Evidence that melatonin downregulates Nedd4-1 E3 ligase and its role in cellular survival

• Published in: Toxicology and applied pharmacology Vol. 379; p. 114686
• Main Authors: Yalcin, Esra, Beker, Mustafa C., Turkseven, Seyma, Caglayan, Berrak, Gurel, Busra, Kilic, Ulkan, Caglayan, Ahmet B., Kalkan, Rabia, Baykal, Ahmet T., Kelestemur, Taha, Kilic, Ertugrul
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.09.2019
• Subjects: Melatonin; Nedd4-1; Proteasome; Proteomic; Ubiquitin; Ubiquitin proteosome system; Ubiquitin; Melatonin; Proteomic; Ubiquitin proteosome system; Nedd4-1; Proteasome
• ISSN: 0041-008X; 1096-0333
• DOI: 10.1016/j.taap.2019.114686

Indolamine melatonin structurally resembles non-covalent proteasome inhibitors; however, the role of ubiquitin proteasome system (UPS) in neuronal survival and how melatonin carries out UPS inhibition remain largely unknown. With the use of melatonin treated cells, we evaluated the expression of Nedd4-1, an E3 ligase, how melatonin regulates its activity and its relationship with neuronal survival. Nedd4-1 was upregulated in the hypoxic condition in both control and Nedd4-1 overexpressed cells and melatonin treatment reversed its expression in both normoxic and hypoxic conditions, which was associated with increased cellular survival. Melatonin had no effect on the expression of Nedd4-1 at mRNA level. However, when melatonin was administered along with protein synthesis inhibitor cycloheximide, protein level of Nedd4-1 was further reduced, indicating that melatonin possibly downregulates Nedd4-1 after its synthesis. Notably, co-immunoprecipitation analyses followed by Liquid chromatography–Mass Spectrometry (LC-MS/MS) revealed that melatonin may dissociate ribosomal proteins, such as RS19, RL23A, and nucleophosmin from Nedd4-1, while 40S ribosomal protein S7 and 60S ribosomal protein L35 came into contact with Nedd4-1 upon melatonin treatment. By using IPA analyses, we obtained further data indicated novel target molecules of melatonin in hypoxic conditions, including OTOF, SF3B2, IPO5, ST13, FGFR3, Mx1/Mx2, playing roles in RNA splicing and trafficking, growth factor and interferon signaling. Here, we described a new insight into the role of melatonin in UPS functioning by proposing a molecular mechanism through which melatonin regulates Nedd4-1. [Display omitted] •Melatonin regulates UPS by inhibiting E3 ligase, Nedd4-1.•Melatonin has any significant effect on lid-, core-, and base- proteins of UPS.•Nedd4-1 overexpression alone increases cell death in the hypoxic condition.•OTOF, SF3B2, FGFR3, and Mx1/Mx2 are possible target molecules of melatonin.•Proteome-wide analysis reveals novel aspects of how melatonin functions.