Background: Polycystic liver diseases (PLD) are genetic disorders characterized by progressive growth of numerous liver cysts, causing significant morbidity. Previous studies revealed genes affecting protein biogenesis and more recently, protein SUMOylation, a posttranslational modification (PTM), has been implicated in PLD pathobiology. On the other hand, protein NEDDylation is a newly-characterized PTM, modulating a plethora of biological processes and its dysregulation is associated with development and progression of several human diseases. In this regard, the role of NEDDylation in PLD remains elusive and unraveling its role in the pathogenesis of these genetic disorders could open new avenues for the development of novel treatments in the future. Objective: To explore the role of protein NEDDylation in PLD and its potential therapeutic regulatory value. Methods: Expression and function of NEDDylation, including response to Pevonedistat (first-in-class selective inhibitor of the NEDDylation E1 enzyme NAE1), were assessed in vitro. Proteomic analyses of immunoprecipitated NEDDylated proteins were performed by mass spectrometry.