PRKN and Parkinson disease: For example, PRKN is a risk factor for both learning and memory disorders, as well as PD, as it encodes a component of a multiprotein E3 ubiquitin ligase complex (Lubbe et al., 2021), whose upregulation may be linked to the misregulation of proteostasis in the aged hippocampus (Fig. 1F) (Costa-Mattioli and Walter, 2020).