The neuralized homology repeat 1 domain of Drosophila neuralized mediates nuclear envelope association and delta-dependent inhibition of nuclear import

Neuralized family member NEURL1 is a ubiquitin ligase for the cGMP-specific phosphodiesterase 9A

Neuralized functions as a positive regulator of the Notch pathway by promoting ubiquitination of Notch ligands via its E3 ligase activity, resulting in their efficient endocytosis and signaling. Using a yeast two-hybrid screen, we have identified a cGMP-hydrolysing phosphodiesterase, PDE9A, as a novel interactor and substrate of Neuralized E3 ubiquitin protein ligase 1 (NEURL1). We confirmed this interaction with co-immunoprecipitation experiments and show that both Neuralized Homology Repeat domains of NEURL1 can interact with PDE9A. We also demonstrate that NEURL1 can promote polyubiquitination of PDE9A that leads to its proteasome-mediated degradation mainly via lysine residue K27 of ubiquitin. Our results suggest that NEURL1 acts as a novel regulator of protein levels of PDE9A.

Neuralized-2: expression in human and rodents and interaction with Delta-like ligands

Delta-Notch signaling is a universal cell-cell communication pathway crucial for numerous developmental and physiological processes. Several proteins interact with and regulate the Notch pathway, including the E3 ubiquitin ligase Neuralized (Neur) that influences the stability and activity of Notch ligands. In mammals there are two homologs of Neur, Neur1 and Neur2, that both can interact with Notch ligands Delta-like1 and Jagged1. Here, we show that Neur2, in contrast to Neur1, is highly expressed during embryonic development of the brain and several non-neural tissues and its mRNA levels subside postnatally. In the hippocampal neurons of the adult brain Neur2 transcripts, in contrast to Neur1, are excluded from the dendrites. Neur2 protein has a predominantly cytoplasmic localization. We also show that in addition to Delta-like1, Neur1 and Neur2 interact with another Notch ligand, Delta-like4.

Neuralized is expressed in the alpha/beta lobes of adult Drosophila mushroom bodies and facilitates olfactory long-term memory formation

Memory formation involves multiple molecular mechanisms, the nature and components of which are essential to understand these processes. Drosophila is a powerful model to identify genes important for the formation and storage of consolidated memories because the molecular mechanisms and dependence of these processes on particular brain regions appear to be generally conserved. We present evidence that the highly conserved ubiquitin ligase Neuralized (Neur) is expressed in the adult Drosophila mushroom body (MB) alpha/beta lobe peripheral neurons and is a limiting factor for the formation of long-term memory (LTM). We show that loss of one copy of neur gene results in significant LTM impairment, whereas overexpression of Neur in the peripheral neurons of the alpha/beta lobes of the adult MBs results in a dosage-dependent enhancement of LTM. In contrast, learning, early memories, or anesthesia-resistant memory are not affected. We also demonstrate that the role of Neuralized in LTM formation is restricted within the neurons of the periphery of the alpha/beta lobes, and we suggest that this structural subdivision of the MBs participates in the formation of LTM.