Neddylation controls dendritic development in the mouse brain.

ANNETTE M. VOGL; MARISA M. BROCKMANN; SEBASTIAN A. GIUSTI; BOLDISZAR CZEH; CHICHUNG LIE; FLORIAN HOLSBOER; WOLFGANG WURST; JAN M. DEUSSING; DAMIAN REFOJO

Cold Spring Harbor

Congreso; The Ubiquitin Family; 2011

Cold Spring Harbor Laboratory

Among the ubiquitin family members, ubiquitin and SUMO were implicated in the regulation of various neurobiological processes as e.g. growth, synaptic plasticity and neurotransmission. Dysregulation of the ubiquitin-proteasome and SUMO-system is associated with several neurological disorders in humans, such as Alzheimers or Parkinsons disease, whereas the function of other ubiquitin-like proteins in the brain, like Nedd8, remains elusive. Analyzing the expression pattern of the molecules of the neddylation cascade via in situ hybridization we found that Nedd8 and Ubc12 mRNA are highly and ubiquitously expressed throughout the embryonic and adult mouse brain. Western blot analysis of mouse brain extracts from different developmental stages showed expression of Ubc12 and revealed a changing pattern of neddylated target proteins. Besides, GFP-Ubc12 and GFP-Nedd8 fusion constructs expressed in primary neurons had somatodendritic and axonal localization and were also present in dendritic spines. To address the role of neddylation during neuronal development we employed dissociated primary neuronal cells as a well characterized model of neuronal growth. Inhibiting neddylation by expressing a dominant-negative Ubc12-C111S or shRNA constructs against Nedd8 and Ubc12 in hippocampal and cortical neurons resulted in a strongly reduced growth and branching of the dendritic tree. Using in utero electroporation of mouse embryos to study cortical and hippocampal development we found that neddylation also controls dendritic growth in vivo. In both, cortical and hippocampal CA1 neurons, the length and branching of growing dendrites were severly impaired when neddylation is blocked. In addition we observed similar defects of the dendritic tree in adult newborn granule neurons of the dentate gyrus, one of the neurogenic niches in the adult mammalian brain, when we injected retroviruses coding for Ubc12-C111S. In biochemical experiments we recently identified PSD95, the most important scaffold molecule of the post-synaptic density in the spine, as a neddylated target and that neddylation regulates the stability of PSD95. In line with these observations, overexpression of PSD95 significantly rescued the dendritic defects of neurons induced by neddylation blockade both in vitro and in vivo. Together our data demonstrate for the first time that the neddylation pathway plays a critical role in dendritic development.