P3–038: A novel PKC‐dependent phosphorylation of doublecortin: Potential implications in the context of excitotoxicity
Year: 2013
Type: article
Abstract: Excitotoxicity is a neuronal condition marked by the overactivation of ionotropic glutamate receptors, leading to an excessive elevation of intracellular calcium levels and profound cytoskeletal reorganization. Such process has been implicated in several neurodegenerative disorders. Neurogenesis in the adult human brain has been shown and also implicated in neurodegenerative diseases. Doublecortin (Dcx) is a central molecule in neurogenesis, expressed by neuronal precursor cells and immature neurons in embryonic and adult brains. It functions as a classical microtubule -associated protein (MAP) whose phosphorylation regulates its affinity for microtubules, thus modulating microtubule dynamics involved in cytoskeletal architecture, mitotic spindle formation, microtubule-based transport or neuronal migration. Previous studies reported that Dcx can be phosphorylated by various kinases, such as Cdk5, JNK or MAPK. Western blot, Immunoprecipitation. Here we describe a novel PKC-dependent phosphorylation of Dcx, which is transiently but rapidly induced by glutamate in primary cortical neurons. Interestingly, other agonists (NMDA, kainate, AMPA) of ionotropic glutamatereceptors or KCl-induced depolarization can also induce this phosphorylation in primary cultures. Besides, this phenomenon is dependent on the NR2B subunit of NMDA receptors since the Dcx phosphorylation was abolished by NMDA receptor inhibitors (MK801, D-APV) or NR2B specific inhibitor (Ifenprodil). Moreover, EGTA or the VGCC inhibitor Nifedipine completely blocked the phosphorylation, which was also induced by calcium ionophores, indicative of a calcium-dependent phenomenon. Finally, the Dcx phosphorylation was abolished by the PKC inhibitor chelerythrine, which confirms for the first time the predicted Dcx phosphorylation by PKC. These data provide new insight into the mechanisms regulating DCX phosphorylation. Also, it demonstrates a potential role for Dcx in immature neuron during excitotoxic process and raises the possibility that Dcx-positive cells may have functional significance in the pathophysiology of various neurodegenerative diseases.
Source: Alzheimer s & Dementia
Institution: Icahn School of Medicine at Mount Sinai
Language: English
Subfield: Cellular and Molecular Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W2088530002