Doublecortin Microtubule Affinity Is Regulated by a Balance of Kinase and Phosphatase Activity at the Leading Edge of Migrating Neurons

• Published in: Neuron (Cambridge, Mass.) Mass.), 2004-01, Vol.41 (2), p.203-213
• Main Authors: Schaar, Bruce T, Kinoshita, Kazuhisa, McConnell, Susan K
• Format: Article
• Language: English
• Subjects: Animals; Bands; Cell culture; Cell division; Cell Membrane - enzymology; Cell Membrane - metabolism; Cell Movement - drug effects; Cell Movement - physiology; Cells, Cultured; Cyclic AMP-Dependent Protein Kinases - metabolism; Cyclin-Dependent Kinase 5; Cyclin-Dependent Kinases - metabolism; Cyclin-Dependent Kinases - physiology; Cytoskeleton; Cytoskeleton - metabolism; Enzyme Inhibitors - pharmacology; Humans; Immunohistochemistry; Kinases; Microtubule-Associated Proteins - metabolism; Microtubule-Associated Proteins - physiology; Microtubules - drug effects; Microtubules - metabolism; Migration; Motility; Mutation; Mutation - physiology; Nerve Tissue Proteins - biosynthesis; Neurites - metabolism; Neurons; Neurons - enzymology; Neurons - metabolism; Neurons - physiology; Neuropeptides - metabolism; Neuropeptides - physiology; Okadaic Acid - pharmacology; Phosphoric Monoester Hydrolases - metabolism; Phosphorylation; Proteins; Rats; Rats, Sprague-Dawley; Science programs; Serine - genetics; Spectrum analysis
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/S0896-6273(03)00843-2

Doublecortin (Dcx) is a microtubule-associated protein that is mutated in X-linked lissencephaly (X-LIS), a neuronal migration disorder associated with epilepsy and mental retardation. Although Dcx can bind ubiquitously to microtubules in nonneuronal cells, Dcx is highly enriched in the leading processes of migrating neurons and the growth cone region of differentiating neurons. We present evidence that Dcx/microtubule interactions are negatively controlled by Protein Kinase A (PKA) and the MARK/PAR-1 family of protein kinases. In addition to a consensus MARK site, we identified a serine within a novel sequence that is crucial for the PKA- and MARK-dependent regulation of Dcx's microtubule binding activity in vitro. This serine is mutated in two families affected by X-LIS. Immunostaining neurons with an antibody that recognizes phosphorylated substrates of MARK supports the conclusion that Dcx localization and function are regulated at the leading edge of migrating cells by a balance of kinase and phosphatase activity.