Urokinase-type plasminogen activator promotes dendritic spine recovery and improves neurological outcome following ischemic stroke

• Published in: The Journal of neuroscience 2014-10, Vol.34 (43), p.14219-14232
• Main Authors: Wu, Fang, Catano, Marcela, Echeverry, Ramiro, Torre, Enrique, Haile, Woldeab B, An, Jie, Chen, Changhua, Cheng, Lihong, Nicholson, Andrew, Tong, Frank C, Park, Jaekeun, Yepes, Manuel
• Format: Article
• Language: English
• Subjects: Animals; Brain Ischemia - drug therapy; Brain Ischemia - enzymology; Brain Ischemia - pathology; Cells, Cultured; Dendritic Spines - drug effects; Dendritic Spines - metabolism; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nervous System Diseases - drug therapy; Nervous System Diseases - enzymology; Nervous System Diseases - pathology; Protein Binding - physiology; Receptors, Urokinase Plasminogen Activator - metabolism; Recovery of Function - drug effects; Recovery of Function - physiology; Stroke - drug therapy; Stroke - enzymology; Stroke - pathology; Treatment Outcome; Urokinase-Type Plasminogen Activator - metabolism; Urokinase-Type Plasminogen Activator - pharmacology; Urokinase-Type Plasminogen Activator - therapeutic use
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/jneurosci.5309-13.2014

Spines are dendritic protrusions that receive most of the excitatory input in the brain. Early after the onset of cerebral ischemia dendritic spines in the peri-infarct cortex are replaced by areas of focal swelling, and their re-emergence from these varicosities is associated with neurological recovery after acute ischemic stroke (AIS). Urokinase-type plasminogen activator (uPA) is a serine proteinase that plays a central role in tissue remodeling via binding to the urokinase plasminogen activator receptor (uPAR). We report that cerebral cortical neurons release uPA during the recovery phase from ischemic stroke in vivo or hypoxia in vitro. Although uPA does not have an effect on ischemia- or hypoxia-induced neuronal death, genetic deficiency of uPA (uPA(-/-)) or uPAR (uPAR(-/-)) abrogates functional recovery after AIS. Treatment with recombinant uPA after ischemic stroke induces neurological recovery in wild-type and uPA(-/-) but not in uPAR(-/-) mice. Diffusion tensor imaging studies indicate that uPA(-/-) mice have increased water diffusivity and decreased anisotropy associated with impaired dendritic spine recovery and decreased length of distal neurites in the peri-infarct cortex. We found that the excitotoxic injury induces the clustering of uPAR in dendritic varicosities, and that the binding of uPA to uPAR promotes the reorganization of the actin cytoskeleton and re-emergence of dendritic filopodia from uPAR-enriched varicosities. This effect is independent of uPA's proteolytic properties and instead is mediated by Rac-regulated profilin expression and cofilin phosphorylation. Our data indicate that binding of uPA to uPAR promotes dendritic spine recovery and improves functional outcome following AIS.