Tissue-type plasminogen activator protects neurons from excitotoxin-induced cell death via activation of the ERK1/2-CREB-ATF3 signaling pathway.
The release of the serine proteinase tissue-type plasminogen activator (tPA) from cerebral cortical neurons has a neuroprotective effect in the ischemic brain. Because excitotoxicity is a basic mechanism of ischemia-induced cell death, here we investigated the effect of tPA on excitotoxin-induced neuronal death. We report that genetic overexpression of neuronal tPA or treatment with recombinant tPA renders neurons resistant to the harmful effects of an excitotoxic injury in vitro and in vivo. We found that at concentrations found in the ischemic brain, tPA interacts with synaptic but not extrasynaptic NMDARs. This effect is independent of tPA's proteolytic properties and leads to a rapid and transient phosphorylation of the extracellular signal regulated kinases1/2 (ERK1/2), with ERK1/2-mediated activation of the cAMP response element binding protein (CREB) and induction of the neuroprotective CREB-regulated activating transcription factor 3 (Atf3). In line with these observations, Atf3 down-regulation abrogates the protective effect of tPA against excitotoxin-induced neuronal death. Our data indicate that tPA preferentially activates synaptic NMDARs via a plasminogen-independent mechanism turning on a cell signaling pathway that protects neurons from the deleterious effects of excitotoxicity.
Department of Neurology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA, USA.
Fang
F
Wu
Ramiro
R
Echeverry
Jialing
J
Wu
Jie
J
An
Woldeab B
WB
Haile
Deborah S
DS
Cooper
Marcela
M
Catano
Manuel
M
Yepes
D051700:Activating Transcription Factor 3 / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D016923:Cell Death / Q000502:physiology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016202:N-Methylaspartate / Q000633:toxicity; D009474:Neurons / Q000378:metabolism*; D009498:Neurotoxins / Q000633:toxicity; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D010959:Tissue Plasminogen Activator / Q000378:metabolism* / Q000494:pharmacology
D051700:Activating Transcription Factor 3; D017362:Cyclic AMP Response Element-Binding Protein; D048049:Extracellular Signal-Regulated MAP Kinases; D016202:N-Methylaspartate; D009498:Neurotoxins; D016194:Receptors, N-Methyl-D-Aspartate; D010959:Tissue Plasminogen Activator; C490449:ATF3 protein, human