Excitotoxicity-related endocytosis in cortical neurons.
Recent studies showed that endocytosis is enhanced in neurons exposed to an excitototoxic stimulus. We here confirm and analyze this new phenomenon using dissociated cortical neuronal cultures. NMDA-induced uptake (FITC-dextran or FITC or horseradish peroxidase) occurs in these cultures and is due to endocytosis, not to cell entry through damaged membranes; it requires an excitotoxic dose of NMDA and is dependent on extracellular calcium, but occurs early, while the neuron is still intact and viable. It involves two components, NMDA-induced and constitutive, with different characteristics. Neither component involves specific binding of the endocytosed molecules to a saturable receptor. Strikingly, molecules internalized by the NMDA-induced component are targeted to neuronal nuclei. This component, but not the constitutive one, is blocked by a c-Jun N-terminal protein kinase inhibitor. In conclusion, an excitotoxic dose of NMDA triggers c-Jun N-terminal protein kinase-dependent endocytosis in cortical neuronal cultures, providing an in vitro model of the excitotoxicity-induced endocytosis reported in intact tissues.
Vaslin
A
A
Département de Biologie Cellulaire et de Morphologie, University of Lausanne, Switzerland. anne.vaslin@unil.ch
Puyal
J
J
Borsello
T
T
Clarke
P G H
PG
D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D003911:Dextrans; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008954:Models, Biological; D016202:N-Methylaspartate / Q000633:toxicity; D009410:Nerve Degeneration / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009498:Neurotoxins / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley
D003911:Dextrans; D018690:Excitatory Amino Acid Agonists; D009498:Neurotoxins; C015219:fluorescein isothiocyanate dextran; D016202:N-Methylaspartate; D048031:JNK Mitogen-Activated Protein Kinases; D016650:Fluorescein-5-isothiocyanate