Transforming growth factor beta1 alters synapsin distribution and modulates synaptic depression in Aplysia.
Transforming growth factor beta1 (TGF-beta1) induces long-term synaptic facilitation and long-term increases in excitability in Aplysia. Here we report that this growth factor has acute effects as well. Treatment of pleural-pedal ganglia with TGF-beta1 for 5 min activated mitogen-activated protein kinase (MAPK) and stimulated the phosphorylation of synapsin in a MAPK-dependent manner. This phosphorylation appeared to modulate synapsin distribution in cultured sensory neurons. Control neurons exhibited a punctate distribution of synapsin along neurites, which appeared to represent high concentration aggregates of synapsin. TGF-beta1-treated sensory neurons showed a significant reduction in the number of these puncta, an effect that was blocked by the MAP/ERK kinase inhibitor U0126. The functional consequence of TGF-beta1 was tested by examining its effects on synaptic transmission at the sensorimotor synapse. Application of TGF-beta1 reduced the magnitude of synaptic depression. This effect was dependent on MAPK, consistent with the hypothesis that TGF-1 mobilizes synaptic vesicles through the phosphorylation of synapsin.
Chin
J
J
Department of Neurobiology and Anatomy, W. M. Keck Center for the Neurobiology of Learning and Memory, University of Texas-Houston Medical School, Houston, Texas 77030, USA.
Angers
A
A
Cleary
L J
LJ
Eskin
A
A
Byrne
J H
JH
D000818:Animals; D001048:Aplysia; D002070:Butadienes / Q000494:pharmacology; D002478:Cells, Cultured; D004558:Electric Stimulation; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009046:Motor Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects* / Q000502:physiology; D016501:Neurites / Q000378:metabolism; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D013569:Synapses / Q000187:drug effects* / Q000378:metabolism*; D016704:Synapsins / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology; D013572:Synaptic Vesicles / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1
D002070:Butadienes; D004791:Enzyme Inhibitors; D046911:Macromolecular Substances; D009570:Nitriles; D016704:Synapsins; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; C113580:U 0126; D020928:Mitogen-Activated Protein Kinases