Tokuoka, H;
Goda, Y;
(2006)
Myosin light chain kinase is not a regulator of synaptic vesicle trafficking during repetitive exocytosis in cultured hippocampal neurons.
J NEUROSCI
, 26
(45)
11606 - 11614.
10.1523/JNEUROSCI.3400-06.2006.
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Abstract
The mechanism by which synaptic vesicles (SVs) are recruited to the release site is poorly understood. One candidate mechanism for trafficking of SVs is the myosin-actin motor system. Myosin activity is modulated by myosin light chain kinase (MLCK), which in turn is activated by calmodulin. Ca2+ signaling in presynaptic terminals, therefore, may serve to regulate SV mobility along actin filaments via MLCK. Previous studies in different types of synapses have supported such a hypothesis. Here, we further investigated the role of MLCK in neurotransmitter release at glutamatergic synapses in cultured hippocampal neurons by examining the effects of two MLCK inhibitors, 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine(.)HCl (ML-7) and wortmannin. Bath application of ML-7 enhanced short-term depression of EPSCs to repetitive stimulation, whereas it reduced presynaptic release probability. However, ML-7 also inhibited action potential amplitude and voltage-gated Ca2+ channel currents. These effects were not mimicked by wortmannin, suggesting that ML-7 was not specific to MLCK in hippocampal neurons. When SV exocytosis was directly triggered by a Ca2+ ionophore, calcimycin, to bypass voltage-gated Ca2+ channels, ML-7 had no effect on neurotransmitter release. Furthermore, when SV exocytosis elicited by electrical field stimulation was monitored by styryl dye, FM1-43 [N-(3-triethylammoniumpropyl)-4-(4-( dibutylamino) styryl) pyridinium dibromide], the unloading kinetics of the dye was not altered in the presence of wortmannin. These data indicate that MLCK is not a major regulator of presynaptic SV trafficking during repetitive exocytosis at hippocampal synapses.
| Type: | Article |
|---|---|
| Title: | Myosin light chain kinase is not a regulator of synaptic vesicle trafficking during repetitive exocytosis in cultured hippocampal neurons |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1523/JNEUROSCI.3400-06.2006 |
| Keywords: | synaptic vesicle recycling, exocytosis, myosin light chain kinase, ML-7, wortmannin, repetitive stimulation, RAT SYMPATHETIC NEURONS, PHOSPHATIDYLINOSITOL 3-KINASE, NEUROTRANSMITTER RELEASE, NEUROMUSCULAR-JUNCTIONS, PRESYNAPTIC FUNCTION, POOL MOBILIZATION, DROSOPHILA MUTANT, F-ACTIN, SYNAPSES, PHOSPHORYLATION |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/9612 |
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