Sang-ho Song - Academia.edu (original) (raw)

Papers by Sang-ho Song

SummarySynapsins cluster synaptic vesicles (SVs) to provide a reserve pool (RP) of SVs that maint... more SummarySynapsins cluster synaptic vesicles (SVs) to provide a reserve pool (RP) of SVs that maintains synaptic transmission during sustained activity. However, it is unknown how synapsins cluster SVs. Here we show that either liquid-liquid phase separation (LLPS) or tetramerization-dependent cross-linking can cluster SVs, depending upon whether a synapse is excitatory or inhibitory. Cell-free reconstitution revealed that both mechanisms can cluster SVs, with tetramerization bring more effective. At inhibitory synapses, perturbing synapsin-dependent LLPS impairs SV clustering and synchronization of GABA release, while perturbing synapsin tetramerization does not. At glutamatergic synapses, the opposite is true: synapsin tetramerization enhances clustering of glutamatergic SVs and mobilization of these SVs from the RP, while synapsin LLPS does not. Comparison of inhibitory and excitatory transmission during prolonged synaptic activity revealed that synapsin LLPS serves as a brake to l...

The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

─Neuronal cells to respond to submicron-scale groove structure. On the grooved structure of parti... more ─Neuronal cells to respond to submicron-scale groove structure. On the grooved structure of particular dimension, it has been reported that neuronal cells grew perpendicular to the groove direction. We used holographic photo-responsive polymer to form a submicron-scale surface relief grating structure. A sinusoidal groove pattern is built up by holographic interference of 488㎚ Ar ion laser beams. The primary hippocampal neurons cultured on the surface of the polymer film grew extending their neurites in a perpendicular orientation to the groove direction. This suggests that laser holography can be used to control the neurites orientation and growth. The holographic grating and photo-responsive polymer will raise the possibility of controlling neural network formation between living cells by light.

Encyclopedia of Signaling Molecules, 2016

Neurochemical Journal, 2014

Journal of Neuroscience Research, 2017

Previous work has demonstrated that fusion of a luciferase to an opsin, to create a luminescent o... more Previous work has demonstrated that fusion of a luciferase to an opsin, to create a luminescent opsin or luminopsin, provides a genetically encoded means of manipulating neuronal activity via both chemogenetic and optogenetic approaches. Here we have expanded and refined the versatility of luminopsin tools by fusing an alternative luciferase variant with high light emission, Gaussia luciferase mutant GLucM23, to depolarizing and hyperpolarizing channelrhodopsins with increased light sensitivity. The combination of GLucM23 with Volvox channelrhodopsin‐1 produced LMO4, while combining GLucM23 with the anion channelrhodopsin iChloC yielded iLMO4. We found efficient activation of these channelrhodopsins in the presence of the luciferase substrate, as indicated by responses measured in both single neurons and in neuronal populations of mice and rats, as well as by changes in male rat behavior during amphetamine‐induced rotations. We conclude that these new luminopsins will be useful for ...

Cellular patterning has diverse and potential applications in scientific research and engineering... more Cellular patterning has diverse and potential applications in scientific research and engineering. We used laser holographic fabrication to construct the cellular patterning. By the interference of two laser beam on the polymer micro and nanoscale grooves were generated on the photoresponsive polymer. The growth of rat hippocampal neurons were controlled with the microfabricated structure. The directions of neurites were predominant in the perpendicular direction of the grooves and the growth rates of the neurites were also stimulated. Two dimensional cellular patterning of fibroblast cells was constructed along the patterned microstructures on the polymer. These results indicate the feasibility of guiding neurons and fibroblast cells with laser holography, opening the possibility for in-situ navigation in living cells

Journal of Cell Science, 2019

PAK-interacting guanine nucleotide exchange factor (βPix) has been implicated in many actin-based... more PAK-interacting guanine nucleotide exchange factor (βPix) has been implicated in many actin-based cellular processes including spine morphogenesis in neurons. However, the molecular mechanisms by which βPix controls spine morphology remain elusive. Previously, we have reported the expression of several alternative spliced βPix isoforms in the brain. Here, we report a novel finding that the b isoform of βPix (βPix-b) mediates regulation of spine and synapse formation. We found that βPix-b, which is mainly expressed in neurons, enhances spine and synapse formation through preferential localization at spines. In neurons, glutamate treatment efficiently stimulates Rac1 GEF activity of βPix-b. The glutamate stimulation also promotes Src kinase-mediated phosphorylation of βPix-b in both AMPA receptor- and NMDA receptor-dependent manner. Tyrosine 598 (Y598) of βPix-b is identified as the major Src-mediated phosphorylation site. Finally, Y598 phosphorylation of βPix-b enhances its Rac1 GEF ...

Molecules and cells, 2015

Synapsins were the first presynaptic proteins identified and have served as the flagship of the p... more Synapsins were the first presynaptic proteins identified and have served as the flagship of the presynaptic protein field. Here we review recent studies demonstrating that different members of the synapsin family play different roles at presynaptic terminals employing different types of synaptic vesicles. The structural underpinnings for these functions are just beginning to be understood and should provide a focus for future efforts.

Frontiers in Cellular Neuroscience

We used cultured hippocampal neurons to determine the signaling pathways mediating brain-derived ... more We used cultured hippocampal neurons to determine the signaling pathways mediating brain-derived neurotrophic factor (BDNF) regulation of spontaneous glutamate and GABA release. BDNF treatment elevated calcium concentration in presynaptic terminals; this calcium signal reached a peak within 1 min and declined in the sustained presence of BDNF. This BDNF-induced transient rise in presynaptic calcium was reduced by SKF96365, indicating that BDNF causes presynaptic calcium influx via TRPC channels. BDNF treatment increased the frequency of miniature excitatory postsynaptic currents (mEPSCs). This response consisted of two components: a transient component that peaked within 1 min of initiating BDNF application and a second component that was sustained, at a lower mEPSC frequency, for the duration of BDNF application. The initial transient component was greatly reduced by removing external calcium or by treatment with SKF96365, as well as by Pyr3, a selective blocker of TRPC3 channels. In contrast, the sustained component was unaffected in these conditions but was eliminated by U0126, an inhibitor of the MAP kinase (MAPK) pathway, as well as by genetic deletion of synapsins in neurons from a synapsin triple knockout (TKO) mouse. Thus, two pathways mediate the ability of BDNF to enhance spontaneous glutamate release: the transient component arises from calcium influx through TRPC3 channels, while the sustained component is mediated by MAPK phosphorylation of synapsins. We also examined the ability of these two BDNF-dependent pathways to regulate spontaneous release of the inhibitory neurotransmitter, GABA. BDNF had no effect on the frequency of spontaneous miniature inhibitory postsynaptic currents (mIPSCs) in neurons from wild-type (WT) mice, but surprisingly did increase mIPSC frequency in synapsin TKO mice. This covert BDNF response was blocked by removal of external calcium or by treatment with SKF96365 or Pyr3, indicating that it results from calcium influx mediated by TRPC3 channels. Thus, the BDNF-activated calcium signaling pathway can also enhance spontaneous GABA release, though this effect is suppressed by synapsins under normal physiological conditions.

The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 22, 2016

Although synapsins regulate GABA release, it is unclear which synapsin isoforms are involved. We ... more Although synapsins regulate GABA release, it is unclear which synapsin isoforms are involved. We identified the synapsin isoforms that regulate GABA release via rescue experiments in cultured hippocampal neurons from synapsin I, II, and III triple knock-out (TKO) mice. In situ hybridization indicated that five different synapsin isoforms are expressed in hippocampal interneurons. Evoked IPSC amplitude was reduced in TKO neurons compared with triple wild-type neurons and was rescued by introducing any of the five synapsin isoforms. This contrasts with hippocampal glutamatergic terminals, where only synapsin IIa rescues the TKO phenotype. Deconvolution analysis indicated that the duration of GABA release was prolonged in TKO neurons and this defect in release kinetics was rescued by each synapsin isoform, aside from synapsin IIIa. Because release kinetics remained slow, whereas peak release rate was rescued, there was a 2-fold increase in GABA release in TKO neurons expressing synapsi...