Neuronal SNARE proteins mediate neurotransmitter release at the synapse by facilitating the fusion of vesicles to the presynaptic plasma membrane. Cognate v-SNAREs and t-SNAREs from the vesicle and the plasma membrane, respectively, zip up and bring about the apposition of two membranes attached at the Cterminal ends. Here, we demonstrate that SNARE zippering can be modulated in the midways by wedging with small hydrophobic molecules. Myricetin, which intercalated into the hydrophobic inner core near the middle of the SNARE complex, stopped SNARE zippering in motion and accumulated the trans-complex, where the N-terminal region of v-SNARE VAMP2 is in the coiled coil with the frayed C-terminal region. Delphinidin and cyanidin inhibited N-terminal nucleation of SNARE zippering. Neuronal SNARE complex in PC12 cells showed the same pattern of vulnerability to small hydrophobic molecules. We propose that the half-zipped trans-SNARE complex is a crucial intermediate waiting for a calcium trigger that leads to fusion pore opening.polyphenol | hemifusion | neurotransmission | neuron N eurotransmitter release at the synapse, which serves as the brain's major form of cell-cell communication, requires the fusion of synaptic vesicles with the presynaptic plasma membrane. Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins mediate this synaptic fusion event (1-5), and the formation of a four-helical bundle (6-8) is believed to generate the force required for fusion. A zipper model has been proposed for SNARE complex formation, initiating assembly at the N-terminal region and zipping toward the C-terminal membrane-proximal region (6-9). To account for fast neuroexocytosis, the SNAREs in primed readily releasable vesicles have been proposed as being partially zipped in the trans-configuration bridging the two membranes.Although the structure of the fully assembled cis-SNARE complex, which is believed to represent the postfusion state, has been determined (10), the structure of the trans-complex is poorly understood and is purely imaginary, most likely because of its inherently transient nature. Precisely linking the degrees of SNARE zippering to specific stages of membrane fusion seems to be prerequisite for determining the structure of the trans-complex and for providing answers to the questions of how fast fusion is controlled in neurons and how the trans-complexes set up the readily releasable vesicles with other regulatory proteins.Here, we show that certain small hydrophobic molecules (SHM) enable layer-by-layer control of SNARE zippering by wedging into various points of the SNARE zipper. SNAREmediated membrane fusion is dissected via this wedge-like action of SHMs. Analysis of the captured replication fork-like structure allowed us to understand the basic architecture of the putative trans-complex. Results SNARE-Driven Membrane Fusion Can Be Controlled by SHMs withDifferent Modes of Action. As an initial step to examine the feasibility of whether SHM works as a wedge for the SNARE zipp...

FDS and C29 alleviates the decrease in cognitive function and inhibited amyloid-β expression in Tg mice by regulating microglia activation and gut microbiota composition.

Lactobacillus plantarum C29-fermented defatted soybean (FDS), which contains soyasaponins such as soyasaponin I (SI) and soyasapogenol B (SB) and isoflavones such as genistin (GE) and genistein (GT), attenuated memory impairment in mice. Moreover, in the preliminary study, FDS and its soyasaponins and isoflavones significantly inhibited NF-κB activation in LPS-stimulated microglial BV2 cells. Therefore, we examined the effects of FDS and its constituents SI, SB, GT, and GE on LPS-induced memory impairment in mice. Oral administration of FDS (80 mg/kg), which has higher concentrations of SB and GE than DS, recovered LPS-impaired cognitive function in Y-maze (55.1 ± 3.5%) and passive avoidance tasks (50.9 ± 19.2 s) to 129.2% (74.1 ± 3.5%) and 114.2% (290.0 ± 22.4 s) of normal mice, respectively (P < 0.05). SB and GE (10 μM) also more potently attenuated LPS-impaired cognitive behavior than SI and GT, respectively. SB (10 mg/kg) was the most effective: treatment recovered LPS-impaired spontaneous alternation and latency time to 105.7% and 126.8% of normal control mice, respectively (P < 0.05). SB and GE significantly increased BDNF expression and CREB phosphorylation in LPS-treated mice and corticosterone-stimulated SH-SY5Y cells. Furthermore, SB and GE (10 μM) also significantly inhibited NF-κB activation in LPS-treated mice. These findings suggested that FDS and its constituent soyasaponins and isoflavones may attenuate memory impairment by the regulation of NF-κB-mediated BDNF expression.