Publications by authors named "Anna Kadkova"

SNAP25 is one of three neuronal SNAREs driving synaptic vesicle exocytosis. We studied three mutations in SNAP25 that cause epileptic encephalopathy: V48F, and D166Y in the synaptotagmin-1 (Syt1)-binding interface, and I67N, which destabilizes the SNARE complex. All three mutations reduced Syt1-dependent vesicle docking to SNARE-carrying liposomes and Ca-stimulated membrane fusion in vitro and when expressed in mouse hippocampal neurons.

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With the increasing popularity of cryo-electron tomography (cryo-ET) in recent years, the quest to establish a method for growing primary neurons directly on electron microscopy grids (EM grids) has been ongoing. Here we describe a straightforward way to establish a mature neuronal network on EM grids, which includes formation of synaptic contacts. These synapses were thin enough to allow for direct visualization of small filaments such as SNARE proteins tethering the synaptic vesicle (SV) to the active zone plasma membrane on a Titan Krios without prior focused ion-beam milling.

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Article Synopsis
  • Researchers used cryo-electron tomography to examine synaptic vesicle fusion with the plasma membrane after stimulation, providing a clearer view of the intermediate steps involved.* -
  • The study identified two key stages during fusion: early fusion, where membrane curvature changes establish contact, and late fusion, characterized by the opening of the fusion pore and vesicle collapse.* -
  • Mutations in SNAP-25 affected the formation of tethers between synaptic vesicles and the plasma membrane, indicating that stimulation influences the morphological changes and functional transitions of synaptic vesicles.*
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N-methyl-D-aspartate receptors (NMDARs) play an essential role in excitatory neurotransmission in the mammalian brain, and their physiological importance is underscored by the large number of pathogenic mutations that have been identified in the receptor's GluN subunits and associated with a wide range of diseases and disorders. Here, we characterized the functional and pharmacological effects of the pathogenic N650K variant in the GluN1 subunit, which is associated with developmental delay and seizures. Our microscopy experiments showed that when expressed in HEK293 cells (from ATCC®), the GluN1-N650K subunit increases the surface expression of both GluN1/GluN2A and GluN1/GluN2B receptors, but not GluN1/GluN3A receptors, consistent with increased surface expression of the GluN1-N650K subunit expressed in hippocampal neurons (from embryonic day 18 of Wistar rats of both sexes).

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The transient receptor potential ankyrin 1 (TRPA1) channel is a polymodal sensor of environmental irritant compounds, endogenous proalgesic agents, and cold. Upon activation, TRPA1 channels increase cellular calcium levels via direct permeation and trigger signaling pathways that hydrolyze phosphatidylinositol-4,5-bisphosphate (PIP ) in the inner membrane leaflet. Our objective was to determine the extent to which a putative PIP -interaction site (Y1006-Q1031) is involved in TRPA1 regulation.

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Information transfer across CNS synapses depends on the very low basal vesicle fusion rate and the ability to rapidly upregulate that rate upon Ca influx. We show that local electrostatic repulsion participates in creating an energy barrier, which limits spontaneous synaptic transmission. The barrier amplitude is increased by negative charges and decreased by positive charges on the SNARE-complex surface.

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SNARE-complexes drive the fusion of membrane-bound vesicles with target membranes or with each other (homotypic fusion). The SNARE-proteins are subdivided into Q, Q, Q and R-SNAREs depending on their position in the four-helical SNARE-bundle. Here, we review the SNAP-25 protein sub-family, which includes both the Q and Q SNARE-domains within a single protein.

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Transient receptor potential ankyrin 1 (TRPA1) is a temperature-sensitive ion channel activated by various pungent and irritant compounds that can produce pain in humans. Its activation involves an allosteric mechanism whereby electrophilic agonists evoke interactions within cytosolic domains and open the channel pore through an integrated nexus formed by intracellular membrane proximal regions that are densely packed beneath the lower segment of the S1-S4 sensor domain. Studies indicate that this part of the channel may contain residues that form a water-accessible cavity that undergoes changes in solvation during channel gating.

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Exposure to repetitive low-frequency electromagnetic field (LF-EMF) shows promise as a non-invasive approach to treat various sensory and neurological disorders. Despite considerable progress in the development of modern stimulation devices, there is a limited understanding of the mechanisms underlying their biological effects and potential targets at the cellular level. A significant impact of electromagnetic field on voltage-gated calcium channels and downstream signalling pathways has been convincingly demonstrated in many distinct cell types.

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