-
Neuron Apr 2010Synapse-specific vesicle pools have been widely characterized at central terminals. Here, we demonstrate a vesicle pool that is not confined to a synapse but spans...
Synapse-specific vesicle pools have been widely characterized at central terminals. Here, we demonstrate a vesicle pool that is not confined to a synapse but spans multiple terminals. Using fluorescence imaging, correlative electron microscopy, and modeling of vesicle dynamics, we show that some recycling pool vesicles at synapses form part of a larger vesicle "superpool." The vesicles within this superpool are highly mobile and are rapidly exchanged between terminals (turnover: approximately 4% of total pool/min), significantly changing vesicular composition at synapses over time. In acute hippocampal slices we show that the mobile vesicle pool is also a feature of native brain tissue. We also demonstrate that superpool vesicles are available to synapses during stimulation, providing an extension of the classical recycling pool. Experiments using focal BDNF application suggest the involvement of a local TrkB-receptor-dependent mechanism for synapse-specific regulation of presynaptic vesicle pools through control of vesicle release and capture to or from the extrasynaptic pool.
Topics: Animals; Cells, Cultured; Hippocampus; In Vitro Techniques; Models, Biological; Neurons; Presynaptic Terminals; Rats; Rats, Sprague-Dawley; Synaptic Vesicles
PubMed: 20399727
DOI: 10.1016/j.neuron.2010.03.020 -
Journal of Anatomy Dec 2020The seminal vesicles are the glands of male reproductive organs that produce the fluid and nutrient constituents of semen. It has been believed for a long time that the...
The seminal vesicles are the glands of male reproductive organs that produce the fluid and nutrient constituents of semen. It has been believed for a long time that the lumen of a seminal vesicle was a single-coiled tubular structure with irregular diverticula. There are several previous reports on the symmetry, differences in morphological sizes and classification of the seminal vesicles. However, a three-dimensional-coiled tubular structure is difficult to understand using a classical anatomical methodology, and hence, three-dimensional reconstruction is needed to understand the structure of the lumen. Thirty-one seminal vesicles harvested from 21 formalin-embalmed cadavers were investigated. The seminal vesicle along with the ampulla of the ductus deferens was separated, and the length and width of each seminal vesicle were measured. The vesicles were then embedded in coloured paraffin, and the resulting paraffin block was sectioned transversely and photographed at an interval of 500 μm, with the sectioned surfaces then utilized in three-dimensional reconstruction performed by 'Reconstruct' software. The mean length and width of the seminal vesicles were 39.4 mm and 13.4 mm, respectively, and the right seminal vesicle was a little larger than the one on the left. The size differed from previous reports, while the luminal structure was similar to the classification of Aboul-azm (Archives of Andrology, 3, 1979, 287-292) but differed from that of Pereira (AJR. American Journal of Roentgenology, 69, 1953, 361-379). The seminal vesicles typically comprised about 9 curls and had about 12 diverticula. The seminal vesicles resembled a skein of coral rather than comprising a single strand. These findings will help in improving the understanding of pathophysiologies of the seminal vesicles, such as recurrent inflammation of the gland.
Topics: Aged; Aged, 80 and over; Humans; Image Processing, Computer-Assisted; Imaging, Three-Dimensional; Male; Seminal Vesicles
PubMed: 33085100
DOI: 10.1111/joa.13269 -
Cells Jun 2020Cellular secretion depends on exocytosis of secretory vesicles and discharge of vesicle contents. Actin and myosin are essential for pre-fusion and post-fusion stages of... (Review)
Review
Cellular secretion depends on exocytosis of secretory vesicles and discharge of vesicle contents. Actin and myosin are essential for pre-fusion and post-fusion stages of exocytosis. Secretory vesicles depend on actin for transport to and attachment at the cell cortex during the pre-fusion phase. Actin coats on fused vesicles contribute to stabilization of large vesicles, active vesicle contraction and/or retrieval of excess membrane during the post-fusion phase. Myosin molecular motors complement the role of actin. Myosin V is required for vesicle trafficking and attachment to cortical actin. Myosin I and II members engage in local remodeling of cortical actin to allow vesicles to get access to the plasma membrane for membrane fusion. Myosins stabilize open fusion pores and contribute to anchoring and contraction of actin coats to facilitate vesicle content release. Actin and myosin function in secretion is regulated by a plethora of interacting regulatory lipids and proteins. Some of these processes have been first described in non-neuronal cells and reflect adaptations to exocytosis of large secretory vesicles and/or secretion of bulky vesicle cargoes. Here we collate the current knowledge and highlight the role of actomyosin during distinct phases of exocytosis in an attempt to identify unifying molecular mechanisms in non-neuronal secretory cells.
Topics: Actin Cytoskeleton; Actins; Animals; Exocytosis; Humans; Membrane Fusion; Myosins; Secretory Vesicles
PubMed: 32545391
DOI: 10.3390/cells9061455 -
Neuroreport Dec 2000Presynaptic plasticity mechanisms rely on modulation of the synaptic vesicle fusion machinery and the regulated mobilization of synaptic vesicles at the active zone.... (Review)
Review
Presynaptic plasticity mechanisms rely on modulation of the synaptic vesicle fusion machinery and the regulated mobilization of synaptic vesicles at the active zone. This review discusses recent evidence suggesting that the relative proportions of synaptic vesicles in the reserve and ready releasable pools is the primary determinant of synaptic transmission strength, and that transport of vesicles between these pools is mediated by cytoskeletal mechanisms. Recent efforts to identify the molecules required for regulation of the presynaptic cytoskeleton suggest that common mechanisms may exist to regulate synaptic vesicle pools in widely divergent neuronal types, ranging from synaptic modulation at the Drosophila neuromuscular junction to the synaptic plasticity required for learning and memory in the mammalian brain.
Topics: Animals; Cytoskeleton; Drosophila; Presynaptic Terminals; Synaptic Transmission; Synaptic Vesicles
PubMed: 11192639
DOI: 10.1097/00001756-200012180-00002 -
Molecular and Cellular Endocrinology Aug 2013Neuroendocrine cells contain small and large vesicles, but the functional significance of vesicle diameter is unclear. We studied unitary exocytic events of...
Neuroendocrine cells contain small and large vesicles, but the functional significance of vesicle diameter is unclear. We studied unitary exocytic events of prolactin-containing vesicles in lactotrophs by monitoring discrete steps in membrane capacitance. In the presence of sphingosine, which recruits VAMP2 for SNARE complex formation, the frequency of transient and full fusion events increased. Vesicles with larger diameters proceeded to full fusion, but smaller vesicles remained entrapped in transient exocytosis. The diameter of vesicle dense cores released by full fusion exocytosis into the extracellular space was larger than the diameter of the remaining intracellular vesicles beneath the plasma membrane. Labeling with prolactin- and VAMP2-antibodies revealed a correlation between the diameters of colocalized prolactin- and VAMP2-positive structures. It is proposed that sphingosine-mediated facilitation of regulated exocytosis is not only related to the number of SNARE complexes per vesicle but also depends on the vesicle size, which may determine the transition between transient and full fusion exocytosis.
Topics: Animals; Cell Membrane; Electric Capacitance; Exocytosis; Gene Expression; Lactotrophs; Male; Membrane Fusion; Membrane Potentials; Patch-Clamp Techniques; Prolactin; Rats; Rats, Wistar; SNARE Proteins; Secretory Vesicles; Sphingosine; Vesicle-Associated Membrane Protein 2
PubMed: 23791846
DOI: 10.1016/j.mce.2013.06.012 -
Traffic (Copenhagen, Denmark) Nov 2019In mammals, 15 to 20 kinesins are thought to mediate vesicle transport. Little is known about the identity of vesicles moved by each kinesin or the functional...
In mammals, 15 to 20 kinesins are thought to mediate vesicle transport. Little is known about the identity of vesicles moved by each kinesin or the functional significance of such diversity. To characterize the transport mediated by different kinesins, we developed a novel strategy to visualize vesicle-bound kinesins in living cells. We applied this method to cultured neurons and systematically determined the localization and transport parameters of vesicles labeled by different members of the Kinesin-1, -2, and -3 families. We observed vesicle labeling with nearly all kinesins. Only six kinesins bound vesicles that undergo long-range transport in neurons. Of these, three had an axonal bias (KIF5B, KIF5C and KIF13B), two were unbiased (KIF1A and KIF1Bβ), and one transported only in dendrites (KIF13A). Overall, the trafficking of vesicle-bound kinesins to axons or dendrites did not correspond to their motor domain preference, suggesting that on-vesicle regulation is crucial for kinesin targeting. Surprisingly, several kinesins were associated with populations of somatodendritic vesicles that underwent little long-range transport. This assay should be broadly applicable for investigating kinesin function in many cell types.
Topics: Animals; Axons; Cells, Cultured; Dendrites; Kinesins; Neurons; Organelles; Protein Transport; Rats; Synaptic Vesicles
PubMed: 31461551
DOI: 10.1111/tra.12692 -
The Journal of Physiology Aug 2019We used presynaptic capacitance measurements at the hippocampal mossy fibre terminal at room temperature to measure Ca-dependence of exo- and endocytotic kinetics. The...
KEY POINTS
We used presynaptic capacitance measurements at the hippocampal mossy fibre terminal at room temperature to measure Ca-dependence of exo- and endocytotic kinetics. The readily releasable pool (RRP) of synaptic vesicles was released with a time constant of 30-40 ms and was sensitive to Ca buffers, BAPTA and EGTA. Our data suggest that recruitment of the vesicles to the RRP was Ca-insensitive and had a time constant of 1 s. In addition to the RRP, the reserve pool of vesicles, which had a similar size to RRP, was depleted during repetitive stimulation. Our data suggest that synaptic vesicle endocytosis was also Ca-insensitive.
ABSTRACT
Hippocampal mossy fibre terminals comprise one of the cortical terminals, which are sufficiently large to be accessible by patch clamp recordings. To measure Ca-dependence of exo- and endocytotic kinetics quantitatively, we applied presynaptic capacitance measurements to the mossy fibre terminal at room temperature. The time course of synaptic vesicle fusion was slow, with a time constant of tens of milliseconds, and was sensitive to Ca buffers EGTA and BAPTA, suggesting a loose coupling between Ca channels and synaptic vesicles. The size of the readily-releasable pool (RRP) of synaptic vesicles was relatively insensitive to Ca buffers. Once the RRP was depleted, it was recovered by a single exponential with a time constant of ∼1 s independent of the presence of Ca buffers, suggesting Ca independent vesicle replenishment. In addition to the RRP, the reserve pool of vesicles was released slowly during repetitive stimulation. Endocytosis was also insensitive to Ca buffers and had a slow time course, excluding the involvement of rapid vesicle cycling in vesicle replenishment. Although mossy fibre terminals are known to have various forms of Ca-dependent plasticity, some features of vesicle dynamics are robust and Ca-insensitive.
Topics: Animals; Calcium; Endocytosis; Exocytosis; Female; Male; Mossy Fibers, Hippocampal; Patch-Clamp Techniques; Rats, Wistar; Synaptic Vesicles
PubMed: 31294821
DOI: 10.1113/JP278040 -
Proceedings of the National Academy of... Apr 2015Vesicle recycling is pivotal for maintaining reliable synaptic signaling, but its basic properties remain poorly understood. Here, we developed an approach to...
Vesicle recycling is pivotal for maintaining reliable synaptic signaling, but its basic properties remain poorly understood. Here, we developed an approach to quantitatively analyze the kinetics of vesicle recycling with exquisite signal and temporal resolution at the calyx of Held synapse. The combination of this electrophysiological approach with electron microscopy revealed that ∼80% of vesicles (∼270,000 out of ∼330,000) in the nerve terminal are involved in recycling. Under sustained stimulation, recycled vesicles start to be reused in tens of seconds when ∼47% of the preserved vesicles in the recycling pool (RP) are depleted. The heterogeneity of vesicle recycling as well as two kinetic components of RP depletion revealed the existence of a replenishable pool of vesicles before the priming stage and led to a realistic kinetic model that assesses the size of the subpools of the RP. Thus, our study quantified the kinetics of vesicle recycling and kinetically dissected the whole vesicle pool in the calyceal terminal into the readily releasable pool (∼0.6%), the readily priming pool (∼46%), the premature pool (∼33%), and the resting pool (∼20%).
Topics: Algorithms; Animals; Auditory Pathways; Electric Stimulation; Excitatory Postsynaptic Potentials; Kinetics; Mice, Inbred C57BL; Microscopy, Electron, Transmission; Microscopy, Fluorescence, Multiphoton; Models, Neurological; Presynaptic Terminals; Sensorimotor Cortex; Synapses; Synaptic Transmission; Synaptic Vesicles
PubMed: 25825725
DOI: 10.1073/pnas.1424597112 -
The Journal of Neuroscience : the... Dec 2012Sustained neuronal communication relies on the coordinated activity of multiple proteins that regulate synaptic vesicle biogenesis and cycling within the presynaptic...
Sustained neuronal communication relies on the coordinated activity of multiple proteins that regulate synaptic vesicle biogenesis and cycling within the presynaptic terminal. Synaptogyrin and synaptophysin are conserved MARVEL domain-containing transmembrane proteins that are among the most abundant synaptic vesicle constituents, although their role in the synaptic vesicle cycle has remained elusive. To further investigate the function of these proteins, we generated and characterized a synaptogyrin (gyr)-null mutant in Drosophila, whose genome encodes a single synaptogyrin isoform and lacks a synaptophysin homolog. We demonstrate that Drosophila synaptogyrin plays a modulatory role in synaptic vesicle biogenesis at larval neuromuscular junctions. Drosophila lacking synaptogyrin are viable and fertile and have no overt deficits in motor function. However, ultrastructural analysis of gyr larvae revealed increased synaptic vesicle diameter and enhanced variability in the size of synaptic vesicles. In addition, the resolution of endocytic cisternae into synaptic vesicles in response to strong stimulation is defective in gyr mutants. Electrophysiological analysis demonstrated an increase in quantal size and a concomitant decrease in quantal content, suggesting functional consequences for transmission caused by the loss of synaptogyrin. Furthermore, high-frequency stimulation resulted in increased facilitation and a delay in recovery from synaptic depression, indicating that synaptic vesicle exo-endocytosis is abnormally regulated during intense stimulation conditions. These results suggest that synaptogyrin modulates the synaptic vesicle exo-endocytic cycle and is required for the proper biogenesis of synaptic vesicles at nerve terminals.
Topics: Amino Acid Sequence; Animals; Animals, Genetically Modified; Blotting, Western; Drosophila; Immunohistochemistry; Microscopy, Electron, Transmission; Molecular Sequence Data; Mutation; Neuromuscular Junction; Patch-Clamp Techniques; Synaptic Vesicles; Synaptogyrins
PubMed: 23238721
DOI: 10.1523/JNEUROSCI.2668-12.2012 -
Asian Journal of Surgery Jul 2022
Topics: Cysts; Genital Diseases, Male; Hand; Humans; Kidney; Male; Seminal Vesicles; Upper Extremity
PubMed: 35304051
DOI: 10.1016/j.asjsur.2022.02.057