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CAPS and syntaxin dock dense core vesicles to the plasma membrane in neurons.

Hammarlund M, Watanabe S, Schuske K, Jorgensen EM - J. Cell Biol. (2008)

Bottom Line: In Caenorhabditis elegans motor neurons, dense core vesicles dock at the plasma membrane but are excluded from active zones at synapses.Both the CAPS and UNC-13 docking pathways converge on syntaxin, a component of the SNARE (soluble N-ethyl-maleimide-sensitive fusion protein attachment receptor) complex.CAPS function in dense core vesicle docking parallels UNC-13 in synaptic vesicle docking, which suggests that these related proteins act similarly to promote docking of independent vesicle populations.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.

ABSTRACT
Docking to the plasma membrane prepares vesicles for rapid release. Here, we describe a mechanism for dense core vesicle docking in neurons. In Caenorhabditis elegans motor neurons, dense core vesicles dock at the plasma membrane but are excluded from active zones at synapses. We have found that the calcium-activated protein for secretion (CAPS) protein is required for dense core vesicle docking but not synaptic vesicle docking. In contrast, we see that UNC-13, a docking factor for synaptic vesicles, is not essential for dense core vesicle docking. Both the CAPS and UNC-13 docking pathways converge on syntaxin, a component of the SNARE (soluble N-ethyl-maleimide-sensitive fusion protein attachment receptor) complex. Overexpression of open syntaxin can bypass the requirement for CAPS in dense core vesicle docking. Thus, CAPS likely promotes the open state of syntaxin, which then docks dense core vesicles. CAPS function in dense core vesicle docking parallels UNC-13 in synaptic vesicle docking, which suggests that these related proteins act similarly to promote docking of independent vesicle populations.

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Dense core vesicles dock at the neuronal plasma membrane. (A) Electron micrograph of a portion of the ventral nerve cord from a C. elegans adult hermaphrodite. The blue arrow indicates a docked synaptic vesicle and the red arrow indicates a docked dense core vesicle. Bar, 200 nm. (B) A schematic depiction of the micrograph in A with some features indicated. (C) All dense core vesicle diameters displayed as a histogram (left) and a semi-log cumulative probability distribution (right). n = 990.
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fig1: Dense core vesicles dock at the neuronal plasma membrane. (A) Electron micrograph of a portion of the ventral nerve cord from a C. elegans adult hermaphrodite. The blue arrow indicates a docked synaptic vesicle and the red arrow indicates a docked dense core vesicle. Bar, 200 nm. (B) A schematic depiction of the micrograph in A with some features indicated. (C) All dense core vesicle diameters displayed as a histogram (left) and a semi-log cumulative probability distribution (right). n = 990.

Mentions: To compare the distribution and molecular requirements for docking of dense core and synaptic vesicles, we analyzed the ventral cord motor neurons, which contain and release both vesicle types. Dense core vesicles can be distinguished from synaptic vesicles by their electron-dense appearance (Fig. 1, A and B) and are observed in both acetylcholine and γ-aminobutyric acid (GABA) neurons. These vesicles have a mean diameter of 42.5 nm and their range of diameters appears to be normally distributed around this single mean, which suggests that these vesicles are all of the same type (Fig. 1 C). Some of these vesicles are docked, appearing to directly contact the plasma membrane (Fig. 1, A and B). The fraction of dense core vesicles docked (4.5%) is roughly similar to that of synaptic vesicles (9.8%).


CAPS and syntaxin dock dense core vesicles to the plasma membrane in neurons.

Hammarlund M, Watanabe S, Schuske K, Jorgensen EM - J. Cell Biol. (2008)

Dense core vesicles dock at the neuronal plasma membrane. (A) Electron micrograph of a portion of the ventral nerve cord from a C. elegans adult hermaphrodite. The blue arrow indicates a docked synaptic vesicle and the red arrow indicates a docked dense core vesicle. Bar, 200 nm. (B) A schematic depiction of the micrograph in A with some features indicated. (C) All dense core vesicle diameters displayed as a histogram (left) and a semi-log cumulative probability distribution (right). n = 990.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2234227&req=5

fig1: Dense core vesicles dock at the neuronal plasma membrane. (A) Electron micrograph of a portion of the ventral nerve cord from a C. elegans adult hermaphrodite. The blue arrow indicates a docked synaptic vesicle and the red arrow indicates a docked dense core vesicle. Bar, 200 nm. (B) A schematic depiction of the micrograph in A with some features indicated. (C) All dense core vesicle diameters displayed as a histogram (left) and a semi-log cumulative probability distribution (right). n = 990.
Mentions: To compare the distribution and molecular requirements for docking of dense core and synaptic vesicles, we analyzed the ventral cord motor neurons, which contain and release both vesicle types. Dense core vesicles can be distinguished from synaptic vesicles by their electron-dense appearance (Fig. 1, A and B) and are observed in both acetylcholine and γ-aminobutyric acid (GABA) neurons. These vesicles have a mean diameter of 42.5 nm and their range of diameters appears to be normally distributed around this single mean, which suggests that these vesicles are all of the same type (Fig. 1 C). Some of these vesicles are docked, appearing to directly contact the plasma membrane (Fig. 1, A and B). The fraction of dense core vesicles docked (4.5%) is roughly similar to that of synaptic vesicles (9.8%).

Bottom Line: In Caenorhabditis elegans motor neurons, dense core vesicles dock at the plasma membrane but are excluded from active zones at synapses.Both the CAPS and UNC-13 docking pathways converge on syntaxin, a component of the SNARE (soluble N-ethyl-maleimide-sensitive fusion protein attachment receptor) complex.CAPS function in dense core vesicle docking parallels UNC-13 in synaptic vesicle docking, which suggests that these related proteins act similarly to promote docking of independent vesicle populations.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.

ABSTRACT
Docking to the plasma membrane prepares vesicles for rapid release. Here, we describe a mechanism for dense core vesicle docking in neurons. In Caenorhabditis elegans motor neurons, dense core vesicles dock at the plasma membrane but are excluded from active zones at synapses. We have found that the calcium-activated protein for secretion (CAPS) protein is required for dense core vesicle docking but not synaptic vesicle docking. In contrast, we see that UNC-13, a docking factor for synaptic vesicles, is not essential for dense core vesicle docking. Both the CAPS and UNC-13 docking pathways converge on syntaxin, a component of the SNARE (soluble N-ethyl-maleimide-sensitive fusion protein attachment receptor) complex. Overexpression of open syntaxin can bypass the requirement for CAPS in dense core vesicle docking. Thus, CAPS likely promotes the open state of syntaxin, which then docks dense core vesicles. CAPS function in dense core vesicle docking parallels UNC-13 in synaptic vesicle docking, which suggests that these related proteins act similarly to promote docking of independent vesicle populations.

Show MeSH
Related in: MedlinePlus