Expression of a conserved cell-type-specific protein in nerve terminals coincides with synaptogenesis.

Catsicas, Stefan; Larhammar, Dan; Blomqvist, Anders; Sanna, Pietro Paolo; Milner, Robert J.; Wilson, Michael C.

doi:10.1073/pnas.88.3.785

Cited by 103 publications

(72 citation statements)

References 35 publications

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“…Replacing any one of the Cys with Ser led to reduction in the overall incorporation of palmitate ranging from 58 to 90% (Table 2). SNAP-25 sequences from mouse (Oyler et al, 1989), chicken (Catsicas et al, 1991), goldfish , and Drosophila and Torpedd all contain four to five…”

Section: Palmitoylation Is Required For Membrane Association Of Snap25mentioning

confidence: 99%

“…It has been shown to interact with both syntaxin and synaptobrevin by in vitro binding assays (Chapman et al, 1994; Pevsner et al, 1994; McMahon and Sudhof, 1995). Analysis of cDNA clones of SNAP-25 from mouse (Oyler et al, 1989), chicken (Catsicas et al, 1991), and Drosophila and Torpedo showed that the protein is highly conserved through evolution and is expressed specifically in the nervous systems. SNAP-25 plays an important role in synaptic vesicle docking/fusion.…”

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confidence: 99%

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Characterization of the Palmitoylation Domain of SNAP‐25

Lane

Liu

1997

Journal of Neurochemistry

111

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SNAP-25 (synaptosomal associated protein of 25 kDa) is a neural specific protein that has been implicated in the synaptic vesicle docking and fusion process. It is tightly associated with membranes, and it is one of the major palmitoylated proteins found in neurons. The functional role of palmitoylation for SNAP-25 is unclear.In this report, we show that the palmitate of SNAP-25 is rapidly turned over in Pci 2 cells, with a half-life of -~3h, and the half-life for the protein is 8 h. Mutation of Cys to Ser at positions 85, 88, 90, and 92 reduced the palmitoylation to 9, 21, 42, and 35% of the wild-type protein, respectively. Additional mutations of either Cys 85'88 or Cys9092 nearly abolished palmitoylation of the protein. A similar effect on membrane binding for the mutant SNAP-25 was observed, which correlated with the degree of palmitoylation. These results suggest that all four cys residues are involved in palmitoylation and that membrane association of SNAP-25 may be regulated through dynamic palmitoylation. Key Words: Synaptic proteins-SNAP-25-Palmitoylation-Membrane association-Mutagenesis-Protein turnover. J. Neurochem. 69, 1864Neurochem. 69, -1869Neurochem. 69, (1997.The synaptosomal associated protein of 25 kDa, SNAP-25, is a member ofthe synaptic vesicle docking! fusion complex that includes syntaxin, synaptobrevin (VAMP), and synaptotagmin (for reviews, see Bennett and Scheller, 1994;Ferro-Novick and Jahn, 1994;Rothman and Warren, 1994; Sudhof, 1995). It has been shown to interact with both syntaxin and synaptobrevin by in vitro binding assays (Chapman et al., 1994; Pevsner et al., 1994; McMahon and Sudhof, 1995). Analysis of cDNA clones of SNAP-25 from mouse (Oyler et al., 1989), chicken (Catsicas et al., 1991), and Drosophila and Torpedo showed that the protein is highly conserved through evolution and is expressed specifically in the nervous systems. SNAP-25 plays an important role in synaptic vesicle docking/fusion. Specific cleavage of the protein by botulinum neurotoxins A and E blocks neurotransmitter release at neuromuscular junctions (Biasi et al., 1993;Schiavo et a!., 1993;Binz et al., 1994). More recently, SNAP-25 homologues from yeast and nonneuronal tissues were cloned, which showed high degrees of homology in the important functional domains (Brennwald et al., 1994;Ravichandran et al., 1996). These results strongly suggest that SNAP-25 and its homologues play fundamental roles in vesicular transport.SNAP-25 is localized primarily to the membrane fractions in both developing and adult brains (Oyier et a!., 1989). It is one of the major palmitoylated proteins found in neurons (Hess et a!., 1992), and this posttranslational modification may play an important role in modulating the physiological functions of the protein. Deletion of a 12-amino acid sequence containing the four Cys residues of SNAP-25 abolished palmitoylation and membrane association of the protein, suggesting that paimitoylation may be required for membrane association (Veit et al., 1996). Two SNAP-25 isoform...

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Section: Palmitoylation Is Required For Membrane Association Of Snap25mentioning

confidence: 99%

mentioning

confidence: 99%

Characterization of the Palmitoylation Domain of SNAP‐25

Lane

Liu

1997

Journal of Neurochemistry

111

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“…Immunocytochemical studies indicated that, unlike synapsin I and synaptophysin, SNAP-25 was expressed and localized in the presynaptic regions of specific, but diverse, populations of central nervous system neurons (7,8). Although the exact function of SNAP-25 is unknown, its pattern of localization and high degree of conservation between various vertebrate species and an invertebrate, Drosophila (9,23), suggest an important role in synaptic function. To better understand the sequence of events leading to the adult pattern of SNAP-25 mRNA and protein expression, a series of investigations was performed on developing rat brain.…”

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confidence: 99%

Developmental expression of the 25-kDa synaptosomal-associated protein (SNAP-25) in rat brain.

Oyler

Polli

Wilson

et al. 1991

Proc. Natl. Acad. Sci. U.S.A.

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112

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The developmental expression and subcellular distribution of the neuron-specific 25-kDa synaptosomal protein (SNAP-25) were investigated by using Northern (RNA) blots, immunoblots, and immunocytochemistry. Both SNAP-25 protein and mRNA were present at low levels in embryonic day 15 rat brain, and levels of both increased during early postnatal maturation. Developmental immunoblots with antipeptide antisera demonstrated that a 25-kDa peptide was the major isoform in brain, and this form increased steadily from embryonic day 15 through adulthood. A second 27-kDa immunoreactive isoform was present in brain only during early development. Immunoblots of two-dimensional SDS/polyacrylamide gels revealed the presence of a predominant 25-kDa isoform of SNAP-25 in adult brain. Immunocytochemical studies indicated that as immunoreactivity for SNAP-25 increased during development, the cellular localization of SNAP-25 immunoreactivity concomitantly shifted from axons and cell bodies to presynaptic terminals. These data suggest that the SNAP-25 protein shifts in subcellular localization during development and may play a role in the establishment and stabilization of specific presynaptic terminals in brain.One goal in neurobiology is to understand the molecular mechanisms that regulate the synthesis, storage, release, and reuptake of neurotransmitters (1). Presynaptic regions of neurons may show considerable plasticity during development and after injury (2), suggesting that molecular mechanisms are present that allow adaptation. Thus, by carefully analyzing the developmental changes in specific molecular components within the presynaptic terminal, a better understanding of the function of developing and regenerating synapses may be elucidated.Recent approaches to understanding the function of the presynaptic region have focused on the isolation and characterization of proteins enriched in presynaptic terminals. Synapsin I (3), synaptophysin (4), and vesicle-associated membrane protein (5) are examples of presynaptic proteins present in most presynaptic neurons; such proteins are used as markers of presynaptic terminals. These proteins presumably modulate the interactions of synaptic vesicles with other proteins in the active zone of the synapse, leading to regulation of vesicle mobility, release, and retrieval. For example, calcium-mediated phosphorylation of synapsin I via calmodulin-dependent protein kinases I and II may initiate movement and release of synaptic vesicle contents (6).We have recently isolated and characterized cDNAs encoding a 25-kDa synaptosomal-associated protein termed SNAP-25 (7). This hydrophilic protein is composed of 206 residues and is tightly associated with presynaptic membranes. Immunocytochemical studies indicated that, unlike synapsin I and synaptophysin, SNAP-25 was expressed and localized in the presynaptic regions of specific, but diverse, populations of central nervous system neurons (7,8). Although the exact function of SNAP-25 is unknown, its pattern of localization and high degree...

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“…During development, the expression of SNAP-25 correlates with synaptogenesis and neuronal maturation (15). In the adult nervous system, SNAP-25 appears localized to presynaptic terminals (11,16), where it is conveyed by fast axonal transport (17,18).…”

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confidence: 99%

Differential expression of SNAP-25 protein isoforms during divergent vesicle fusion events of neural development.

Bark

Hahn

Ryabinin

et al. 1995

Proc. Natl. Acad. Sci. U.S.A.

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217

230

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The presynaptic plasma membrane protein SNAP-25 (synaptosome-associated protein of 25 kDa) has been implicated as one of several neural-specific components that direct constitutive fusion mechanisms to the regulated vesicle trafficking and exocytosis of neurotransmitter release.There exist two alternatively spliced isoforms of a and b, which differ in a putative membrane-interacting domain. We show that these two isoforms have distinct quantitative and anatomical patterns of expression during brain development, in neurons, and in neuroendocrine cells and that the proteins localize differently in neurites of transfected PC12 pheochromocytoma cells. These findings indicate that alternative isoforms of SNAP-25 may play distinct roles in vesicular fusion events required for membrane addition during axonal outgrowth and for release of neuromodulatory peptides and neurotransmitters.In the nervous system, the regulated release of neurotransmitters and neuromodulatory peptides and the addition of proteins and other constituents required for neurite outgrowth proceed through intracellular trafficking and fusion of vesicles at the plasma membrane (for review, see refs. 1-4). This regulated fusion of donor vesicle and acceptor (target) membranes is likely mediated by the same ubiquitious ATPdependent machinery, composed of soluble N-ethylmaleimide-sensitive factor (NSF) and NSF-associated proteins (SNAPs), that is utilized in constitutive pathways of all eukaryotic cells (5). To provide specificity for the fusion process, distinct sets of related proteins have been postulated to serve as membrane receptors, or SNAREs (6). These enable correct recognition between vesicle and target membranes at different intracellular compartments, and they engage the general fusion machinery. It is likely that specific SNAREs, together with additional cell-specific auxiliary proteins, are critical for the specialized sorting, targeting, and final recycling of vesicles which are required for the Ca2+-triggered release of neurotransmitter and modulatory peptides unique to neurons and neuroendocrine cells (7-9). Although evidence suggests that membrane addition to the expanding plasmalemma of axonal growth cones is Ca2+ dependent (10), it is thought that there are independent vesicle-targeting and fusion mechanisms that chiefly support either axon outgrowth or neurotransmitter release. Recent studies do suggest, however, that at least one of the SNAREs, SNAP-25, is a key player in membrane fusion events of both developing and mature neurons.The presynaptic nerve terminal protein SNAP-25 (synaptosome-associated protein of 25 kDa; ref. 11) has been identified as a plasma membrane protein that together with syntaxin and the synaptic vesicle proteins VAMP/synaptobrevin and synaptotagmin are thought to constitute an initial SNARE docking complex for regulated exocytosis (5, 12, 13). After docking, this complex can incorporate into a 20S fusion parThe publication costs of this article were defrayed in part by page charge payment. This a...

show abstract

Expression of a conserved cell-type-specific protein in nerve terminals coincides with synaptogenesis.

Cited by 103 publications

References 35 publications

Characterization of the Palmitoylation Domain of SNAP‐25

Characterization of the Palmitoylation Domain of SNAP‐25

Developmental expression of the 25-kDa synaptosomal-associated protein (SNAP-25) in rat brain.

Differential expression of SNAP-25 protein isoforms during divergent vesicle fusion events of neural development.

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