Synaptotagmin VII Is Targeted to Dense-core Vesicles and Regulates Their Ca2+-dependent Exocytosis in PC12 Cells

Fukuda, Mitsunori; Kanno, Eiko; Satoh, Minoru; Saegusa, Chika; Yamamoto, Akira

doi:10.1074/jbc.m409241200

Cited by 78 publications

(102 citation statements)

References 66 publications

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“…Thus, these results demonstrate that in primary sympathetic neurons, VAMP7-containing compartments completely overlap with Lamp1-positive late endosomes/lysosomes, as shown previously in other cell types (Advani et al, 1999;Rao et al, 2004). , keratinocytes (Hakansson et al, 2005), and the neuroendocrine cell line PC12 (Fukuda et al, 2004;Wang et al, 2005). To determine whether the same occurred in primary neurons, we performed immunolocalization of Syt VII in isolated SCG neurons.…”

Section: Resultsmentioning

confidence: 89%

A Role for Synaptotagmin VII-Regulated Exocytosis of Lysosomes in Neurite Outgrowth from Primary Sympathetic Neurons

Arantes¹,

Andrews²

2006

J. Neurosci.

145

134

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Neurite outgrowth is mediated by the exocytosis of intracellular vesicles at the tips of elongating neuronal processes. The lysosomal vesicle-associated soluble N-ethylmaleimide-sensitive factor attachment protein receptor tetanus neurotoxin insensitive vesicleassociated membrane protein (TI-VAMP)/VAMP7 was previously implicated in membrane fusion events mediating neurite outgrowth, but the participation of lysosomes in this exocytic process has remained unclear. Here, we show that VAMP7 and the lysosomal glycoprotein Lamp1 extensively colocalize in vesicles present throughout the soma and neurite outgrowths of primary sympathetic neurons. Synaptotagmin VII (Syt VII), a Ca 2ϩ -sensing synaptotagmin isoform previously shown to interact with VAMP7 during lysosomal exocytosis in fibroblasts, was detected on a subset of these lysosomal glycoprotein 1 (Lamp1)/VAMP7-positive neuronal vesicles. Ionophore-stimulated exocytosis triggered exposure of the luminal domains of both Lamp1 and Syt VII at overlapping sites on the neuronal surface, indicating that the Syt VII-containing lysosomal compartments fuse with the plasma membrane in response to [Ca 2ϩ ] i elevation. To determine whether Syt VII was required for the exocytic events mediating neurite extension, we followed the development of superior cervical ganglion neurons explanted from Syt VII-deficient mice. The results revealed a marked defect in neurite outgrowth and arborization, suggesting that Ca 2ϩ -dependent, Syt VII-regulated exocytosis of late endosomes/lysosomes plays a role in the addition of new membrane to developing neurite extensions.

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Section: Resultsmentioning

confidence: 89%

A Role for Synaptotagmin VII-Regulated Exocytosis of Lysosomes in Neurite Outgrowth from Primary Sympathetic Neurons

Arantes¹,

Andrews²

2006

J. Neurosci.

145

134

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“…This protein has also been reported to play a role in the stabilisation of the fusion pore and in the choice between kiss-and-run and full fusion events, for both synaptic vesicles of PC12 and LDCV of MIN-6 cells [32,33]. In PC12 cells, SYT VII has also been implicated in the exocytosis of synaptic vesicle [19,34,35], whereas in beta cells this protein may be implicated in endocytotic traffic and insulin exocytosis [36,37]. Using specific siRNAs, we confirm the recently published data on the role of SYT VII in insulin secretion [37] and show that SYT IV also plays a significant role in the control of insulin release from INS-1E cells.…”

Section: Discussionmentioning

confidence: 98%

“…SYT IV, SYT VII and REST silencing vectors Specific small interfering RNA (siRNA) were designed as follows: for rat Syt4, the sense target sequence 5′GAAGCACAAAGT GAAAACCA3′ was deduced from the reported mouse sequence [18]; for rat Syt7 the sense sequence 5′TCAT CACCGTCAGCCTTAG3′ was selected according to a previous publication [19]; for REST, the sense sequence 5′ GGAACCTGTTGAGAAGGGA3′ was selected using the siRNA Target Finder (Ambion, Austin, TX, USA). Two complementary DNA fragments encoding the target sequence and separated from the reverse complement by a short spacer were synthesised by Microsynth (Balgach, Switzerland).…”

Section: Methodsmentioning

confidence: 99%

Functional significance of repressor element 1 silencing transcription factor (REST) target genes in pancreatic beta cells

et al. 2008

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Aims/hypothesis The expression of several neuronal genes in pancreatic beta cells is due to the absence of the transcription factor repressor element 1 (RE-1) silencing transcription factor (REST). The identification of these traits and their functional significance in beta cells has only been partly elucidated. Herein, we investigated the biological consequences of a repression of REST target genes by expressing REST in beta cells. Methods The effect of REST expression on glucose homeostasis, insulin content and release, and beta cell mass was analysed in transgenic mice selectively expressing REST in beta cells. Relevant target genes were identified in INS-1E and primary beta cells expressing REST. Results Transgenic mice featuring a beta cell-targeted expression of REST exhibited glucose intolerance and reduced beta cell mass. In primary beta cells, REST repressed several proteins of the exocytotic machinery, including synaptosomal-associated protein (SNAP) 25, synaptotagmin (SYT) IV, SYT VII, SYT IX and complexin II; it impaired first and second phases of insulin secretion. Using RNA interference in INS-1E cells, we showed that SYT IV and SYT VII were implicated in the control of insulin release.

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“…Examples include nucleobindin (Lin et al 1998), pro-PC2 (Furuta et al 1998), PC2 chaperone protein 7B2 (Marzban et al 2005), secretogranin V (Furukawa et al 1999) and reticulon. Similarly, synaptotagmin 1, which has been shown to co-localise in b cells with synaptotagmin 7 (function of which is as a vesicular Ca 2C sensor for exocytosis in endocrine cells (Fukuda et al 2004)), is downregulated approximately 1 . 7-fold in MIN-6(H), compared with MIN-6(L).…”

Section: Secretionmentioning

confidence: 99%

Phenotypic and global gene expression profile changes between low passage and high passage MIN-6 cells

O’Driscoll¹,

Gammell²,

McKiernan³

et al. 2006

Journal of Endocrinology

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The long-term potential to routinely use replacement b cells/islets as cell therapy for type 1 diabetes relies on our ability to culture such cells/islets, in vitro, while maintaining their functional status. Previous b cell studies, by ourselves and other researchers, have indicated that the glucosestimulated insulin secretion (GSIS) phenotype is relatively unstable, in long-term culture. This study aimed to investigate phenotypic and gene expression changes associated with this loss of GSIS, using the MIN-6 cell line as model. Phenotypic differences between MIN-6(L, low passage) and MIN-6(H, high passage) were determined by ELISA (assessing GSIS and cellular (pro)insulin content), proliferation assays, phase contrast light microscopy and analysis of alkaline phosphatase expression. Differential mRNA expression was investigated using microarray, bioinformatics and real-time PCR technologies. Long-term culture was found to be associated with many phenotypic changes, including changes in growth rate and cellular morphology, as well as loss of GSIS. Microarray analyses indicate expression of many mRNAs, including many involved in regulated secretion, adhesion and proliferation, to be significantly affected by passaging/ long-term culture. Loss/reduced levels, in high passage cells, of certain transcripts associated with the mature b cell, together with increased levels of neuron/glia-associated mRNAs, suggest that, with time in culture, MIN-6 cells may revert to an early (possibly multi-potential), poorly differentiated, 'precursorlike' cell type. This observation is supported by increased expression of the stem cell marker, alkaline phosphatase.

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Synaptotagmin VII Is Targeted to Dense-core Vesicles and Regulates Their Ca2+-dependent Exocytosis in PC12 Cells

Cited by 78 publications

References 66 publications

A Role for Synaptotagmin VII-Regulated Exocytosis of Lysosomes in Neurite Outgrowth from Primary Sympathetic Neurons

A Role for Synaptotagmin VII-Regulated Exocytosis of Lysosomes in Neurite Outgrowth from Primary Sympathetic Neurons

Functional significance of repressor element 1 silencing transcription factor (REST) target genes in pancreatic beta cells

Phenotypic and global gene expression profile changes between low passage and high passage MIN-6 cells

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