Presence of syntaxin 1A in secretory granules of chromaffin cells and interaction with chromogranins A and B

Yoo, Seung Hyun; You, Soon Hee; Huh, Yang Hoon

doi:10.1016/j.febslet.2004.11.079

Cited by 12 publications

(7 citation statements)

References 40 publications

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“…It is highly likely that this Ca 2+ would play key roles in initiating the exocytotic processes by the secretory granules and to a certain extent by synaptic-like vesicles as well, resulting in the secretion of ions and gliotransmitters that participate in the cell-to-cell communication. Moreover, in light of the fact that the SNARE protein syntaxin 1A and synaptotagmin I have been shown to exist in secretory granules of chromaffin cells and interact with chromogranins A and B [86] and that cellubrevin (VAMP3), synaptobrevin 2 and synaptotagmin were shown to colocalize with secretory granule markers in anterior pituitary cells [87], it is highly likely that SNARE proteins also exist in secretory granules of astrocytes.…”

Section: Discussionmentioning

confidence: 99%

Evidence for the Existence of Secretory Granule (Dense-Core Vesicle)-Based Inositol 1,4,5-Trisphosphate-Dependent Ca2+ Signaling System in Astrocytes

et al. 2010

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BackgroundThe gliotransmitters released from astrocytes are deemed to play key roles in the glial cell-neuron communication for normal function of the brain. The gliotransmitters, such as glutamate, ATP, D-serine, neuropeptide Y, are stored in vesicles of astrocytes and secreted following the inositol 1,4,5-trisphosphate (IP3)-induced intracellular Ca2+ releases. Yet studies on the identity of the IP3-dependent intracellular Ca2+ stores remain virtually unexplored.Principal FindingsWe have therefore studied the potential existence of the IP3-sensitive intracellular Ca2+ stores in the cytoplasm of astrocytes using human brain tissue samples in contrast to cultured astrocytes that had primarily been used in the past. It was thus found that secretory granule marker proteins chromogranins and secretogranin II localize in the large dense core vesicles of astrocytes, thereby confirming the large dense core vesicles as bona fide secretory granules. Moreover, consistent with the major IP3-dependent intracellular Ca2+ store role of secretory granules in secretory cells, secretory granules of astrocytes also contained all three (types 1, 2, and 3) IP3R isoforms.SignificanceGiven that the secretory granule marker proteins chromogranins and secretogranin II are high-capacity, low-affinity Ca2+ storage proteins and chromogranins interact with the IP3Rs to activate the IP3R/Ca2+ channels, i.e., increase both the mean open time and the open probability of the channels, these results imply that secretory granules of astrocytes function as the IP3-sensitive intracellular Ca2+ store.

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Section: Discussionmentioning

confidence: 99%

Evidence for the Existence of Secretory Granule (Dense-Core Vesicle)-Based Inositol 1,4,5-Trisphosphate-Dependent Ca2+ Signaling System in Astrocytes

et al. 2010

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“…It has been shown that CgA interacts with several integral membrane proteins of secretory granules, including the inositol 1,4,5-triphosphate receptor/Ca 2ϩ channels to control intracellular Ca 2ϩ release (31)(32)(33)(34)(35), or syntaxin 1A and synaptotagmin I, which par- ticipate in the fusion complex formation during exocytotic events (36). These protein-protein interactions suggest the possibility of communication between the intragranular matrix proteins and the traffic and fusion machineries.…”

Section: Discussionmentioning

confidence: 99%

Chromogranin A Promotes Peptide Hormone Sorting to Mobile Granules in Constitutively and Regulated Secreting Cells

Montero-Hadjadje

Élias

Chevalier

et al. 2009

Journal of Biological Chemistry

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Chromogranin A (CgA) has been proposed to play a major role in the formation of dense-core secretory granules (DCGs) in neuroendocrine cells. Here, we took advantage of unique features of the frog CgA (fCgA) to assess the role of this granin and its potential functional determinants in hormone sorting during DCG biogenesis. Expression of fCgA in the constitutively secreting COS-7 cells induced the formation of mobile vesicular structures, which contained cotransfected peptide hormones. The fCgA and the hormones coexpressed in the newly formed vesicles could be released in a regulated manner. The N-and C-terminal regions of fCgA, which exhibit remarkable sequence conservation with their mammalian counterparts were found to be essential for the formation of the mobile DCG-like structures in COS-7 cells. Expression of fCgA in the corticotrope AtT20 cells increased pro-opiomelanocortin levels in DCGs, whereas the expression of N-and C-terminal deletion mutants provoked retention of the hormone in the Golgi area. Furthermore, fCgA, but not its truncated forms, promoted pro-opiomelanocortin sorting to the regulated secretory pathway. These data demonstrate that CgA has the intrinsic capacity to induce the formation of mobile secretory granules and to promote the sorting and release of peptide hormones. The conserved terminal peptides are instrumental for these activities of CgA.Eukaryotic cells share the capacity to rapidly secrete proteins through the constitutive secretory pathway. The fundamental feature of neuroendocrine and endocrine cells is the occurrence of dense-core secretory granules (DCGs), 3 which are key cytoplasmic organelles responsible for secretion of hormones, neuropeptides, and neurotransmitters through the regulated secretory pathway (RSP). Storage at high concentrations of these secretory products is required for their finely tuned release in response to extracellular stimulation (1, 2). DCG biogenesis starts with the budding of immature secretory granules (ISGs) from the trans-Golgi network (TGN) through interactions between lipid rafts and protein components, in a similar manner to constitutive vesicle budding (2, 3). The ISG budding is followed by a multistep maturation process to form the mature secretory granules, including removal of the constitutive secretory proteins and lysosomal enzymes inadvertently packaged into ISGs (4).Despite increasing knowledge of the various steps of DCG formation, the nature of the sorting signals for entry of proteins into the DCGs and the molecular machinery required to generate secretory granules are not fully elucidated (5, 6). Several recent studies highlighted the role of members of the granin family, which may represent the driving force for granulogenesis in the TGN (2), although this notion has been a matter of debate (7). Granins are soluble acidic proteins widely distributed in endocrine and neuroendocrine cells, which are characterized by the ability to aggregate at acidic pH and a high Ca 2ϩ environment (8, 9). These conditions are found in the lum...

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“…Because one of the primary functions of secretory cells is to store and secrete molecules essential for cellular communication, and the trigger signal for secretion is Ca 2+ (7–9, 33), the presence of most of cellular Ca 2+ and IP 3 R/Ca 2+ channels along with the highest concentrations of chromogranins in secretory granules highlights the extraordinary efficiency of secretory cells to deal with their complex physiological needs. Moreover, secretory granules also contain Ca 2+ sensor proteins, such as synaptotagmin and syntaxin (98–100), which are known to participate in the Ca 2+ ‐initiated membrane fusion and exocytotic processes (101–103). These membrane proteins will initiate the fusion process and pave the way for secretion of intragranular contents to the extracellular space and on to the bloodstream (Fig.…”

Section: Physiological Significancementioning

confidence: 99%

Secretory granules in inositol 1,4,5‐trisphosphate‐dependent Ca²⁺signaling in the cytoplasm of neuroendocrine cells

Yoo

2009

FASEB j.

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Of all the intracellular organelles, secretory granules contain by far the highest calcium concentration; secretory granules of typical neuroendocrine chromaffin cells contain approximately 40 mM Ca(2+) and occupy approximately 20% cell volume, accounting for >60% of total cellular calcium. They also contain the majority of cellular inositol 1,4,5-trisphosphate receptors (IP(3)Rs) in addition to the presence of >2 mM of chromogranins A and B that function as high-capacity, low-affinity Ca(2+) storage proteins. Chromogranins A and B also interact with the IP(3)Rs and activate the IP(3)R/Ca(2+) channels. In experiments with both neuroendocrine PC12 and nonneuroendocrine NIH3T3 cells, in which the number of secretory granules present was changed by either suppression or induction of secretory granule formation, secretory granules were demonstrated to account for >70% of the IP(3)-induced Ca(2+) releases in the cytoplasm. Moreover, the IP(3) sensitivity of secretory granule IP(3)R/Ca(2+) channels is at least approximately 6- to 7-fold more sensitive than those of the endoplasmic reticulum, thus enabling secretory granules to release Ca(2+) ahead of the endoplasmic reticulum. Further, there is a direct correlation between the number of secretory granules and the IP(3) sensitivity of cytoplasmic IP(3)R/Ca(2+) channels and the increased ratio of IP(3)-induced cytoplasmic Ca(2+) release, highlighting the importance of secretory granules in the IP(3)-dependent Ca(2+) signaling. Given that secretory granules are present in all secretory cells, these results presage critical roles of secretory granules in the control of cytoplasmic Ca(2+) concentrations in other secretory cells.-Yoo, S. H. Secretory granules in inositol 1,4,5-trisphosphate-dependent Ca(2+) signaling in the cytoplasm of neuroendocrine cells.

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Presence of syntaxin 1A in secretory granules of chromaffin cells and interaction with chromogranins A and B

Cited by 12 publications

References 40 publications

Evidence for the Existence of Secretory Granule (Dense-Core Vesicle)-Based Inositol 1,4,5-Trisphosphate-Dependent Ca2+ Signaling System in Astrocytes

Evidence for the Existence of Secretory Granule (Dense-Core Vesicle)-Based Inositol 1,4,5-Trisphosphate-Dependent Ca2+ Signaling System in Astrocytes

Chromogranin A Promotes Peptide Hormone Sorting to Mobile Granules in Constitutively and Regulated Secreting Cells

Secretory granules in inositol 1,4,5‐trisphosphate‐dependent Ca²⁺signaling in the cytoplasm of neuroendocrine cells

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Presence of syntaxin 1A in secretory granules of chromaffin cells and interaction with chromogranins A and B

Cited by 12 publications

References 40 publications

Evidence for the Existence of Secretory Granule (Dense-Core Vesicle)-Based Inositol 1,4,5-Trisphosphate-Dependent Ca2+ Signaling System in Astrocytes

Evidence for the Existence of Secretory Granule (Dense-Core Vesicle)-Based Inositol 1,4,5-Trisphosphate-Dependent Ca2+ Signaling System in Astrocytes

Chromogranin A Promotes Peptide Hormone Sorting to Mobile Granules in Constitutively and Regulated Secreting Cells

Secretory granules in inositol 1,4,5‐trisphosphate‐dependent Ca2+signaling in the cytoplasm of neuroendocrine cells

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Secretory granules in inositol 1,4,5‐trisphosphate‐dependent Ca²⁺signaling in the cytoplasm of neuroendocrine cells