Rapid ATP‐Dependent Priming of Secretory Granules Precedes Ca<sup>2+</sup> ‐Induced Exocytosis in Mouse Pancreatic B‐Cells

Eliasson, Lena; Renström, Erik; Ding, Wei‐Guang; Proks, Peter; Rorsman, Patrik

doi:10.1111/j.1469-7793.1997.399bh.x

Cited by 204 publications

(208 citation statements)

References 38 publications

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“…3). This is unexpected, given the established role of NSF in the sustained component of secretion in neuroendocrine cells (Eliasson et al, 1997;Xu et al, 1999); however, the roles of NSF in synapses are controversial. For example, Schweizer et al (1998) showed that NSF is involved in supporting rapid kinetics of transmitter release in squid giant synapses.…”

Section: Roles Of Nsf and Protein Kinases In Vesicle Recruitmentmentioning

confidence: 75%

“…We thus made an effort to find factors that are related to ATP hydrolysis and specifically involved in the recovery of the second component. One candidate is NSF, because NEM has been shown to block recruitment of vesicles in endocrine cells (Eliasson et al, 1997;Xu et al, 1999). To test the possible involvement of NSF, we introduced NEM (1 mM) via the patch pipette and applied the same protocol as has been used in the experiments described above.…”

Section: Atp-␥s Slows Down Recruitment Of the Slowly Releasing As Welmentioning

confidence: 99%

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Involvement of Actin Polymerization in Vesicle Recruitment at the Calyx of Held Synapse

2003

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Depletion and replenishment of pools of synaptic vesicles are important determinants of short-term synaptic plasticity, but the underlying molecular mechanisms are not yet clear. As a first step toward understanding the process of vesicle recruitment, we have applied various specific agents directly to the presynaptic terminal of the calyx of Held synapse. Here we show that the nonhydrolyzable ATP analog ATP-␥S retards the recovery from vesicle pool depletion, as does latrunculin A. Phalloidin has no effects on recovery, suggesting that dynamic actin reorganization is not necessary. Unexpectedly, neither N-ethylmaleimide nor staurosporine affected the recovery, calling into question the role of N-ethylmaleimide-sensitive factor and protein kinases. The results suggest that intact actin polymerization is involved in vesicle recruitment.

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Section: Roles Of Nsf and Protein Kinases In Vesicle Recruitmentmentioning

confidence: 75%

Section: Atp-␥s Slows Down Recruitment Of the Slowly Releasing As Welmentioning

confidence: 99%

Involvement of Actin Polymerization in Vesicle Recruitment at the Calyx of Held Synapse

2003

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“…In agreement with results described in ref. 35, glucose stimulation strongly enhanced the capacitance increase in response to the train of depolarizations (Fig. 2B).…”

Section: Resultsmentioning

confidence: 99%

Neuronal calcium sensor-1 potentiates glucose-dependent exocytosis in pancreatic β cells through activation of phosphatidylinositol 4-kinase β

Gromada

Bark

Smidt

et al. 2005

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

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Cytosolic free Ca 2؉ plays an important role in the molecular mechanisms leading to regulated insulin secretion by the pancreatic ␤ cell. A number of Ca 2؉ -binding proteins have been implicated in this process. Here, we define the role of the Ca 2؉ -binding protein neuronal Ca 2؉ sensor-1 (NCS-1) in insulin secretion. In pancreatic ␤ cells, NCS-1 increases exocytosis by promoting the priming of secretory granules for release and increasing the number of granules residing in the readily releasable pool. The effect of NCS-1 on exocytosis is mediated through an increase in phosphatidylinositol (PI) 4-kinase ␤ activity and the generation of phosphoinositides, specifically PI 4-phosphate and PI 4,5-bisphosphate. In turn, PI 4,5-bisphosphate controls exocytosis through the Ca 2؉ -dependent activator protein for secretion present in ␤ cells. Our results provide evidence for an essential role of phosphoinositide synthesis in the regulation of glucose-induced insulin secretion by the pancreatic ␤ cell. We also demonstrate that NCS-1 and its downstream target, PI 4-kinase ␤, are critical players in this process by virtue of their capacity to regulate the release competence of the secretory granules.insulin ͉ phosphoinositides ͉ islet ͉ secretion ͉ Ca 2ϩ -dependent activator protein for secretion N euronal Ca 2ϩ sensor-1 (NCS-1) belongs to the family of EF-hand Ca 2ϩ -binding proteins and is mainly expressed in neuronal and neuroendocrine cells, where it enhances neurotransmission and Ca 2ϩ -dependent exocytosis (1-5). NCS-1 interacts with and regulates the activity of phosphatidylinositol 4-kinase ␤ (PI4K␤) (6-9). The members of the PI4K family catalyze the first step in the synthesis of PI 4,5-bisphosphate [PI(4,5)P 2 ], which has recently emerged as an important regulator of Ca 2ϩ -dependent secretion (10-12). Both a PI transfer protein (13) and a PI4P 5-kinase (14) are required for regulated exocytosis of dense core granules. In addition, the presence of synaptic vesicle and dense core granule-associated PI4K activity is essential for exocytosis (15,16). These data imply that generation of PI(4,5)P 2 is an important step in the event of secretion.In pancreatic ␤ cells, glucose dose-dependently increases ATP levels and decreases ADP levels (16). The resulting rise in the ATP at the expense of ADP is an important regulator of the two major signaling pathways involved in glucose-induced insulin secretion. The first of these pathways uses ATP-sensitive K ϩ channels to couple glucose metabolism with electrical activity, Ca 2ϩ influx, and initiation of insulin secretion. The second pathway is exerted at the level of granule priming and regulates the ␤ cell secretory capacity by modulation of the granules' release competence (17). The ␤ cell contains Ϸ10,000 insulincontaining secretory granules (18). Interestingly, as many as Ϸ5% of the granules are docked below the membrane. The readily releasable pool (RRP), defined by functional measurements, represents a subset (50-100 granules) of the docked pool (19). Granules belongin...

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“…The mice were sacrificed by cervical dislocation, and pancreatic islets were isolated by collagenase P digestion (Roche) (Olofsson et al 2002). Single islet cells were then prepared by gently shaking the collected islets at low extracellular [Ca 2+ ] as described (Eliasson et al 1997). Dispersed cells were plated on plastic Petri dishes (Nunc) in RPMI 1640 (SVA) supplemented with 10% fetal calf serum, 100 U/mL penicillin, and 10 µg/mL streptomycin (all from Invitrogen) in the presence of either 5 or 20 mM glucose (SigmaAldrich).…”

Section: Methods Preparation and Culture Of Cellsmentioning

confidence: 99%

Gene expression profiling in single cells from the pancreatic islets of Langerhans reveals lognormal distribution of mRNA levels

Bengtsson¹,

Ståhlberg²,

Rorsman³

et al. 2005

Genome Res.

Self Cite

359

282

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The transcriptional machinery in individual cells is controlled by a relatively small number of molecules, which may result in stochastic behavior in gene activity. Because of technical limitations in current collection and recording methods, most gene expression measurements are carried out on populations of cells and therefore reflect average mRNA levels. The variability of the transcript levels between different cells remains undefined, although it may have profound effects on cellular activities. Here we have measured gene expression levels of the five genes ActB, Ins1, Ins2, Abcc8, and Kcnj11 in individual cells from mouse pancreatic islets. Whereas Ins1 and Ins2 expression show a strong cell–cell correlation, this is not the case for the other genes. We further found that the transcript levels of the different genes are lognormally distributed. Hence, the geometric mean of expression levels provides a better estimate of gene activity of the typical cell than does the arithmetic mean measured on a cell population.

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Rapid ATP‐Dependent Priming of Secretory Granules Precedes Ca²⁺ ‐Induced Exocytosis in Mouse Pancreatic B‐Cells

Cited by 204 publications

References 38 publications

Involvement of Actin Polymerization in Vesicle Recruitment at the Calyx of Held Synapse

Involvement of Actin Polymerization in Vesicle Recruitment at the Calyx of Held Synapse

Neuronal calcium sensor-1 potentiates glucose-dependent exocytosis in pancreatic β cells through activation of phosphatidylinositol 4-kinase β

Gene expression profiling in single cells from the pancreatic islets of Langerhans reveals lognormal distribution of mRNA levels

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Rapid ATP‐Dependent Priming of Secretory Granules Precedes Ca2+ ‐Induced Exocytosis in Mouse Pancreatic B‐Cells

Cited by 204 publications

References 38 publications

Involvement of Actin Polymerization in Vesicle Recruitment at the Calyx of Held Synapse

Involvement of Actin Polymerization in Vesicle Recruitment at the Calyx of Held Synapse

Neuronal calcium sensor-1 potentiates glucose-dependent exocytosis in pancreatic β cells through activation of phosphatidylinositol 4-kinase β

Gene expression profiling in single cells from the pancreatic islets of Langerhans reveals lognormal distribution of mRNA levels

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Rapid ATP‐Dependent Priming of Secretory Granules Precedes Ca²⁺ ‐Induced Exocytosis in Mouse Pancreatic B‐Cells