Exocytosis is impaired in mucopolysaccharidosis IIIA mouse chromaffin cells

Keating, Damien J.; Winter, Marnie; Hemsley, Kim M.; Mackenzie, Kimberly D.; Teo, Ee Hiok; Hopwood, John J.; Brooks, Doug A.; Parkinson-Lawrence, Emma J.

doi:10.1016/j.neuroscience.2012.09.034

Cited by 15 publications

(9 citation statements)

References 35 publications

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“…Amperometry files were converted to Axon Binary Files (ABF Utility, version 6.0.1, Synaptosoft, USA) and secretory spikes were analysed (Mini Analysis, version 6.0.1, Synaptosoft, USA) from before and during stimulation [ 26 , 27 ]. Amperometric spikes were selected for analysis of event frequency if spike amplitude exceeded 10 times root-mean-squared noise of the baseline.…”

Section: Methodsmentioning

confidence: 99%

Serotonin-secreting enteroendocrine cells respond via diverse mechanisms to acute and chronic changes in glucose availability

et al. 2015

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BackgroundEnteroendocrine cells collectively constitute our largest endocrine tissue, with serotonin (5-HT) secreting enterochromaffin (EC) cells being the largest component (~50 %). This gut-derived 5-HT has multiple paracrine and endocrine roles. EC cells are thought to act as nutrient sensors and luminal glucose is the major absorbed form of carbohydrate in the gut and activates secretion in an array of cell types. It is unknown whether EC cells release 5-HT in response to glucose in primary EC cells. Furthermore, fasting augments 5-HT synthesis and release into the circulation. However, which nutrients cause fasting-induced synthesis of EC cell 5-HT is unknown. Here we examine the effects of acute and chronic changes in glucose availability on 5-HT release from intact tissue and single EC cells.MethodsWe utilised established approaches in our laboratories measuring 5-HT release in intact mouse colon with amperometry. We then examined single EC cells function using our published protocol in guinea-pig colon. Single cell Ca2+ imaging and amperometry were used with these cells. Real-time PCR was used along with amperometry, on primary EC cells cultured for 24 h in 5 or 25 mM glucose.ResultsWe demonstrate that acute increases in glucose, at levels found in the gut lumen rather than in plasma, trigger 5-HT release from intact colon, and cause Ca2+ entry and 5-HT release in primary EC cells. Single cell amperometry demonstrates that high glucose increases the amount of 5-HT released from individual vesicles as they undergo exocytosis. Finally, 24 h incubation of EC cells in low glucose causes an increase in the transcription of the 5-HT synthesising enzyme Tph1 as well as increasing in 5-HT secretion in EC cells.ConclusionsWe demonstrate that primary EC cells respond to acute changes in glucose availability through increases in intracellular Ca2+ the activation of 5-HT secretion, but respond to chronic changes in glucose levels through the transcriptional regulation of Tph1 to alter 5-HT synthesis.

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Section: Methodsmentioning

confidence: 99%

Serotonin-secreting enteroendocrine cells respond via diverse mechanisms to acute and chronic changes in glucose availability

et al. 2015

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“…Adult B6/CBA mice were killed humanely using isoflurane as approved by the Flinders University Animal Welfare Committee and as previously described (Keating et al, ; Mackenzie et al, ). Adrenal glands were extracted and the cortex and capsule dissected away.…”

Section: Methodsmentioning

confidence: 99%

Fusion Pore Size Limits 5-HT Release From Single Enterochromaffin Cell Vesicles

et al. 2015

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Enterochromaffin cells are the major site of serotonin (5-HT) synthesis and secretion providing ∼95% of the body's total 5-HT. 5-HT can act as a neurotransmitter or hormone and has several important endocrine and paracrine roles. We have previously demonstrated that EC cells release small amounts of 5-HT per exocytosis event compared to other endocrine cells. We utilized a recently developed method to purify EC cells to demonstrate the mechanisms underlying 5-HT packaging and release. Using the fluorescent probe FFN511, we demonstrate that EC cells express VMAT and that VMAT plays a functional role in 5-HT loading into vesicles. Carbon fiber amperometry studies illustrate that the amount of 5-HT released per exocytosis event from EC cells is dependent on both VMAT and the H(+)-ATPase pump, as demonstrated with reserpine or bafilomycin, respectively. We also demonstrate that increasing the amount of 5-HT loaded into EC cell vesicles does not result in an increase in quantal release. As this indicates that fusion pore size may be a limiting factor involved, we compared pore diameter in EC and chromaffin cells by assessing the vesicle capture of different-sized fluorescent probes to measure the extent of fusion pore dilation. This identified that EC cells have a reduced fusion pore expansion that does not exceed 9 nm in diameter. These results demonstrate that the small amounts of 5-HT released per fusion event in EC cells can be explained by a smaller fusion pore that limits 5-HT release capacity from individual vesicles.

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“…During defi ciency of neuraminidase I there is increased exocytosis [51,52]. In contrast, impaired exocytosis and decreased release of catecholamines were reported in chromaffin cells [53].…”

Section: Lysosomal Storage Versus Cell Functionmentioning

confidence: 98%

Secondary biochemical and morphological consequences in lysosomal storage diseases

Alroy

Garganta

Wiederschain

2014

Biochemistry Moscow

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More than 50 hereditary lysosomal storage disorders (LSDs) are currently described. Most of these disorders are due to a deficiency of certain hydrolases/glycosidases and subsequent accumulation of nonhydrolyzable carbohydrate-containing compounds in lysosomes. Such accumulation causing hypertrophy of the lysosomal compartment is a characteristic feature of affected cells in LSDs. The investigation of biochemical and cellular parameters is of particular interest for understanding "life" of lysosomes in the normal state and in LSDs. This review highlights the wide spectrum of biochemical and morphological changes during developing LSDs that are extremely critical for many metabolic processes inside the various cells and tissues of affected persons. The data presented will help establish new complex strategies for metabolic correction of LSDs.

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Exocytosis is impaired in mucopolysaccharidosis IIIA mouse chromaffin cells

Cited by 15 publications

References 35 publications

Serotonin-secreting enteroendocrine cells respond via diverse mechanisms to acute and chronic changes in glucose availability

Serotonin-secreting enteroendocrine cells respond via diverse mechanisms to acute and chronic changes in glucose availability

Fusion Pore Size Limits 5-HT Release From Single Enterochromaffin Cell Vesicles

Secondary biochemical and morphological consequences in lysosomal storage diseases

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