Synaptotagmin isoforms confer distinct activation kinetics and dynamics to chromaffin cell granules

Rao, Tejeshwar C.; Rodriguez, Zuleirys Santana; Bradberry, Mazdak M.; Ranski, Alexandra H.; Dahl, Peter; Schmidtke, Michael W.; Jenkins, Paul M.; Axelrod, Daniel; Chapman, Edwin R.; Giovannucci, David R.; Anantharam, Arun

doi:10.1085/jgp.201711757

Cited by 30 publications

(57 citation statements)

References 59 publications

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“…Using this approach, we demonstrate that cells without Syt-7 release cargos at significantly faster rates than WT cells expressing a full complement of synaptotagmins. Consistent with data from overexpression studies (12,13), this suggests that endogenous Syt-7 constrains rather than accelerates fusion pore expansion (11).…”

Section: Introductionsupporting

confidence: 79%

“…Certain lumenal cargo proteins, such as tissue Plasminogen Activator (tPA), exhibit intrinsically slower release or "discharge" times during exocytosis (27,28) In the case of tPA, this has been attributed to the protein's ability to stabilize the curvature of the fusion pore and thereby limit its rate of expansion (16). Here, we wanted to address whether tPA re-lease from fused vesicles may be hastened by the abrogation of Syt-7 expression -a protein which imposes its own constraints on fusion pore expansion (12,13). As before, the rate of release of tPA-pHl was measured in both WT and Syt-7 KO cells depolarized with KCl.…”

Section: Resultsmentioning

confidence: 99%

“…Cells were subsequently imaged using a Zeiss 880 confocal microscope (Zeiss, Oberkochen, Germany) with a 63x oil immersion objective in airyscan mode. Images were analyzed using Imaris Software (Bitplane, Zurich, Switzerland) using the "spot" function module for puncta detection and colocalization analysis (12). Cells were subsequently imaged using a Zeiss 880 confocal microscope (Zeiss, Oberkochen, Germany) with a 63x oil immersion objective in airyscan mode.…”

Section: R a F Tmentioning

confidence: 99%

“…Electrophysiological recordings Primary cultures of mouse chromaffin cells were maintained on glass bottom dishes and mounted onto the stage of a Nikon Eclipse TE2000, as previously described (12). A micro-manifold and polyamidecoated capillary was positioned in the field of view and bath solutions were exchanged through using a pressure-driven reservoir system.…”

Section: R a F Tmentioning

confidence: 99%

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Synaptotagmin-7 endows a population of chromaffin cell vesicles with enhanced calcium sensing and delayed content release properties

Bendahmane

Kreutzberger

Chapman-Morales

et al. 2019

Preprint

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Synaptotagmin-7 (Syt-7) is one of two major calcium sensors for exocytosis in adrenal chromaffin cells, the other being synaptotagmin-1 (Syt-1). Despite its undoubted importance, questions remain as to the functional and physiological role of Syt-7 in secretion. We examined this issue using two distinct preparations -mouse chromaffin cells lacking endogenous Syt-7 (KO cells) and a reconstituted system employing cell-derived vesicles expressing either Syt-7 or Syt-1. First, we report using immunofluorescence that Syt-7 exhibits a punctate intracellular distribution consistent with its sorting to organelles, including dense core vesicles. We also find that the likelihood of vesicle fusion in KO cells is markedly lower than in WT cells. When fusion does occur, cargoes are discharged more rapidly when only Syt-1 is available to facilitate release. A distinctive characteristic of KO cells is that secretion runs down after prolonged cholinergic stimulation. In contrast, exocytosis persists in WT cells even with extended exposure to acetylcholine, suggesting a key role for Syt-7 in sustaining the secretory response. To determine the extent to which the aforementioned results are attributable purely to Syt-7, vesicles expressing only Syt-7 or Syt-1 were triggered to fuse on planar supported bilayers bearing plasma membrane SNARE proteins. Here, as in cells, Syt-7 confers substantially greater calcium sensitivity to vesicle fusion than Syt-1 and slows the rate at which cargos are released. Overall, this study demonstrates that by virtue of its high affinity for calcium, Syt-7 plays a central role in regulating secretory output from adrenal chromaffin cells. synaptotagmin | chromaffin cell | exocytosis | granule Correspondence: arunanan@umich.edu Taken together, our data highlight clear functional distinc-Bendahmane et al. | bioRχiv | July 16, 2019 | 1-5

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Section: Introductionsupporting

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Section: R a F Tmentioning

confidence: 99%

Section: R a F Tmentioning

confidence: 99%

See 2 more Smart Citations

Synaptotagmin-7 endows a population of chromaffin cell vesicles with enhanced calcium sensing and delayed content release properties

Bendahmane

Kreutzberger

Chapman-Morales

et al. 2019

Preprint

Self Cite

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show abstract

“…For example, in response to elevated intracellular calcium (Ca 2+ ), the chromaffin cells of the adrenal medulla secrete the neurotransmitter epinephrine (also known as adrenaline) into the bloodstream, along with several other neuropeptides and neurotransmitters. In their paper published this month in JGP, explore how different synaptotagmin isoforms help regulate secretory activity by chromaffin cells (1). …”

mentioning

confidence: 99%