Article

Duncan, R.R. et al. Functional and spatial segregation of secretory vesicle pools according to vesicle age. Nature 422, 176-180

The University of Edinburgh, Edinburgh, Scotland, United Kingdom
Nature (Impact Factor: 41.46). 04/2003; 422(6928):176-80. DOI: 10.1038/nature01389
Source: PubMed

ABSTRACT

Synaptic terminals and neuroendocrine cells are packed with secretory vesicles, only a few of which are docked at the plasma membrane and readily releasable. The remainder are thought to constitute a large cytoplasmic reserve pool awaiting recruitment into the readily releasable pool (RRP) for exocytosis. How vesicles are prioritized in recruitment is still unknown: the choice could be random, or else the oldest or the newest ones might be favoured. Here we show, using a fluorescent cargo protein that changes colour with time, that vesicles in bovine adrenal chromaffin cells segregate into distinct populations, based on age. Newly assembled vesicles are immobile (morphologically docked) at the plasma membrane shortly after biogenesis, whereas older vesicles are mobile and located deeper in the cell. Different secretagogues selectively release vesicles from the RRP or, surprisingly, selectively from the deeper cytoplasmic pool. Thus, far from being equal, vesicles are segregated functionally and spatially according to age.

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    • "Prior in vitro studies detected robust release of ANF-GFP from single DCVs in chromaffin cells, undifferentiated PC12 cells, and differentiated PC12 cell growth cones and more limited ANF-GFP release from cultured hippocampal neurons (Han et al., 1999; Barg et al., 2002; Duncan et al., 2003; Ng et al., 2003; Xia et al., 2009). However, the stimuli used in these studies are not amenable to imaging transgenically expressed ANF-GFP at the native Drosophila NMJ: bath-applied K + directly evokes muscle contraction that "
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    Preview · Article · Apr 2015 · Molecular biology of the cell
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    • "Cargo sorting into LDCVs is a very complicated and highly regulated process. It has been postulated that there different LDCV populations exist, which might have different constituents (Duncan et al., 2003; Grabner et al., 2005; Watanabe et al., 1991). The segregation of CgA and SgII in different populations implicates that there exist different sorting machineries for these granins (Watanabe et al., 1991). "
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    ABSTRACT: The large dense-core vesicle (LDCV), a type of lysosome-related organelle, is involved in the secretion of hormones and neuropeptides in specialized secretory cells. The granin family is a driving force in LDCV biogenesis, but the machinery for granin sorting to this biogenesis pathway is largely unknown. The mu mutant mouse, which carries a spontaneous null mutation on the Muted gene (also known as Bloc1s5) that encodes a subunit of lysosome-related organelles complex-1 (BLOC-1), is a mouse model of Hermansky-Pudlak syndrome. We here found that LDCVs were enlarged in mu adrenal chromaffin cells. Chromogranin A (CgA) was increased in mu adrenals and muted-knockdown cells. The increased CgA in mu mice was likely due to the failure of its sorting-out, which impairs LDCV maturation and docking. In mu chromaffin cells, the size of readily releasable pool and the vesicle release frequency were reduced. Our studies suggest that the muted protein is involved in the sorting-out of CgA during the biogenesis of LDCVs.
    Full-text · Article · Feb 2015 · Journal of Cell Science
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    • "R110-labeled old insulin-HT signals showed a punctate pattern throughout the cytoplasm that largely did not overlap with new insulin-HT TMR signals (Fig. 3A). This result is consistent with previous observations using atrial natriuretic factor-tagged fluorescent timer protein, in which secretory vesicles segregated into distinct populations according to age in bovine adrenal chromaffin cells [17]. In contrast to chromaffin cells, in which young rather than older secretory vesicles preferentially docked to the plasma membrane, newly synthesized insulin-HT TMR signals were rarely observed in sections either from the top and bottom z-axis stages in MIN6 cells, whereas R110 signals from older insulin were present throughout the stages (Figs. "
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