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Annexin A2-dependent actin bundling promotes secretory granule docking to the plasma membrane and exocytosis.

Gabel M, Delavoie F, Demais V, Royer C, Bailly Y, Vitale N, Bader MF, Chasserot-Golaz S - J. Cell Biol. (2015)

Bottom Line: Annexin A2, a calcium-, actin-, and lipid-binding protein involved in exocytosis, mediates the formation of lipid microdomains required for the structural and spatial organization of fusion sites at the plasma membrane.When an annexin A2 mutant with impaired actin filament-bundling activity was expressed, the formation of plasma membrane lipid microdomains and the number of exocytotic events were decreased and the fusion kinetics were slower, whereas the pharmacological activation of the intrinsic actin-bundling activity of endogenous annexin A2 had the opposite effects.Thus, annexin A2-induced actin bundling is apparently essential for generating active exocytotic sites.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France.

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The actin-bundling activity of AnxA2 modulates the formation of the initial fusion pore. (A) Schema showing the parameters of the PSF signal measured in B, C, and D panels. NT, nontransfected cells; A2-WT, cells transfected with AnxA2-GFP WT; A2-K286A, cells transfected with AnxA2-K286A-GFP; NT + WA, cells treated for 1 h with 5 µM WA. Data are expressed as mean ± SEM (error bars). *, P < 0.05; **, P < 0.01.
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fig8: The actin-bundling activity of AnxA2 modulates the formation of the initial fusion pore. (A) Schema showing the parameters of the PSF signal measured in B, C, and D panels. NT, nontransfected cells; A2-WT, cells transfected with AnxA2-GFP WT; A2-K286A, cells transfected with AnxA2-K286A-GFP; NT + WA, cells treated for 1 h with 5 µM WA. Data are expressed as mean ± SEM (error bars). *, P < 0.05; **, P < 0.01.

Mentions: Amperometric spikes are often preceded by the so-called prespike foot (PSF) currents, believed to reflect the slow release of catecholamines through an initial narrow fusion pore, before its subsequent rapid expansion that gives rise to the spike. Significant changes in PSF parameters were also observed (Fig. 8 and Table 1). Chromaffin cells expressing AnxA2-K286A exhibited significantly longer PSF (24.3 ± 2.1 ms versus 15.7 ± 2.1 ms in nontransfected cells) and an increase in foot charge (+30%), whereas WA-treated cells showed shorter and smaller PSF. Thus, these amperometric data are consistent with a role for AnxA2-dependent actin filament-bundling activity in the recruitment of secretory granules (number of exocytotic events), and possibly in the stabilization of the nascent fusion pore and its enlargement, thereby allowing full fusion in the late stage of exocytosis.


Annexin A2-dependent actin bundling promotes secretory granule docking to the plasma membrane and exocytosis.

Gabel M, Delavoie F, Demais V, Royer C, Bailly Y, Vitale N, Bader MF, Chasserot-Golaz S - J. Cell Biol. (2015)

The actin-bundling activity of AnxA2 modulates the formation of the initial fusion pore. (A) Schema showing the parameters of the PSF signal measured in B, C, and D panels. NT, nontransfected cells; A2-WT, cells transfected with AnxA2-GFP WT; A2-K286A, cells transfected with AnxA2-K286A-GFP; NT + WA, cells treated for 1 h with 5 µM WA. Data are expressed as mean ± SEM (error bars). *, P < 0.05; **, P < 0.01.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4555831&req=5

fig8: The actin-bundling activity of AnxA2 modulates the formation of the initial fusion pore. (A) Schema showing the parameters of the PSF signal measured in B, C, and D panels. NT, nontransfected cells; A2-WT, cells transfected with AnxA2-GFP WT; A2-K286A, cells transfected with AnxA2-K286A-GFP; NT + WA, cells treated for 1 h with 5 µM WA. Data are expressed as mean ± SEM (error bars). *, P < 0.05; **, P < 0.01.
Mentions: Amperometric spikes are often preceded by the so-called prespike foot (PSF) currents, believed to reflect the slow release of catecholamines through an initial narrow fusion pore, before its subsequent rapid expansion that gives rise to the spike. Significant changes in PSF parameters were also observed (Fig. 8 and Table 1). Chromaffin cells expressing AnxA2-K286A exhibited significantly longer PSF (24.3 ± 2.1 ms versus 15.7 ± 2.1 ms in nontransfected cells) and an increase in foot charge (+30%), whereas WA-treated cells showed shorter and smaller PSF. Thus, these amperometric data are consistent with a role for AnxA2-dependent actin filament-bundling activity in the recruitment of secretory granules (number of exocytotic events), and possibly in the stabilization of the nascent fusion pore and its enlargement, thereby allowing full fusion in the late stage of exocytosis.

Bottom Line: Annexin A2, a calcium-, actin-, and lipid-binding protein involved in exocytosis, mediates the formation of lipid microdomains required for the structural and spatial organization of fusion sites at the plasma membrane.When an annexin A2 mutant with impaired actin filament-bundling activity was expressed, the formation of plasma membrane lipid microdomains and the number of exocytotic events were decreased and the fusion kinetics were slower, whereas the pharmacological activation of the intrinsic actin-bundling activity of endogenous annexin A2 had the opposite effects.Thus, annexin A2-induced actin bundling is apparently essential for generating active exocytotic sites.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut des Neurosciences Cellulaires et Intégratives, UPR3212 Centre National de la Recherche Scientifique, Université de Strasbourg, F-67084 Strasbourg, France.

Show MeSH
Related in: MedlinePlus