Light and Electron Microscopic Study of Changes in the Organization of the Cortical Actin Cytoskeleton During Chromaffin Cell Secretion

Tchakarov, L.; Zhang, Li; Rosé, Sergio D.; Tang, Ruihua; Trifaró, J. M.

doi:10.1177/002215549804600208

Cited by 26 publications

(18 citation statements)

References 30 publications

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“…We do not know the functional relevance of this process as vesicles do not seem to access the interior of these zones as they only move only along the F-actin walls. The formation of these polygons during secretion is supported by electron microscopy studies in fixed chromaffin cells (Tchakarov et al, 1998).…”

Section: Discussionmentioning

confidence: 75%

Real-time dynamics of the F-actin cytoskeleton during secretion from chromaffin cells

Giner¹,

Ñeco²,

Francés³

et al. 2005

Journal of Cell Science

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Transmitted light images showed an intricate and dynamic cytoplasmic structural network in cultured bovine chromaffin cells observed under high magnification. These structures were sensitive to chemicals altering F-actin-myosin and colocalised with peripheral F-actin, β-actin and myosin II. Interestingly, secretagogues induced a Ca2+-dependent, rapid (>10 second) and transitory (60-second cycle) disassembling of these cortical structures. The simultaneous formation of channel-like structures perpendicular to the plasmalemma conducting vesicles to the cell limits and open spaces devoid of F-actin in the cytoplasm were also observed. Vesicles moved using F-actin pathways and avoided diffusion in open, empty zones. These reorganisations representing F-actin transfer from the cortical barrier to the adjacent cytoplasmic area have been also confirmed by studying fluorescence changes in cells expressing GFP-β-actin. Thus, these data support the function of F-actin-myosin II network acting simultaneously as a barrier and carrier system during secretion, and that transmitted light images could be used as an alternative to fluorescence in the study of cytoskeleton dynamics in neuroendocrine cells.

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Section: Discussionmentioning

confidence: 75%

Real-time dynamics of the F-actin cytoskeleton during secretion from chromaffin cells

Giner¹,

Ñeco²,

Francés³

et al. 2005

Journal of Cell Science

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“…6). Previous studies report nicotine-mediated suppression of F-actin levels in chromaffin cells (32). Likewise, acetylcholine, the predominant neurotransmitter released by VNS, blocked the translocation of F-actin which is necessary for leukocyte-endothelial cell adhesion (33).…”

Section: Discussionmentioning

confidence: 90%

Cholinergic Neural Signals to the Spleen Down-Regulate Leukocyte Trafficking via CD11b

Huston

Rosas-Ballina

Xue

et al. 2009

The Journal of Immunology

112

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The cholinergic anti-inflammatory pathway is a physiological mechanism that inhibits cytokine production and diminishes tissue injury during inflammation. Recent studies demonstrate that cholinergic signaling reduces adhesion molecule expression and chemokine production by endothelial cells and suppresses leukocyte migration during inflammation. It is unclear how vagus nerve stimulation regulates leukocyte trafficking because the vagus nerve does not innervate endothelial cells. Using mouse models of leukocyte trafficking, we show that the spleen, which is a major point of control for cholinergic modulation of cytokine production, is essential for vagus nerve-mediated regulation of neutrophil activation and migration. Administration of nicotine, a pharmacologic agonist of the cholinergic anti-inflammatory pathway, significantly reduces levels of CD11b, a β2-integrin involved in cell adhesion and leukocyte chemotaxis, on the surface of neutrophils in a dose-dependent manner and this function requires the spleen. Similarly, vagus nerve stimulation significantly attenuates neutrophil surface CD11b levels only in the presence of an intact and innervated spleen. Further mechanistic studies reveal that nicotine suppresses F-actin polymerization, the rate-limiting step for CD11b surface expression. These studies demonstrate that modulation of leukocyte trafficking via cholinergic signaling to the spleen is a specific, centralized neural pathway positioned to suppress the excessive accumulation of neutrophils at inflammatory sites. Activating this mechanism may have important therapeutic potential for preventing tissue injury during inflammation.

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“…Activation of PKC by TPA or by diacylglycerol (DAG) caused polymerization of actin, while PKC antagonist inhibited the formation of actin storage (Takashi 1997). However, in other studies, stimulation of PKC by phorbol esters was accompanied by a focal and transient disruption of the cortical F-actin network (Vitale et al 1991, Tchakarov et al 1998, Trifaro et al 2002. These contradictory results reflect the lack of clarity regarding the role of PKC, actin and actin-associated proteins in the regulation of secretory events (Muallem et al 1995).…”

Section: Introductionmentioning

confidence: 95%

The involvement of protein kinase C and actin filaments in cortical granule exocytosis in the rat

Eliyahu¹,

Tsaadon²,

Shtraizent³

et al. 2005

Reproduction

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Mammalian sperm -egg fusion results in cortical granule exocytosis (CGE) and resumption of meiosis. Studies of various exocytotic cells suggest that filamentous actin (F-actin) blocks exocytosis by excluding secretory vesicles from the plasma membrane. However, the exact function of these microfilaments, in mammalian egg CGE, is still elusive. In the present study we investigated the role of actin in the process of CGE, and the possible interaction between actin and protein kinase C (PKC), by using coimmunoprecipitation, immunohistochemistry and confocal microscopy. We identified an interaction between actin and the PKC alpha isoenzyme in non-activated metaphase II (MII) eggs and in eggs activated by phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA). F-actin was evenly distributed throughout the egg's cytosol with a marked concentration at the cortex and at the plasma membrane. A decrease in the fluorescence signal of F-actin, which represents its depolymerization/ reorganization, was detected upon fertilization and upon parthenogenetic activation. Exposing the eggs to drugs that cause either polymerization or depolymerization of actin (jasplakinolide (JAS) and cytochalasin D (CD) respectively) did not induce or prevent CGE. However, CD, but not JAS, followed by a low dose of TPA doubled the percentage of eggs undergoing complete CGE, as compared with TPA alone. We further demonstrated that myristoylated alanin-rich C kinase substrate (MARCKS), a protein known to cross-link F-actin in other cell types, is expressed in rat eggs and is colocalized with actin. In view of our results, we suggest that the cytoskeletal cortex is not a mere physical barrier that blocks CGE, but rather a dynamic network that can be maneuvered towards allowing CGE by activated actin-associated proteins and/or by activated PKC.

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Light and Electron Microscopic Study of Changes in the Organization of the Cortical Actin Cytoskeleton During Chromaffin Cell Secretion

Cited by 26 publications

References 30 publications

Real-time dynamics of the F-actin cytoskeleton during secretion from chromaffin cells

Real-time dynamics of the F-actin cytoskeleton during secretion from chromaffin cells

Cholinergic Neural Signals to the Spleen Down-Regulate Leukocyte Trafficking via CD11b

The involvement of protein kinase C and actin filaments in cortical granule exocytosis in the rat

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