Microinjection of Ca++-calmodulin causes a localized depolymerization of microtubules.

Keith, Charles H.; DiPaola, Mario; Maxfield, Frederick R.; Shelanski, Michael L.

doi:10.1083/jcb.97.6.1918

Cited by 178 publications

(83 citation statements)

References 16 publications

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“…6B,C). It has been previously described that local Ca 2+ increments can depolymerize microtubules (Keith et al, 1983). Thus, a lower concentration of Ca 2+ at axon terminals due to P2X7 inhibition can induce a higher rate of microtubule polymerization, which invades the actin domain of the growth cone.…”

Section: P2x7 Antagonists Modify Growth-cone Morphology and Activate Fakmentioning

confidence: 98%

Inhibition of the ATP-gated P2X7 receptor promotes axonal growth and branching in cultured hippocampal neurons

Dı́az-Hernández

Puerto

Díaz‐Hernandéz

et al. 2008

Journal of Cell Science

118

103

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During the establishment of neural circuits, the axons of neurons grow towards their target regions in response to both positive and negative stimuli. Because recent reports show that Ca2+ transients in growth cones negatively regulate axonal growth, we studied how ionotropic ATP receptors (P2X) might participate in this process. Our results show that exposing cultured hippocampal neurons to ATP induces Ca2+ transients in the distal domain of the axon and the concomitant inhibition of axonal growth. This effect is mediated by the P2X7 receptor, which is present in the growth cone of the axon. Pharmacological inhibition of P2X7 or its silencing by shRNA interference induces longer and more-branched axons, coupled with morphological changes to the growth cone. Our data suggest that these morphological changes are induced by a signalling cascade in which CaMKII and FAK activity activates PI3-kinase and modifies the activity of its downstream targets. Thus, in the absence or inactivation of P2X7 receptor, axons grow more rapidly and form more branches in cultured hippocampal neurons, indicative that ATP exerts a negative influence on axonal growth. These data suggest that P2X7 antagonists have therapeutic potential to promote axonal regeneration.

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Section: P2x7 Antagonists Modify Growth-cone Morphology and Activate Fakmentioning

confidence: 98%

Inhibition of the ATP-gated P2X7 receptor promotes axonal growth and branching in cultured hippocampal neurons

Dı́az-Hernández

Puerto

Díaz‐Hernandéz

et al. 2008

Journal of Cell Science

118

103

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“…In vivo, microtubules are sensitive to intracellular calcium concentrations, an effect mediated by calmodulin. For example, microinjection of fibroblasts with calcium-saturated calmodulin induces a rapid disruption of microtubules at the injection site (55,56). Furthermore, microinjection of calcium chelators inhibits mitosis (57-59), again implicating calcium in this process.…”

Section: Fig 7 Western Blot Analysis Of P62 Phosphorylated In Vivomentioning

confidence: 99%

Molecular Characterization of p62, a Mitotic Apparatus Protein Required for Mitotic Progression

Ye¹,

Sloboda

1997

Journal of Biological Chemistry

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Controlled microtubule disassembly occurs during anaphase A, the stage of mitosis characterized by the movement of the chromosomes toward the poles, an event thought to be powered by molecular motors that reside at the kinetochores. The kinetochore microtubules selectively disassemble during anaphase A, and if the microtubules are prevented from disassembling, e.g. by treatment with the microtubule stabilizing, anti-tumor drug Taxol, then mitosis ceases. Microtubule depolymerization can be induced by calcium, and calcium has been shown to result in the shortening of the distance separating the poles and movement of the chromosomes toward the poles (1). Furthermore, microtubule disassembly is necessary for the reactivation of chromosome movement in lysed cells (2), and isolated mitotic chromosomes can be translocated in association with a single microtubule in vitro as the result of microtubule depolymerization (3, 4). Thus, a critical step in anaphase is the controlled disassembly of the kinetochore microtubules.We have previously demonstrated that a protein of 62 kDa (p62), a substrate of a calcium/calmodulin-dependent protein kinase, is associated with the mitotic apparatus (5, 6). Both p62 and the kinase responsible for its phosphorylation copurify with mitotic apparatuses isolated from first cell cycle sea urchin embryos (5, 7). Importantly, the phosphorylation of p62 has been shown to correlate directly with the disassembly of microtubules in isolated mitotic apparatuses (5). Furthermore, microinjection of sea urchin embryos with affinity-purified antibodies to p62 inhibits progression through the cell cycle, specifically at the metaphase to anaphase transition (6). Because p62 is present at constant levels through at least two cell cycles (8), p62 dephosphorylation must be due to the action of a specific phosphatase and not to the degradation of the protein, as occurs, for example, with the cyclins. In fact, the existence of protein phosphatase 1 in the mitotic apparatus isolated from sea urchin embryos that dephosphorylates p62 has been demonstrated by pharmacological studies with phosphatase inhibitors (9). Finally, the subcellular localization of p62 varies with the cell cycle. During mitosis, p62 is associated with the mitotic apparatus, particularly with the microtubules (6,8,10), while during interphase, p62 resides in the nucleus (8, 10).Based on this background, our working hypothesis is that phosphorylation and dephosphorylation of p62 play key roles in controlling cell division, particularly during anaphase A, by permitting kinetochore microtubule disassembly at the appropriate time during mitosis. As the logical next step in elucidating the mode of action of p62 in mitosis, we present here a characterization of the polypeptide based on its deduced amino acid sequence obtained from cloned cDNA. The p62 polypeptide is highly acidic, yet contains distinct subdomains of alternating clusters of basic and acidic residues. Furthermore, confocal microscopy reveals that during interphase the protein bind...

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“…In addition, second messenger signals may regulate the cytoskeleton. For example, Ca 2ϩ (50) or Ca 2ϩ -calmodulin can lead to microtubule disassembly (51), an effect that may be modulated by specific microtubule-associated proteins (52). This potential feedback process of Ca 2ϩ on the cytoskeleton might be important for microtubule localization in the secretory pole region.…”

Section: Microtubules Regulate Ca 2ϩ Spiking In Acinar Cellsmentioning

confidence: 99%

Microtubules Regulate Local Ca2+ Spiking in Secretory Epithelial Cells

Fogarty¹,

Kidd²,

Turner³

et al. 2000

Journal of Biological Chemistry

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The role of the cytoskeleton in regulating Ca 2؉ release has been explored in epithelial cells. Trains of local Ca 2؉ spikes were elicited in pancreatic acinar cells by infusion of inositol trisphosphate through a whole cell patch pipette, and the Ca 2؉ -dependent Cl ؊ current spikes were recorded. The spikes were only transiently inhibited by cytochalasin B, an agent that acts on microfilaments. In contrast, nocodazole (5-100 M), an agent that disrupts the microtubular network, dose-dependently reduced spike frequency and decreased spike amplitude leading to total blockade of the response. Consistent with an effect of microtubular disruption, colchicine also inhibited spiking but neither Me 2 SO nor ␤-lumicolchicine, an inactive analogue of colchicine, had any effect. The microtubule-stabilizing agent, taxol, also inhibited spiking. The nocodazole effects were not due to complete loss of function of the Ca 2؉ signaling apparatus, because supramaximal carbachol concentrations were still able to mobilize a Ca 2؉ response. Finally, as visualized by 2-photon excitation microscopy of ERTracker, nocodazole promoted a loss of the endoplasmic reticulum in the secretory pole region. We conclude that microtubules specifically maintain localized Ca 2؉ spikes at least in part because of the local positioning of the endoplasmic reticulum.

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Microinjection of Ca++-calmodulin causes a localized depolymerization of microtubules.

Cited by 178 publications

References 16 publications

Inhibition of the ATP-gated P2X7 receptor promotes axonal growth and branching in cultured hippocampal neurons

Inhibition of the ATP-gated P2X7 receptor promotes axonal growth and branching in cultured hippocampal neurons

Molecular Characterization of p62, a Mitotic Apparatus Protein Required for Mitotic Progression

Microtubules Regulate Local Ca2+ Spiking in Secretory Epithelial Cells

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