Calcium hotspots caused by L-channel clustering promote morphological changes in neuronal growth cones

Silver, R. Angus; Lamb, Angela G.; Bolsover, Stephen R.

doi:10.1038/343751a0

Cited by 167 publications

(89 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ca2+ and whole-cell patch-clamped for [Ca2+]i measurement as described before (Silver et al 1990 Taken together with similar findings in mouse neuroblastoma cells (Silver et al 1989) The inactivation rate of many K+ and Na' currents increases with membrane depolarization. This, coupled with the greater net quantal charge required to gate inactivation as opposed to activation (McCormack et al 1991), suggests that these two processes are structurally different.…”

Section: Referencessupporting

confidence: 69%

“…The results are not consistent with pressure primarily affecting the agonist-receptor interaction or mimicking the effect of cooling, and they are unlike the effects of hydrostatic pressure on the Ach-R channel (Heinemann et al 1987). (Silver et al 1990). We have tested whether similar channel clustering is found on growth cones of primary neurones.…”

Section: Referencesmentioning

confidence: 99%

See 1 more Smart Citation

Proceedings of the Physiological Society, 14‐15 February 1992, Bristol Meeting: Communications

1992

The Journal of Physiology

View full text Add to dashboard Cite

Brown adipose tissue (BAT) possesses atypical f3-adrenoceptors (fi3) which stimulate energy expenditure by increasing lipogenesis and thermogenesis. Holloway et al. (1991) reported that ICI D7114 selectively stimulates these atypical k3-receptors, increasing BAT oxygen consumption and thermogenesis.We have previously reported that CBA/Ca obese diabetic mice exhibit reduced lipogenesis compared to normal littermates (Al-Qatari et al. 1991) .In vivo lipogenesis rates were estimated by measuring the incorporation of 3H into fatty acids extracted from adipose tissue following I.P. injection of 3H20 (Mercer & Trayhurn, 1983). D7114 was administered either chronically in the food (dose equivalent to 3 mg (kg body weight)-l day-' for 3 weeks) or acutely (5 mg kg-' I.P.) 1 hour prior to 3H20 injection. Insulin (1 IU kg-' I.P.) was injected 15 minutes before 3H20. Mitochrondrial activity was monitored by measuring the specific activity of cytochrome oxidase.Acute D7114 significantly increased basal BAT lipogenesis rates from 63.7 ± 0.6 to 109.9 ± 16.9 jug atoms H incorporated h-' (g fat-free tissue weight)-l (means ± S.E.M., n = 10-13; P < 0.03, t test). Chronic treatment with D7114 also increased BAT lipogenesis by 61 % above controls. In contrast, insulinstimulated BAT lipogenesis was lower following acute D7114: 60.0 ± 7.0 compared with 119.9 ± 20.2 (n = 9-14) in controls. Basal and insulin-stimulated lipogenesis in white adipose tissue (epididymal fat pads) was unaltered by either acute or chronic D7114. Chronic D7114 treatment significantly increased cytochrome c oxidase activity (P < 0.01, t test): 22.5 ± 2.3 compared with 13.1 ± 1.3,umol cyto c min-' in controls. Acute D7114 had no effect on cytochrome c oxidase activity.These results demonstrate that D7114 is effective in increasing basal rates of BAT lipogenesis in obese diabetic mice and that chronic dosing increases mitochondrial activity, thus increasing energy expenditure.We are grateful to ICI Pharmaceuticals for supplies of D7114.

show abstract

Section: Referencessupporting

confidence: 69%

Section: Referencesmentioning

confidence: 99%

Proceedings of the Physiological Society, 14‐15 February 1992, Bristol Meeting: Communications

1992

The Journal of Physiology

View full text Add to dashboard Cite

show abstract

“…Processes of this kind were not reported in spite of previous extensive videomicroscopy studies carried out by us and others in both PC12 Reber and Reuter, 1991) and neurons (Lipscombe et al, 1988;Silver et al, 1990). Only during the preparation of this article, preliminary results have appeared suggesting in neurons (of earth worm and Xenopus) the occurrence of waves which however, in contrast to those herewith described, largely depend on the influx of extracellular Ca 2+ (Gu et al, 1994;Ogawa et al, 1994).…”

Section: Discussionmentioning

confidence: 62%

Ca2+ waves in PC12 neurites: a bidirectional, receptor-oriented form of Ca2+ signaling.

Lorenzon

Zacchetti

Codazzi

et al. 1995

The Journal of Cell Biology

View full text Add to dashboard Cite

Abstract. Spatial and temporal aspects of Ca 2+ signaling were investigated in PC12 cells differentiated with nerve growth factor, the well known nerve cell model. Activation of receptors coupled to polyphosphoinositide hydrolysis gave rise in a high proportion of the cells to Ca :+ waves propagating non decrementally and at constant speed (2-4 #m/s at 18°C and ,,d0-fold faster at 37°C) along the neurites. These waves relied entirely on the release of Ca 2÷ from intracellular stores since they could be generated even when the cells were incubated in Ca2+-free medium. In contrast, when the cells were depolarized with high K + in Ca 2÷-containing medium, increases of cytosolic Ca 2÷ occurred in the neurites but failed to evolve into waves. Depending on the receptor agonist employed (bradykinin and carbachol versus ATP) the orientation of the waves could be opposite, from the neurite tip to the cell body or vice versa, suggesting different and specific distribution of the responsible surface receptors. Cytosolic Ca ~÷ imaging results, together with studies of inositol 1,4,5-trisphosphate generation in intact cells and inositol 1,4,5-trisphosphate-induced Ca :÷ release from microsomes, revealed the sustaining process of the waves to be discharge of Ca 2÷ from the inositol 1,4,5-trisphosphate-(and not the ryanodine-) sensitive stores distributed along the neurites. The activation of the cognate receptor appears to result from the coordinate action of the second messenger and Ca 2÷. Because of their properties and orientation, the waves could participate in the control of not only conventional cell activities, but also excitability and differential processing of inputs, and thus of electrochemical computation in nerve cells. VIDEO microscopy studies carried out on individual cells during the last several years have revealed that the changes of cytosolic Ca 2÷ concentration ([Ca2÷]~) in response to various stimuli do not develop always as a whole but can exhibit peculiar spatiotemporal aspects. In some cases, in fact, these responses have been shown to promote steep Ca 2÷ gradients between a discrete cytosolic area and the rest of the cell (Miiller and Connor, 1991;Guthrie et al., 1991;Silver et al., 1990); in others, to be composed by series of rhythmic [Ca2÷]i spikes, the oscillations (Berridge and Galione, 1988;Jacob, 1990b;Tsien and Tsien, 1990;Meyer and Stryer, 1991;Berridge, 1993), that are now believed to originate from an intracellular pacemaker or "trigger zone" (Rooney et al., 1990; D~ndrea et al., 1993;Kasai et al., 1993); in others, to consist of Ca 2÷ waves (Meyer, 1991;Amundson and Clapham, 1993;Berridge, 1993). Because of these processes, the host of functions that rely on [Ca2÷]~ for their regulation are believed to be affected to different extents or at different times depending on their localization within the stimulated cells. The present report concerns Ca 2÷ waves, i.e., intracellular events defined by their nondecremental propagation and distinct orientation, previously described in a number of ce...

show abstract

“…The role of the tip-localized Ca 2ϩ gradient in the regulation of tip growth appears to be universal (Silver et al, 1990;Schiefelbein et al, 1992;Garrill et al, 1993;Schumaker, 1996;Bibikova et al, 1997;Kuhn et al, 1998). Furthermore, the function of Rho GTPases in the control of polarized cell growth is conserved (Luo et al, 1994;Drubin and Nelson, 1996).…”

Section: The Rop1at-dependent Pathway Directly Regulates Tip-localizementioning

confidence: 99%

Control of Pollen Tube Tip Growth by a Rop GTPase–Dependent Pathway That Leads to Tip-Localized Calcium Influx

Li¹,

Lin²,

Heath³

et al. 1999

Plant Cell

351

478

View full text Add to dashboard Cite

We have shown that Rop1At, a pollen-specific Rop GTPase that is a member of the Rho family of small GTP binding proteins, acts as a key molecular switch controlling tip growth in Arabidopsis pollen tubes. Pollen-specific expression of constitutively active rop1at mutants induced isotropic growth of pollen tubes. Overexpression of wild-type Arabidopsis Rop1At led to ectopic accumulation of Rop1At in the plasma membrane at the tip and caused depolarization of pollen tube growth, which was less severe than that induced by the constitutively active rop1at. These results indicate that both Rop1At signaling and polar localization are critical for controlling the site of tip growth. Dominant negative rop1at mutants or antisense rop1at RNA inhibited tube growth at 0.5 mM extracellular Ca 2 ϩ , but growth inhibition was reversed by higher extracellular Ca 2 ϩ . Injection of anti-Rop antibodies disrupted the tip-focused intracellular Ca 2 ϩ gradient known to be crucial for tip growth. These studies provide strong evidence for a Rop GTPase-dependent tip growth pathway that couples the control of growth sites with the rate of tip growth through the regulation of tip-localized extracellular Ca 2 ϩ influxes and formation of the tip-high intracellular Ca 2 ϩ gradient in pollen tubes.

show abstract

Calcium hotspots caused by L-channel clustering promote morphological changes in neuronal growth cones

Cited by 167 publications

References 25 publications

Proceedings of the Physiological Society, 14‐15 February 1992, Bristol Meeting: Communications

Proceedings of the Physiological Society, 14‐15 February 1992, Bristol Meeting: Communications

Ca2+ waves in PC12 neurites: a bidirectional, receptor-oriented form of Ca2+ signaling.

Control of Pollen Tube Tip Growth by a Rop GTPase–Dependent Pathway That Leads to Tip-Localized Calcium Influx

Contact Info

Product

Resources

About