Eclosion Hormone-Mediated Signal Transduction in the Silkworm Abdominal Ganglia: Involvement of a Cascade from Inositol(1,4,5)trisphosphate to Cyclic GMP

This review is concerned with the roles of cyclic GMP and Ca2+ ions in signal transduction for chemotaxis of Dictyostelium. These molecules are involved in signalling between the cell surface cyclic AMP receptors and cytoskeletal myosin II involved in chemotactic cell movement. Evidence is presented for uptake and/or eflux of Ca2+ being regulated by cyclic GMP. The link between Ca2+, cyclic GMP and chemotactic cell movement has been explored using “streamer F” mutants whose primary defect is in the structural gene for the cyclic GMP-specific phosphodiesterase. This mutation causes the mutants to produce an abnormally prolonged peak of cyclic GMP accumulation in response to stimulation with the chemoattractant cyclic AMP. The production and relay of cyclic AMP signals is normal in these mutants, but certain events associated with movement are (like the cyclic GMP response) abnormally prolonged in the mutants. These events include Ca2+ uptake, myosin II association with the cytoskeleton and regulation of both myosin heavy and light chain phosphorylation. These changes can be correlated with changes in the shape of the amoebae after chemotactic stimulation. Other mutants in which the accumulation of cyclic GMP in response to cyclic AMP stimulation was absent produced no myosin II responses.A model is described in which cyclic GMP (directly or indirectly via Ca2+) regulates accumulation of myosin II on the cytoskeleton by regulating phosphorylation of the myosin heavy and light chain kinases.

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Plasma membrane inositol 1,4,5-Trisphosphate-Activated channels mediate signal transduction in lobster olfactory receptor neurons

Neuron ◽

10.1016/0896-6273(92)90243-7 ◽

1992 ◽

Vol 9 (5) ◽

pp. 907-918 ◽

Cited By ~ 156

Author(s):

D.A. Fadool ◽

B.W. Ache

Keyword(s):

Signal Transduction ◽

Plasma Membrane ◽

Olfactory Receptor ◽

Olfactory Receptor Neurons ◽

Inositol 1,4,5 Trisphosphate ◽

Receptor Neurons

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Evidence for the involvement of cyclic AMP in the pheromonal modulation of barnacle settlement

Journal of Experimental Biology ◽

10.1242/jeb.198.3.655 ◽

1995 ◽

Vol 198 (3) ◽

pp. 655-664 ◽

Cited By ~ 4

Author(s):

A Clare ◽

R Thomas ◽

D Rittschof

Keyword(s):

Signal Transduction ◽

Cyclic Amp ◽

Adenylate Cyclase ◽

Cyclic Gmp ◽

Phosphodiesterase Inhibitor ◽

Balanus Amphitrite ◽

Dibutyryl Cyclic Amp ◽

Physico Chemical ◽

Miconazole Nitrate

The involvement of cyclic AMP in the settlement of the cypris larva of Balanus amphitrite amphitrite Darwin has been examined through the use of compounds that affect intracellular cyclic AMP levels. The activation of adenylate cyclase with forskolin, and the inhibition of phosphodiesterase with 3-isobutyl-1-methylxanthine, caffeine and theophylline, significantly increased the settlement of cyprids. Although the analogue dibutyryl cyclic AMP appeared to increase settlement, the effect was not significant. No marked increase in settlement resulted from the incubation of cyprids with dibutyryl cyclic GMP, 8-(4-chlorophenylthio) (CPT) cyclic AMP or papaverine (a phosphodiesterase inhibitor). Miconazole nitrate, an adenylate cyclase inhibitor, prevented settlement, but this effect appeared to be physico-chemical rather than pharmacological. Radioimmunoassay did not clearly show whether cyclic AMP levels changed following exposure of cyprids to a pulse of crude barnacle extract. However, exposure to forskolin significantly increased the cyclic AMP titre of cyprids. We conclude that compounds that alter intracellular cyclic AMP levels alter normal patterns of cyprid settlement. Whether this is because of an alteration in signal transduction is unclear.

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