Direct measurement of local raised subplasmalemmal calcium concentrations in growth cones advancing on an N-cadherin substrate.
We have used the membrane-localized calcium probe fura-piperazine-C12H25 (FFP-18) to examine cytosolic calcium concentrations in a volume close to the plasmalemma. Although promotion of axon outgrowth by cell adhesion molecules requires extracellular calcium and is correlated with an opening of plasmalemmal channels, conventional indicators cannot detect a change in the calcium concentration in such stimulated growth cones. We have examined calcium signalling in chick retinal ganglion cell growth cones extending along stripes of N-cadherin. Subplasmalemmal calcium concentrations, reported by FFP-18, were significantly higher in these growth cones than in neighbouring growth cones on either fibronectin or polylysine. In contrast, the bulk cytosolic calcium concentration throughout the growth cone, as measured by Fura-2, was identical in growth cones on and off the N-cadherin stripes. Our results suggest that guidance cues can use extremely local calcium signals to control pathfinding decisions.
Chadborn
Neil
N
Department of Physiology, University College London, Gower Street, London WC1E 6BT, UK.
Eickholt
Britta
B
Doherty
Patrick
P
Bolsover
Stephen
S
D000818:Animals; D015820:Cadherins / Q000378:metabolism* / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002642:Chick Embryo; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives* / Q000494:pharmacology; D020439:Growth Cones / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D007202:Indicators and Reagents / Q000494:pharmacology; D011107:Polylysine / Q000378:metabolism / Q000494:pharmacology; D012160:Retina / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D015820:Cadherins; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D005353:Fibronectins; D005456:Fluorescent Dyes; D007202:Indicators and Reagents; C098105:fura-FFP18; D011107:Polylysine; D002118:Calcium; D016257:Fura-2